Advances in High Field Magnetic Resonance Imaging · General Information Conference Venue Auditorium Hypo Group Alpe Adria Bank Via Alpe Adria, 2 33010 Tavagnacco, Udine Italy Participants’

IV European Conference ofMedical Physics on

Advances in High FieldMagnetic Resonance Imaging

Associazione Italianadi Fisica Medica

Aifm

Udine, ItalySeptember 23–25, 2010

ATTI_INTERNO_Layout 1 17/09/10 13:29 Pagina 1



Advances in High Field Magnetic Resonance Imaging

CONFERENCE AND REFRESCHCOURSE

PROGRAMME



Organization’s by

EFOMPEuropean Federation of Organisation for Medical Physics

AOUUDUdine University Hospital “S. Maria della Misericordia”

AIFMItalian Association of Medical Physics

ESMRMBEuropean Society of Magnetic Resonance in Medicine and Biology

With the sponsorship

Faculty of Medicine of Udine UniversitySIRM, Magnetic Resonance Section

SISSA - International School for Advanced StudiesICTP - International Centre for Theoretical Physics

AIFM Medical Physics School “P. Caldirola”

Udine, Italy23–25 September 2010

Advances in High FieldMR Imaging

5Advances in High Field Magnetic Resonance Imaging


General Information

Conference Venue

Auditorium Hypo Group Alpe Adria Bank

Via Alpe Adria, 2

33010 Tavagnacco, Udine

Italy

Participants’ registration

Participants’ registration includes:

■ Entry to all scientific conference sessions and access to exhibition area

■ Book of Abstracts

■ Programme, name badge, conference bag and notepad

■ Coffee breaks and light lunches

Continuing Professional Development (CPM) and ECM

Conference is accreditated according to Italian (ECM credits) and EFOMP policies.

Refresh Course: EFOMP: 19 CPD credit-points. ECM: requested for Medical Physicists.

Conference: EFOMP: 16 CPD credit-points; ECM: requested for Medical Physicists; 10

credits for Radiologists.

Proceedings

Scientific Committee will ask authors of selected presentations to submit a paper to the

European Journal of Medical Physics - Physica Medica.



6 Advances in High Field Magnetic Resonance Imaging


Scientific Programme Committee

Massimo Bazzocchi, Udine, IT (Udine University)Stelios Christofides, Nicosia, CY (EFOMP)

Maria Assunta Cova, Trieste, IT (SIRM)Paolo Ferrari, Trento, IT (AIFM)

Gisela Hagberg, Roma, IT (AIFM)Renata Longo, Trieste, IT (ICTP, Trieste University)

Renato Padovani, Udine, IT (AOUUD)Alfonso Ragozzino, Napoli, IT (SIRM)Raffaella Rumiati, Trieste, IT (SISSA)

Klaus Scheffler, Basel, CH (ESMRMB)Fritz Schick, Tuebingen, DE (ESMRMB)Oliver Speck, Frieburg, DE (ESMRMB)

Alberto Torresin, Milan, IT (EFOMP)Michela Tosetti, Pisa, IT (AIFM)

Organising Committee

Marco BandFaustino Bonutti

Margherita CrespiClaudio Foti

Marta MaieronMaria Rosa Malisan

Eugenia MorettiAnnalisa Trianni

Conference Chairman

Renato PadovaniMedical Physics Dpt., University Hospital, Udine, Italy

E-mail: [email protected]





Technical Exhibition

Conference Secretariat

MD STUDIO CONGRESSI SNCVia Roma, 8, 33100 – Udine (Italy)

Tel.: +39 0432 227673 – Fax: +39 0432 507533E-mail to: [email protected]

Conference Website

All documents and information about the conference are available athttp://www.udine2010.fisicamedica.org





Programme Overview

Wednesday 22 Thursday 23 Friday 24 Saturday 25

8.00 – 11.00Refresh Course



11.00OPENING CEREMONY

9.00 – 10.30SESSION III

Recent Advancement inMR Applications

9.00 – 10.30SESSION VI

Safety Issue andRegulation

10.30 – 11.00Session VI cont.

10.30 – 11.00Coffee Break

11.00 – 11.30 Coffee Break

11.30 – 13.00SESSION I

Methods and Technology

11.00 – 12.30Session III cont.

11.30 – 12.30SESSION VIIRound table

Education and Training

13.00CLOSING CEREMONY

13.00 – 14.00 Lunch 12.30 – 13.45 Lunch


14.00 – 16.30SESSION II

Methods and Technology

13.45 – 15.15SESSION IV

Neuroimaging





17.00 – 17.45Session II cont.

15.40 – 16.30SESSION V

Quality Assurance

16.30 – 17.30Session V cont.






Wednesday 22

Refresh Course organized by AIFM Medical Physics School “Caldirola” and ESMRMB

ADVANCED TECHNIQUES IN MAGNETIC RESONANCE

14.00OpeningAlberto Torresin (AIFM), Oliver Speck (ESMRMB)

Chair: Alberto Torresin

14.00 Contrast mechanisms (T1 T2 T2*) Mara Cercignani (IT)

15.00 Basic hardware: magnet, gradients and RF coils Gisela Hagberg (IT)

16.00 Coffee Break

16.30Image formation in MR imaging: from k-spaceto parallel imaging

Jacques Bittoun (FR)

17.30 Discussion

Thursday 23

Introduction to scientific sessionChair: Gisela Hagberg

8.00Radio frequency coils: basic principles andadvanced applications

Marcello Alecci (IT)

9.00 Origins of image distortion and artifacts Jesper Andersson (UK)

10.00Changes in MR physics when moving to higher field strengths: drivers for methodsand technology development

Fritz Schick (DE)

Conference Programme





IV EUROPEAN CONFERENCE OF MEDICAL PHYSICS

ADVANCES IN HIGH FIELD MAGNETIC RESONANCE IMAGING

11.00 Opening Ceremony

SESSION I - Development of methods and technology for high-field MRI

Chair: Stelios Christofides, Oliver Speck

11.30 Traveling wave MR Rolf Pohmann (DE)

12.00 Novel motion correction techniques Maxime Zaitsev (DE)

12.30Novel pulse sequence approaches addressing high-field limits

Oliver Speck (DE)

13.00 Lunch

SESSION II - Development of methods and technology for high-field MRI

Chair: Fritz Schick, Michela Tosetti

14.00Design of High Field Magnets and MR Scanners for Biomedical Use

Gregory Hurst (US)

14.30Clinical MultiTransmit MRI - The Why and The How

Paul Harvey (NL)

15.00Parallel transmission: current and futureapplications of multi-dimensional RF pulses

Ulrich Katscher (DE)

15.30 7T Italian project Michela Tosetti (IT)

16.00 Ultra High field MRI of the future Franz Schmitt (DE)

16.30 Coffee Break

Chair: Renata Longo

17.00Transmit/Receive RF coil pair designed for MRIexperiments on small animals at 2T

Daniel Papoti (BR)





17.15Dynamic localised 31P MRS of exercising human muscle at 7T

Ewald Moser (AT)

17.30Optimization of BCG artifact removal for single-trial EEG-fMRI recordings at 4T

Sara Assecondi (IT)

17.45Diffusion-Weighted Imaging of the breast at 3T. State-of-art and personal experience

Michele Lorenzon (IT)

18.00High-resolution resting-state network analysis at 7T

Ewald Moser (AT)

Friday 24



Introduction to scientific sessionChair: Michela Tosetti

8.00 High Field MR applications: what can we expect? Oliver Speck (DE)

8.45 Discussion

IV EUROPEAN CONFERENCE OF MEDICAL PHYSICS

SESSION III – Recent advancements in MR applications

Chair: Massimo Bazzocchi, Maria A. Cova

9.00 Novel contrast media Silvio Aime (IT)

9.30Cerebral lesions in functional eloquent brain location

Miran Skrap (IT)

10.00 Improved imaging of joints at higher fields Siegfried Trattnig (AT)

10.30 Coffee Break

11.00

Diffusion-weighted magnetic resonance imaging (DW-MRI) at 3T in evaluating water diffusion pattern in cirrhotic and healthy livers: preliminary results

Daniele Bagatto (IT)





11.15Is SWI brain vessel change suitable for enhance functional activation cortical maps?

Marta Maieron (IT)

11.30DT-MR images: a CAD System for CerebralGlioma and Therapy Follow-up

Giorgio De Nunzio (IT)

11.45 Cognitive impairment in MS: a TBSS study Chiara Mastropasqua (IT)

12.00Breath-hold induced BOLD MRI signalchanges in the spinal cord

Marta Maieron (IT)

12.15 Probabilistic fibre tracking: a possible validation? Alessio Moscato (IT)

12.30 Lunch

SESSION IV – Neuroimaging

Chair: Miran Skrap, Paolo Ferrari

13.45 Neuroimaging: anatomy Giampaolo Basso (IT)

14.10Cortical structure observed by phase contrast at high fields

Rolf Pohmann (DE)

14.35Anatomical and spatial components inimitation of intransitive actions

Raffaella Rumiati (IT)

15.00

Combining behavioral, rTMS and fMRI datain the understanding of the role of righttemporal parietal junction during emotionalegocentricity bias

Giorgia Silani (CH)

15.15 Coffee Break

SESSION V – Quality Assurance

Chair: Alberto Torresin, Fabrizio Levrero

15.40Geometric accuracy, functional sensitivity and specificity: optimization experiences for human functional neuroimaging at 4T

Jorge Jovicich (IT)





16.05 Quality of fMRI studies Paolo Ferrari (IT)

Chair: Gisela Hagberg

16.30Biophysical principles and acceptance test inMRgFUS

Alberto Torresin (IT)

16.45The integration of MRI in the radiation treatment planning of localized prostate cancer

Eugenia Moretti (IT)

17.00Are the commercial tools embedded on MR-scanners suitable for fMRI analysis?

Marta Maieron (IT)

17.15Preliminary experience for evaluation of scanner performance and stability for MRI studies at 3T

Marco Band (IT)



Guided exerciseChair: Oliver Speck, Michela Tosetti

17.30Susceptibility-weighted imaging and data processing

Richard Bowtell (UK)

18.30 Discussion

Saturday 25



Introduction to scientific sessionChair: Renata Longo

8.00 Safety at high field – where do we stand? Steve Keevil (UK)

8.45 Discussion





SESSION VI – Safety Issues and Regulation

Chair: Penelope Allisy-Roberts, Paolo Vecchia

9.00Protection of patients in MRI: the position ofICNIRP

Paolo Vecchia (IT)

9.30Regulation of occupational EMF exposure in MRI - where are we?

Steve Keevil (UK)

10.00The medical physics expert for non-Ionizingradiation applications in the healthcareenvironment

Penelope Allisy-Roberts (FR)

10.30 Safety in high field MRI: practical aspects Renzo Delia (IT)

10.45Accuracy and typical values of specific Absorption Rate (SAR) during routine MR scanning

Wilhelm Van der Putten (IE)

11.00 Coffee Break

SESSION VII – Round table on education and training

Moderators: Oliver Speck (ESMRMB), Stelios Christofides (EFOMP)

11.30

EFOMP-ESR Medical Physics education guidelinesWilhelm Van der Putten (IE)

Education and training of Medical PhysicistsIOMP recommendations

Fridjof Nuesslin (DE)

MRI physics education for diagnosticradiographers - an initial study

Carmel Caruana (MT)

EMIT project for e-training in medical imaging(MRI module)

Slavik Tabakov (UK)

Activities of national working groups on MRof European Medical Physics Societies

The Institute of Fisics and Engeneering in Medicine.Magnetic Resonance Special Interest Group

AIFM Work Group in advanced topics inMagnetic Resonance

Steve Keevil (UK)

Fabrizio Levrero (IT)

13.00 Closing Ceremony








CONFERENCE ABSTRACTS



SESSION I – Development of methods and technology for high-field MRI

Traveling wave MRR. PohmannMax-Planck Institute for Biological Cybernetics in Tübingen, Germany

Ultra-high field MR often suffers from the inhomogeneous distribution of the exciting rf-field, as well as from the increasing complexity of rf-coils used to overcome this problem.The Traveling Wave approach represents a new way of applying the necessary rf-fieldneeded for MR excitation by using the magnet bore as a waveguide. A simple patchantenna that can be placed at the end of the bore is used to generate the rf-field, whichpropagates through the magnet.Here, the principles of the traveling wave approach are discussed. After a shortintroduction of the physical background, properties and current applications of thetechnique are shown. Novel ways of improving the field homogeneity and of guiding thefield to where it is needed are presented.

Novel motion correction techniquesM. ZaitsevUniversity Hospital Freiburg, Freiburg, Germany

Motion during MR image encoding produces inconsistencies in the acquired k-space data,which results in well-known motion artifacts. In clinical settings patient motion during MRIexaminations renders a significant fraction of scans non-diagnostic. Additionally, manypatients e.g. elderly people, Parkinson patients, young children, who may have benefitedfrom an MRI-based diagnosis, are merely treated as unacceptable for MRI for their inabilityto maintain positions of their body parts over prolonged periods of time. Recently, due tothe increased availability of ultra-high filed imagers of 7T and above capable of sub-millimeter resolution in vivo, it became apparent that even in normal subjects involuntarilymotion of about a millimeter may limit significantly the achievable image quality.The possibility to correct for a significant part of motion-induced image artifacts as wellas the importance of such corrections for structural and functional imaging has beenrealized by many researchers, e.g.[1-3]. The majority of MRI methods attempting toaddress motion artifacts can be categorized based on (i) the ways to detect motion or itseffects and (ii) the ways to apply corrections or suppress the undesired artifacts. In terms of motion detection the most popular approaches are either based on so-calledMR navigator signals[4,5] or the analysis of the acquired imaging data themselves. Thelater analysis may be performed either directly on the raw k-space data[6] or following theimage reconstruction[3,7]. An alternative option of gathering motion information of theimaged sample using additional position tracking hardware receives an increasedattention over the recent years[2,8-10].







The most common artifact suppression strategies include: (a) conceptual approaches,where encoding schemes are optimized to reduce their motion sensitivity[11,12]; (b) post-processing approaches, where the detected motion is compensated for using signalmodels or data redundancy, which includes an option of rejecting damagedunrecoverable scans[6,13]; (c) adaptive or so-called prospective correction approaches,where the parameters of the imaging method are altered based on the detected subjectmotion[2,8-10]. Ultimately the three mentioned correction options may be combined toachieve the best motion artifact suppression.The above classification allows one to approach the motion correction problem in astructured manner and optimize separately the individual steps of the correction pipeline.Additionally, established technologies like animation motion capture may be adopted toprovide real-time position information. The only obstacle at this juncture is unfortunatelygiven by the presence of the MR scanner itself, requiring selection or development of anappropriate position tracking technology, capable of coping with the presence of thestrong magnetic field and tight spatial constrains of the MRI environment, while providinga sufficient accuracy of tracking data with a low latency. Prospective motion correction approaches offer a number of advantages, where the mostsignificant ones are the reduction of spin history effects and increased k-space dataconsistency. However, random or systematic errors in the motion tracking informationitself may negatively affect the image quality even in absence of true subject motion.Possible image deterioration due to tracking data noise and the overall robustness of themethods are the main issues with prospective correction.Assuming the noise statistics of tracking data is known, it is possible to analyze thestrength of the resulting artifacts and thus formulate the requirements to the accuracy ofmotion information. For the case of line-by-line correction in k-space, Gaussian whitenoise in the position component of the tracking data transforms into incoherent ghostingartifacts distributed along the phase encoding direction[14]. The mean power of theseartifacts is proportional to the variance of the position and an averaged imagecharacteristic termed mean edge power. The abovementioned incoherent ghosting artifacts are effectively masked by the imagenoise and are unnoticeable when the mean artifact power lies well under the variance ofthe image noise. For a given application a typical mean image edge power can beestimated based on some existing high quality images. Provided the typical SNR valuesand typical images it is possible to formulate the requirements to the position noise. Thus,for the majority of high-resolution brain imaging protocols the standard deviation of theposition data shall be by a factor 5 to 10 lower than the desired voxel size[14]. Motion correction approaches based either on MR navigators or on external trackingdata have a number of important differences. External motion tracking systems calculatesample position in a separate coordinate frame, e.g. relative to the tracking camera. Thus,for a proper interpretation, the coordinate transformation from the tracking frame to theMR frame needs to be defined with a high precision. Procedure of finding such atransformation is termed cross-calibration and is typically too time consuming to be

Advances in High Field Magnetic Resonance Imaging20




performed for each subject[2]. On the other hand, position information delivered by thenavigators is naturally in the MR coordinates and not only fulfills perfectly the cross-calibration conditions, but also shares imperfections and non-linearities with the imagingmethods. Regarding the temporal axis, MR navigators are intrinsically required to be interleavedwith the actual imaging acquisitions, which requires substantial sequence modifications,reduces scanning efficiency, limits temporal resolution of the motion sampling andintroduces an inevitable delay between the position data and the possible points ofcorrections. Moreover, navigators apply additional RF and gradient pulses, possiblyaffecting signal steady states and eddy currents. Quite contrary, external tracking hasan advantage of operating simultaneously with the MR imager. State of the art opticalmotion tracking devices are characterized by high frame rates of about 10 to 100 framesper second with low signal processing and transport latencies. An appealing in some situation options are given by tracking systems specifically relyingon some of the MR imager’s features, e.g. B0 field or switched gradients[8,15,16]. Thesetracking approaches share some of the advantages and disadvantages of both MRnavigators and external tracking systems relying on non-MR physical principles.Most of the external motion tracking methods and also some of the MR navigatorstrategies are not capable of measuring the position of the imaged organ or objectdirectly. Instead, positions of some other objects, special markers or parts of the trackingsystem are defined. In case of a rigid body motion model, the goal of the prospectivecorrection is to ensure that the marker position relative to the encoding coordinates withinthe image volume remains constant over the duration of the MR experiment. Non-rigidmotion models rely on a possibility of defining a deterministic transformation betweenthe motion of the markers or a set of navigators and the optimal position of the imagedvolume.Regardless of the chosen motion tracking approach, determining the relation betweenthe tracking data and the optimal positioning of the imaging volume, as well as insuringthat this relation remains valid over the course of the MRI acquisition, is of the paramountimportance. In case when markers or other positioning devices are used this requires adevelopment of a robust marker attachment strategy. Mouthpieces, headbands, gogglesand glasses have been tested with varying degrees of positioning accuracy and subjectcomfort. Several external tracking devices have been shown to work well in MRI environment. Avariety of optical tracking devices has been tested, including laser, stereoscopic andmonovision systems with 2D structured markers. Single-camera tracking approach basedon a retro-grate reflector (RGR) targets deserve a special mention[17]. As a single camerais used for tracking, only one optical pathway needs to be ensured. The tracking targetsin turn can be miniaturized to about 1-2cm size, while preserving a sub-millimeterpositional accuracy.Independent of the chose of the external tracking source, implementation of theprospective correction requires a certain effort from the sequence programmers and is

Advances in High Field Magnetic Resonance Imaging 21



typically vendor-specific. At the University Hospital Freiburg we have implemented asoftware solution for the Numaris 4 platform (Siemens Healthcare, Erlangen, Germany),which only requires the external tracking device to be physically connected to thescanner’s internal network. Prospective position correction is handled by a separatelibrary, responsible for communication with the tracking device and coordinatetransformations. Although the major work is done by the library, some minor sequencemodifications are still required to make prospective corrections possible for the givensequence. The library logs all the tracking data and decisions and communicates withthe image reconstruction system, which enables post-processing or combined correctionoptions. Gradient-recalled echo, spin echo[2], BOLD EPI[18], spectroscopic PRESS[19] andmany more sequences have been implemented successfully. Despite of the major advances in the field of real-time motion correction significantchallenges remain. Handling of localized receiver coil sensitivities, changes in B0 andB1+, gradient non-linearities and non-rigid motion are some of the yet unsolved problems.Specifically to the use of external tracking devices, improved cross-calibration, drift andtemporal latency calibration routines would be of a great help. Furthermore, issues withsubject preparation and handling, and especially attachment of the tracking devices,need to be resolved in future. Generally speaking, limited robustness and handlingdifficulties remain the main obstacles preventing the technology from a wider acceptancein the clinical and research fields.

References: 1. Nehrke, K. and P. Börnert, Prospective correction of affine motion for arbitrary MR

sequences on a clinical scanner. Magn Reson Med, 2005. 54(5):1130-8.2. Zaitsev, M., C. Dold, G. Sakas, J. Hennig, and O. Speck, Magnetic resonance imaging of

freely moving objects: prospective real-time motion correction using an external opticalmotion tracking system. Neuroimage, 2006. 31(3):1038-50.

3. Friston, K.J., J. Ashburner, J.B. Poline, C.D. Frith, R.S.J. Frackowiak, Spatial realignmentand normalization of images. Hum Brain Mapp 1995;2:165-89.

4. Fu, Z.W., Y. Wang, R.C. Grimm, P.J. Rossman, J.P. Felmlee, S.J. Riederer, and R.L. Ehman,Orbital navigator echoes for motion measurements in magnetic resonance imaging. MagnReson Med, 1995. 34(5):746-53.

5. Welch, E.B., A. Manduca, R.C. Grimm, H.A. Ward, and C.R. Jack, Jr., Spherical navigator echoesfor full 3D rigid body motion measurement in MRI. Magn Reson Med, 2002. 47(1): 32 41.

6. Larkman, D.J., D. Atkinson, J.V. Hajnal, Artifact reduction using parallel imaging methods.Top Magn Reson Imaging. 2004 Aug;15(4):267-75.

7. Kim, B., J.L. Boes, P.H. Bland, T.L. Chenevert, C.R. Meyer, Motion correction in fMRI viaregistration of individual slices into an anatomical volume. Magn Reson Med1999;41(5):964-72.

8. Krueger, S., T. Schaeffter, S. Weiss, K. Nehrke, T. Rozijn, and P. Boernert. Prospective Intra-Image Compensation for Non-Periodic Rigid Body Motion Using Active Markers. ISMRM2006, Seattle; 3196.




9. Qin, L., P.v. Gelderen, F. Jin, Y. Tao, and J.H. Duyn. Prospective head movement correctionfor high resolution MRI using an in-bore optical tracking system. ISMRM 2007, Berlin; 1828.

10. Aksoy, M., R. Newbould, M. Straka, S. Holdsworth, S. Skare, J. Santos, and R. Bammer. Areal time optical motion correction system using a single camera and 2D marker. ISMRM2008, Toronto; 3120.

11. Yuan, C., G.T. Gullberg, D.L. Parker, Flow-induced phase effects and compensationtechnique for slice-selective pulses. Magn Reson Med. 1989 Feb;9(2):161-76.

12. Jhooti, P., F. Wiesmann, A.M. Taylor, P.D. Gatehouse, G.Z. Yang, J. Keegan, D.J. Pennell,D.N. Firmin, Hybrid ordered phase encoding (HOPE): an improved approach for respiratoryartifact reduction. J Magn Reson Imaging. 1998 Jul-Aug;8(4):968-80.

13. Bammer, R., M. Aksoy, C. Liu. Augmented generalized SENSE reconstruction to correct forrigid body motion. Magn Reson Med 2007;57(1):90-102.

14. Maclaren, J., O. Speck, D. Stucht, P. Schulze, J. Hennig, M. Zaitsev. Navigator accuracyrequirements for prospective motion correction. Magn Reson Med. 2010 Jan;63(1):162-70.

15. Ooi, MB, S. Krueger, W.J. Thomas, S.V. Swaminathan, T.R. Brown. Prospective real-timecorrection for arbitrary head motion using active markers. Magn Reson Med. 2009Oct;62(4):943-54.

16. Elgort, DR, W.Y. Wong, C.M. Hillenbrand, F.K. Wacker, J.S. Lewin, J.L. Duerk. Real-timecatheter tracking and adaptive imaging. J Magn Reson Imaging 2003;18:621-6.

17. Armstrong, B., B. Andrews-Shigaki, R.T. Barrows, T.P. Kusik, T. Ernst, O. Speck Performanceof Stereo Vision and Retro-Grate Reflector Motion Tracking Systems in the SpaceConstraints of an MR Scanner. ISMRM 2009; #4641.

18. Speck, O., J. Hennig, M. Zaitsev. Prospective real-time slice-by-slice motion correction forfMRI in freely moving subjects. Magma 2006;19(2):55-61.

19. Zaitsev, M., O. Speck, J. Hennig, M. Büchert. Single-Voxel MRS with Prospective MotionCorrection and Retrospective Frequency Correction. NMR in Biomed 2010.

AcknowledgementsThis work is in part supported by the INUMAC project granted by the German FederalMinistry of Education and Research (01EQ0605); and in part by the National Institute ofHealth (1R01 DA021146).

Novel pulse sequence approaches addressing high-field limitsO. SpeckDept. of Biomedical Magnetic Resonance, Otto-von-Guericke University Magdeburg,Germany

The increasing interest in MRI at high magnetic field (i.e. higher than 3T) has mainlybeen driven by neuro-imaging applications. With the more widespread availability of highfield systems many other applications benefit from the improved signal to noise ratio athigher magnetic field.





However, a number of challenges have to be addressed. In tissue, the spin-latticerelaxation time T1 increases while the spin-spin relaxation time T2 is relatively constantor slightly reduced (depending on the measurement method) and T2* decreases due tothe increased local field variation. To compensate for this, obviously longer repetition andshorter echo times are required for conventional methods. Another dominant effect ofhigher field strength is the increased RF power deposition and the reduced spatialhomogeneity of the RF amplitude generated by volume transmit-coils.SAR restrictions are a main limiting factor at high field strength and have to be consideredin the sequence design. The increased frequency dispersion, which is of advantage forspectroscopic applications, also implies that off-resonance related imaging properties,e.g. the chemical shift of fat or dephasing effects in steady state sequences, increasewith field strength.In order to keep the artifact level comparable and to account for the shorter T2*, higherimaging bandwidth is needed. Correspondingly, the image noise increases proportionalto the square root of the bandwidth partially annihilating the SNR gain. On the other handthis allows acquiring more signals, e.g. more slices in the same TR. However, this simpleadaptation to higher field strength is not always possible, e.g. in situations, were thegradient strength or peripheral nerve stimulation limit the bandwidth as in EPI.In general, similar pulse sequences are used as at lower field strength.However, a number of adaptations are required. In particular, the high SAR is beingreduced by the use of longer pulses with lower (or variable) flip angles such as in theVERSE (variable rate selective excitation) and hyper-TSE methods. In general, manyresearchers prefer to use gradient echo rather than spin echo based methods at highmagnetic field. GRE methods offer high resolution, high contrast (albeit T2*) at low SARlevels in short acquisition time. Many high field applications in the brain, e.g. fMRI, pMRI,or DTI, rely on echo planar imaging. While SAR and flip angle dependence are minorissues in EPI, the increased local field variations cause markedly increased geometricimage distortions and signal loss.Geometric distortions can be as large as a few centimeters and need to be correctedbased on reference measurements. In conclusion, MR imaging at high field has been very successful over the past few yearsand many of the obstacles that were thought to be prohibitive of high field imaging havebeen overcome by technical developments of the system hardware and sequenceoptimization. However, not all clinical routine methods are available for 7T at this point intime.





SESSION II – Development of methods and technology for high-field MRI

Design of high field magnets and MR scanners fro biomedical useG. HurstGE Healthcare, United States

The evolution of NMR/MRI scanners has followed a steady path of increasing fieldstrengths. This lecture will look at the history, current status, and forward view of thesescanners, from the points of view of motivations, challenges, and technology solutions.Special attention will be given to magnet design factors and solutions, including fieldstrength, bore size, conductor materials, homogeneity, fringe field containment, and cost.

Clinical MultiTransmit MRI - The why and the howP. HarveyPhilips Healthcare, Netherlands

As MRI has moved to higher field strengths, the RF frequency for proton MRI has alsoincreased. Partly due to the electrical properties of the human body and partly due tothe physical scale, the RF excitation uniformity and contrast obtainable from a typicalconventional clinical 3.0T system is sometimes not adequate for reliable clinical diagnosisin some applications and with some patients. This complication has been a barrier torealizing the full benefits of the higher field strength across the whole range of clinicalapplications. Over the years that clinical 3.0T imagers have been available there havebeen various attempts to address the so-called dielectric shading problems with varyingdegrees of success and compromise. It has long been recognized, however, that bysuitable manipulation of RF transmit field uniformity it could be possible to fundamentallysolve the dielectric shading problems at source. This approach, up until today, has beenconsidered both complex and technically challenging. Serious research into parallel RFtransmission has been undertaken since 2003 and in 2008 Philips Healthcare introducedthe very first clinical 3.0T MRI product to utilized parallel RF transmission, referred to asMultiTransmit. This presentation briefly explains the principles of MultiTransmit, examinesthe history of the development of parallel transmission, and demonstrates how patientadaptive MultiTransmit can and does unlock the full benefits of clinical 3.0T MRI.

Parallel transmission: current and future applications of multi-dimensional RFpulsesU. KatscherPhilips Research Europe, Hamburg, Germany

Parallel RF transmission for MRI originates from two formerly developed techniques,





multi-dimensional RF pulses[1,2] and parallel imaging[3,4]. Multi-dimensional RF pulsesenable RF excitation patterns with arbitrary spatial-spectral shapes. Parallel imagingutilizes multiple RF receive coils to shorten the trajectory in the acquisition k-space, andthus, the duration of MR acquisitions. Combining these two techniques, parallel RFtransmission utilizes multiple RF transmit coils to shorten the trajectory in thetransmission k-space, and thus, the duration of multi-dimensional RF pulses[5-7]. Theresulting acceleration broadens the range of possible applications of multi-dimensionalRF pulses, particularly the compensation of signal inhomogeneities at high main fieldstrengths[8,9]. Other applications are given by, e.g., reduced FOV imaging, arterial spinlabeling, localized spectroscopy, or exploring the spectral dimension of RF pulses (see,e.g.,[10,11]).

References:1. Pauly J et al., A k-space analysis of small-tip-angle excitation, JMR 81 (1989) 43.2. Pauly J et al., A linear class of large-tip-angle selective excitation pulses, JMR 82 (1989)

571.3. Sodickson DK et al., Simultaneous acquisition of spatial harmonics (SMASH): fast imaging

with radiofrequency coil arrays, MRM 38 (1997) 591.4. Pruessmann KP et al., SENSE: sensitivity encoding for fast MRI, MRM 42 (1999) 952.5. Katscher U et al., Transmit SENSE, MRM 49 (2003) 144.6. Zhu Y, Parallel excitation with an array of transmit coils, MRM 51 (2004) 775.7. Grissom W et al., Spatial domain method for the design of RF pulses in multicoil parallel

excitation, MRM 56 (2006) 620.8. Ullmann P et al., Experimental analysis of parallel excitation using dedicated coil setups

and simultaneous RF transmission on multiple channels, MRM 54 (2005) 994.9. Zhang Z et al., Reduction of transmitter B1 inhomogeneity with transmit SENSE slice-select

pulses, MRM 57 (2007) 842.10. Setsompop K, Broadband slab selection with B1+ mitigation at 7T via parallel spectral-

spatial excitation, MRM 61 (2009) 493.11. Malik SJ et al., Subject-specific water-selective imaging using parallel transmission, MRM

63 (2010) 988.

Ultra High field MRI of the future F. Schmitt Siemens Medical Division Erlangen, GermanyThe intrinsic improvements in signal to noise ratio, spectral dispersion and susceptibilitycontrast with increasing static magnetic field strength, B0, has spurred the developmentof MR technology from its very first application to clinical imaging.With maturing magnet, RF and gradient technology, the clinical community has seen thestatic magnetic field of clinical systems increase from 0.2T to 1.5T to 3.0T. Today, the“Ultra High Field” label for human MR research describes initial experiences with 7T, 8T





and 9.4T systems. While currently primarily research instruments, this technology isbound to cross the boundary into the clinical diagnostic arena as key technical issuesare solved and the methodology proves itself for addressing clinical issues. In this talk,we discuss the particular advantages and disadvantages of ultra-high field systems forclinical imaging as well as some of the immediate technological challenges which mustbe solved to derive the full benefit of the extraordinary sensitivity of these systems whichhas been glimpsed from their research use.

Transmit/receive RF coil pair designed for MRI experiments on small animals at 2TD. Papoti E.L.G. Vidoto, M.J. Martins, A. Tannús Instituto de Física de São Carlos, Universidade de São Paulo, Brazil

AimThe aim of this work is to develop and optimize a set of actively decoupled Transmit-Only/Receive-Only RF coils specifically designed to perform MRI experiments on smallanimals. To optimize parameters such as RF field homogeneity and detuning duringreceive period, we built linearly driven RF transmitter coils with three different geometries:one 8-rung Birdcage, one 16-rung Birdcage and our proposed geometry named DoubleCrossed Saddle (DCS). To operate as receiver only coil, a 2-Channel Phased Arrayactively detuned was built, where the decoupling between each coil element wasachieved through geometrical overlapping, preventing the need of low input impedancepreamplifiers.Materials and MethodsAnticipating comparison of the RF field homogeneity, the Birdcages and the DCS Coilwere built with exactly the same dimensions, with 10 cm inner diameter and 20 cm length.All coils were tuned and matched inside a RF shield 15 cm in diameter and 23 cm inlength and are actively detuned during receiving period inserting PIN diodes through RFchoke inductors in series with Birdcage s and DCS coil tuning capacitors. Each coilelement of the 2-Channel Phased Array consists of 1.5 cm inner diameter loops with 2turns of wire conductor with 1.35 mm in diameter. The detuning during transmitter periodwas achieved using a blocking resonant circuit in parallel with tuning capacitors activatedupon conduction on PIN diode. To eliminate shield currents and to avoid coil-to-coil cablecoupling, a cable trap was inserted along RF coil cables. B1 field maps were obtainedfrom the transmitter coils using the Compensated Double Angle Method and comparedwith the calculated maps using Biot-Savart approach. SNR was measured using thesum-of-squares image combination obtained from spherical phantom with 4 cm diameter.Murine head in vivo images were obtained by using all coils as transmitter and the 2-Channel Phased Array as receiver. All experiments were performed with an Avance III –MRI electronics from Bruker Biospin operating with a 31 cm 2.0 Tesla horizontal Oxfordmagnet.Results and Discussion





The obtained B1 field maps show good agreement with Biot-Savart simulations andindicate that the 16-rung Birdcage is superior to other transmitter coils in RF fieldhomogeneity, followed by the DCS and the 8-rung Birdcage. However, the decouplingwith the 2-Channel Phased Array during reception measured in the 16-rung Birdcage isinferior if compared to the DCS coil and with 8-rung Birdcage due to the great numberof capacitors in its structure, which makes the DCS coil the best choice to operate astransmitter coil. The SNR measured as well as the in vivo images obtained confirm thatthe DCS coil is better decoupled during reception than the 8-rung and 16-rung Birdcages.ConclusionsBased on the B1 field maps obtained experimentaly and the decoupling during receptionwe conclude that the DCS coil is the best choice to operate as trasmitter coil with the 2-Channel Phased Arrays. SNR measurements and in vivo images confirm the DCS coilsuperiority among the 8-rungs and 16-rungs lienarly driven Birdcages.

Dynamic localised 31P MRS of exercising human muscle at 7TE.Moser, M. Meyerspeer, E. Unger, T. Mandl, T. Scheenen, G.J. Kemp Centre for Medical Physics and Biomedical Engineering, Medical University of Vienna,Austria

AimThe increased sensitivity of ultra high field MR is attractive for 31P magnetic resonancespectroscopy (MRS) with its intrinsically low SNR. 31P MRS can reveal information onmetabolism relevant to the understanding of physiology in healthy organs as well as formetabolic disorders, non-invasively and with temporal resolution. Dynamic studies ofmetabolism are often conducted using non-localised surface coil acquisitions. Singlevoxel MRS localisation can increase specificity by limiting the VOI e.g. to a singleexercising muscle, at the cost of SNR which may in turn necessitate temporal averaging,thus resulting in lower temporal resolution. To alleviate this limitation, a short echo singlevoxel spectroscopic method with adiabatic refocussing was applied at ultra high field, inaerobically exercising human gastrocnemius muscle. Data are compared to non-localisedspectra, acquired in exercise bouts with equal intensity.Materials and MethodsHealthy subjects (n = 5) performed plantar flexion exercise on an ergometer in the MRscanner. A dual tuned loop coil, d=10 cm (Rapid Biomedical, D) was used in a Siemens7T whole body MR system. Pulse-acquire spectra were excited with a 250 µs block pulse.Alternatively, an appropriately sized voxel (avg. 37 ml), localised with semi-LASER [1]with short echo time was placed in the gastrocnemius muscle. Spectra were acquiredevery 6s during rest, exercise and recovery.Results and DiscussionRobust quantification of PCr from a single exercising muscle was possible from singleacquisitions with a temporal resolution of 6 s (=TR) to fit PCr recovery time courses. The





muscle’s resting pH (mean ± SD) was 7.05 ± 0.03, in all experiments. End exercise pHwas 6.83 ± 0.17 and 6.85 ± 0.07 in the localised experiments. Only in non-localisedexperiments a split of the Pi peak with 0.6 ± 0.1 ppm was observed in four (of 5) subjects,resulting in ambiguous end exercise pH quantification. After a priming exercise bout, PCrdepletion was 78 ± 7% when measured with semi-LASER localisation and significantlyless pronounced (p = 0.02) without localisation 48 ±12 %. Highly significant differences(p = 0.0009) in initial PCr recovery rate d[PCr]/dt were found between localised and non-localised acquisitions. Interestingly, we observed a trend towards faster PCr recovery inthe localised spectra (where PCr depletion is greater). Thus the implied d[PCr]/dt is morethan proportionally increased, but the apparent physiological implication is that this isachieved by an increase in effective mitochondrial function in ‘harder-working’ regions.ConclusionsSingle voxel 31P MRS with semi-LASER is a single shot technique and, as such, hasrelatively high time resolution (6 s, shorter TR is possible). SNR is sufficient to quantifythe PCr time course of a single exercising muscle. Also pH quantification is feasible, withlower time resolution. In conclusion, we believe that by its increased specificity, localiseddynamic 31P MRS can offer new insights and understanding of energy metabolism inexercising muscle.

References:1. Scheenen, T. W., et al. Magn Reson Mater Phy, 2008. 21(1-2):95-101.

Optimization of BCG artifact removal for single-trial EEG-fMRI recordings at 4TS. Assecondi, A. Bianchi, P. Ferrari, V. Mazza, J. Schwarzbach, J. Jovicich CIMeC, University of Trento, Italy

AimDuring simultaneous EEG-fMRI recordings, the interaction between the strong magneticfield of the MR scanner, the recording system and the human body generates artifactsin the EEG signal. Among others, the ballistocardiographic artifact (BCGa) is related tothe blood flowing into the arteries leading to small electrode movements, and it isproportional to the strength of the externally applied static magnetic field. Severalapproaches have been proposed to reduce the BCGa. This work proposes a non-linearremoval technique for the BCGa, that optimizes data quality on single-trial recordings.The performance of the proposed method is investigated in simultaneous EEG-fMRIrecordings at 4 T. Materials and MethodsWe propose a non-linear average artifact subtraction approach (nl-AAS) based onDynamic Time Warping (DTW) (Sakoe & Chiba, 1978), a technique that performs anonlinear deformation of the time axis of two time series in order to minimize a predefineddistance measure. An artifact template is calculated by averaging several BCGa





occurrences, after non-linear alignment by means of DTW. The nonlinear alignmentallows us to average BCGa occurrences of variable length, according to the RR intervals,thus taking into account the intra-subject physiological variability of the artifact. Ourapproach is compared with the Average Artifact Subtraction (AAS) approach, proposedby Allen (Allen, 1998).Results and DiscussionThe AAS and the nl-AAS methods were qualitatively compared on the basis of theextracted artifact template, the single-subject average and the single-trials, in a visualdetection task (checkerboard reversal at 2 Hz). For each dataset the mean RR-intervalwas calculated (1.134 s ± 0.148 s), in order to define the duration of the time window tobe aligned.Firstly, we compared the quality of the artifact template obtained by the two approaches.The template obtained by the nl-AAS approach matches the shape of the BCGa betterthan the one obtained by the AAS method (mean absolute amplitude difference betweenthe template and the EEG fragment: 8.6 µV in AAS, 7.1 µV in nl-AAS for channel C3). Secondly, we performed a qualitative comparison of the extracted averaged ERPs interms of scalp topographies and temporal waveforms. Both methods were able to recovergood quality average data at 4T. Synchronous averaging further improved the SNR byremoving the random artifact residuals present on the single-trials, minimizing differencesbetween approaches.Thirdly, at the single-trial level, we inspected the ERP images, where the single trials areplotted one next to the other with color-coded amplitudes. We see that our proposedmAAS recovers clearer single-trial patterns, especially in the P100 window.ConclusionsWe propose and demonstrate a modified AAS approach for BCGa removal fromsimultaneous EEG-fMRI recordings at 4T. The novelty of nlAAS consists in a nonlinearalignment of the artifact occurrences before the computation of the template, whichcorrects the shrinking or stretching of the artifact over the variable RR intervals, causedby the physiological inter-subject variability of the heart beats. We showed that, whenthe single trials were considered, our method allowed the extraction of a cleaner P100component.

Diffusion-Weighted Imaging of the breast at 3T. State-of-art and personal experienceM. Lorenzon, L. Cereser, R. Girometti, A. Linda, C. Zuiani, M. MazzocchiInstitute of Radiology, Udine University, Italy

AimTo compare the diagnostic value of breast DWI and the Appearent Diffusion Coefficient (ADC)of malignant lesions at different field strenght (1.5 T and 3.0 T). To illustrate the rationale, thetechnical issues and the current clinical application of breast Diffusion-Weighted Imaging(DWI). To describe technical and clinical challenges of breast DWI at 3.0-T.







Materials and MethodsIn our preliminary experience with a 3.0T scanner (Achieva 3.0T, Philips, Best, theNetherlands), we compared breast DWI of 5 patients with known malignant breast lesionsacquired at 3.0T with breast DWI of the same patients acquired at 1.5T (MagnetomAvanto 1.5T, Siemens, Erlangen, Germany). For each patient, diffusion-weighted imagesobtained at both field strenght were scored in terms of quality (5=optimum, 4=good,3=medium, 2=sufficient, 1=insufficient), and ADC values were assessed and comparedby two radiologists in consensus.Results and DiscussionThe mean image quality value was 4 at 1.5 T and 4,2 at 3.0 T. The mean ADC value was1.08 at 1.5 T and 1,048 at 3.0 T. DWI detects changes in Brownian motion of watermolecules, hence reflecting the biologic nature of the tissues. There is evidence suggestingthat breast DWI may be a useful tool for the detection of breast cancer, the differentiationbetween malignant and benign lesions, and the assessment of response to treatment atan earlier stage as compared to morphological and dynamic criteria. 3.0-T MR scannersprovide a higher signal-to-noise-ratio, with resultant greater spatial resolution than 1.5-Tscanners, thus potentially further increasing the diagnostic sensitivity of breast MRI.However, higher magnetic strengths are accompanied by an increase in susceptibilityartifact and image distortions, due to magnetic field inhomogeneity. ConclusionsIn our preliminary experience, breast DWI performances at the moment are notsignifically different at 1.5 and 3.0 T. Although breast DWI at 3.0-T currently presentstechnical and clinical challenging issues, it seems to be a helpful tool for detecting breastcancer, especially small lesions. Further studies are needed to establish the real addedvalue of the high-field strength on breast DWI.

High-resolution resting-state network analysis at 7TE. Moser, C.Windischberger, C. Kasess, R. Sladky, V. Schoepf Centre for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria

AimBeginning with the seminal work of Biswal functional connectivity in resting-data fMRIdata has gained considerable attention [Biswal, MRM, 1995] as numerous studies haveindicated significant connectivity differences in patients suffering from neurological andpsychiatric disorders compared to healthy controls. After appropriate preprocessing tocorrect for residual motion and physiological artefacts [Weissenbacher, NI, 2009], datasets are normally smoothed in space to increase signal-to-noise ratios (SNR). Spatialsmoothing, however, causes a mixing of signals from gray and white matter, as well ascerebrospinal space. Here we examined unsmoothed resting-state fMRI data acquiredat 7T using model-free Independent Component Analysis (ICA) to investigate on the







spatial localization of resting-state fluctuations.Materials and MethodsA group of 8 young healthy subjects was examined on a Magnetom 7T scanner (SiemensMedical, Germany). Three resting-state scans were acquired in each subject using agradient-recalled EPI sequence with high spatial resolution (voxel size: 1.6x1.6x1.6 mm;TE/TR=26/2000; 40 axial slices). Each resting-state scan lasted 360s. Subjects wereinstructed to relax, stay awake, and lie still, while keeping their eyes open at all times.Data sets were corrected for slice-timing differences and motion using SPM and wereconcatenated in time for each subject. Note that data sets were neither normalized tostandard space nor spatially smoothed. ICA (including temporal low-pass filtering) asimplemented in FSL’s MELODIC was performed. The resulting ICA maps were visuallyinspected and maps corresponding to previously described resting-state networks(RSNs) were extracted [Raichle, NI, 2007; De Luca, NI, 2006].Results and DiscussionWith default parameters MELODIC uses Laplacian dimensionality estimation whichresults in over 150 components per subject based on the unsmoothed high-resolutiondata sets used in this study. Component numbers with “mdl” dimensionality estimationwere only slightly lower. We therefore chose to limit the number of ICA components to50 as to avoid excessive component splitting. Among the networks obtained withMELODIC in each of the eight subject were the “default mode network” (DMN), the visualRSN, the motor RSN and the DLPFC-RSN, respectively. Importantly, all RSN where welllocalized in gray matter and cerebrospinal space. ConclusionsThis study examined unsmoothed high-resolution resting-state data at 7T usingexploratory ICA. Benefitting from the high SNR of 7T fMRI data, it was possible to revealseveral resting-state networks. The main result of this study is that the resting-statenetworks found herein are all confined to gray matter and cerebrospinal space. It mustbe noted that not all previously described networks were consistently found in our groupof subjects. This is due to the challenges in determining the adequate number ofcomponents for ICA where to high numbers cause a splitting of networks to severalcomponents and to low number yield components with mixed resting-state networks.Although fMRI data sets were acquired with high spatial resolution, it was however notpossible to reliably quantify gray matter and cerebrospinal space resting-state networkfractions. This needs to be addressed in future studies with even higher spatial resolution.






Novel contrast mediaS. AimeDept. of Chemistry & Molecular Imaging Center, University of Torino, Italy

Molecular Imaging aims at the in vivo quantitative visualization of molecules andmolecular events that occur at cellular level. The potential towards clinical translation ishuge as the same modalities used in Medical Imaging are used in Molecular Imaginginvestigations. Traditionally, Medical Imaging was a tool for non-invasive mapping ofanatomy and for the detection and localization of a disease process. The advent ofMolecular Imaging based protocols will allow the detection of the onset of diseases atan early stage well before the biochemical abnormalities result in change in theanatomical structures. Moreover, it will offer efficient methods to monitor the effect oftherapeutic treatments. The Molecular Imaging agents provide the crucial link betweenthe specificity of the target and the quantitative visualization of its in vivo distribution.The possibility of carrying out Molecular Imaging protocols by means of MRI is veryattractive for the superb anatomical resolution that is attainable by this technique.However, MRI suffers from an intrinsic insensitivity with respect to the competing imagingmodalities that has to be overcome by designing suitable amplification procedures basedon the development of reporting units endowed with an enhanced sensitivity and on theidentification of efficient routes of accumulation of the imaging probes at the sites ofinterest. MRI definitively suffers when compared to Nuclear Medicine and Optical Imagingtechniques for the set-up of Molecular Imaging protocols as its low sensitivity implies theuse of 107-109 imaging reporting units per cell when few are necessary for the lattermodalities. Now, the need of targeting molecules that are present at very lowconcentration requires the development of novel classes of contrast agents characterizedby enhanced contrasting ability and improved targeting capabilities. Efficient targetingprocedures for cellular labeling and recognition of epitopes characterizing importantpathologies are therefore as important as the task of developing more efficient imagecontrasting units.The possibility of delivering a high number of imaging agents at the target of interestappears the solution of choice to overcome the drawback associated to the low sensitivityof the MRI approach. The use of metal-based particles entered very early in the armouryof MRI contrast agents with the Superparamagnetic Iron Oxides’ family that are stillamong the most sensitive systems. Currently much attention is devoted to the designand use of self-assembled systems based on lipophilic molecules, where the imagingreporters are invariantly represented by highly stable paramagnetic lanthanide (III)complexes. In general, whatever is the paramagnetic lanthanide (III) ion, the particlesact as T2-susceptibility agents whose contrasting abilities increase by increasing themagnetic field strength. In the case of Gd(III) complexes the systems act mainly as T1-relaxation agents whose efficiency is eventually enhanced by the long reorientational





time of supramolecular aggregates. In addition to tackle sensitivity issues, such systemsmay also be designed in order to become responsive to a specific physical or bio-chemical parameter of the microenviroment in which they distribute. Moreover nano-sized carriers for Gd-complexes based on naturally occurring systems (e.g. lipoproteins)have also been considered for targeting specific epitopes on diseased cells. Finallyliposomes’ structure has been exploited to generate a novel class of CEST agents(CEST= Chemical Exchange Saturation Transfer) dubbed LipoCEST. Such systems arecharacterized by containing a shifted resonance for the water molecules entrapped inthe liposomial cavity that can be selectively irradiated in order to transfer saturatedmagnetization to the “bulk” water signal. In this way one deals with frequency-encodedMRI contrast agents that open the interesting perspective of detecting more than oneagent in the same anatomical region. All together, the achievements made in the use ofthese nano-carriers in MRI applications represent also the basis for the development ofthe field of imaging of drug delivery processes. The superb anatomical resolutionprovided by MR images together with the availability of targeting and responsive agentswill allow the clinician to pursue the task of visualizing the delivery of drugs at thediseased region and, even more important, to monitor the therapeutic output in real time.Finally much is expected from the use of hyperpolarized molecules as it has been shownthat hyperpolarized C13-pyruvate can act as an efficient metabolic reporter for cancercells in prostate tumor bearing mice.

References:1. Terreno E., Dellicastelli D.,Viale A., Aime S., Chemical Reviews,110,3019-3042 (2010).2. Viale A. and Aime S., Current Opinion in Chemistry Biology, 14, 90-96 (2010).3. Aime S. Dellicastelli D., Geninatti Crich S., Gianolio E., Terreno E., Acc.Cem.Res., 42,822-

831 (2009).

Cerebral lesions in functional eloquent brain locationsM. Skrap, M. Mondani, S. D’Auria, F. Tuniz, R. Budai*, G. Pauletto*, M. Maieron**,S. D’Agostini***, L. Weis****, L. Fadiga****, B. Tomasino*****Unità di Neurochirurgia, *Unità di Neurologia e Neurofisiopatologia, **Medicina Nucleare,***Unità di Neuroradiologia - Azienda Ospedaliera-Universitaria, Udine, **** ITI Genova,*****IRCS “Nostra Famiglia”, Udine, Italy

AbstractAs far as lesions placed inside cortical and subcortical cerebral eloquent areas areconcerned, the issue that the surgeon have to deal with, is achieve both a widest tumoralresection and a post-operative neurological integrity. Because of lack of usefulintraoperative information provided by anatomical criteria, we are looking for functionalinformation as well. We used to evaluate the patient before the operation by mean fMRI..Neuronavigation has a consolidated role in the anatomical orientation inside the brain.





Moreover we are use to load the functional information, namely the registration of corticalevoked responses (BOLD) and corticospinal tracks (DTI) on patient’s images.Unfortunately our non-invasive effort to obtain functional data, particularly in languageand cognitive brain areas is not absolutely reliable yet, therefore nowadays direct corticalstimulation (DCS) and awake tecniques has been mandatory.

Materials and MethodsUsually in all lesions located in functional eloquent areas treated in our department weperfomed fMRI. According to anatomical and functional data we consider the signalsarising from motor and somatosensorial strep, and language area as well. Wheneverpossible, functional information have been loaded in the navigator (Stealth Station,Sofamor Danek-USA). During surgery we compared the coincidence of preoperative andintraoperative data, as a result of cortical mapping. We evaluated these data also withreference to topographical, volumetrical and istological peculiarity of the lesions.

ResultsCortical mapping has been crucial to avoid postoperative deficit. All of patients whohaven’t had a macroscopic infiltration of critical areas showed an improving ofneurological status or a stabilization of preoperative condition. Just in a few patientswhere internal capsule or motor strep were clearly involved and DCS showed us positiveintratumoral responses, we’ve seen an impairment of motor performances. Remarkablethat better results have been obtained in patients with limited structural deformation,compatible with predictable areas of positive cortical stimulation. In cases with majoranatomical deformity the coincidence DCS-fMRI has been very poor.

ConclusionsDCS routinely used before the tumour resection recognizes the critical cortical areasand allows to preserve them. Anyway, the better chance to get a good neurological resultand improvement of quality of life after the operation is coupling DCS with preoperativefMRI and neuronavigation.

Improved imaging of joints at higher fieldsS. Trattnig Centre of Excellence “high Field MR”, Medical University of Vienna, Austria

High-field MRI at 3T is rapidly gaining clinical acceptance and experiencing morewidespread use. The recent development of 3T MRI (3T MRI) has been fuelled bypromise of increased signal-to-noise ratio (SNR). Fundamentally, an increased signal-to-noise ratio (SNR) is responsible for improved imaging at higher field strength.Increased SNR allows more headroom to adjust parameters that affect image resolutionand examination time. There are, however, significant obstacles to 3T MRI presented by





the physics at higher field strengths. For example, the T1 relaxation times are prolongedwith increasing magnet field strength. Further, the increased RF-energy deposition(SAR), the larger chemical shift and the stronger susceptibility effect have to beconsidered as challenges. It is critical that one looks at both the advantages anddisadvantages of using 3T. Consequently, scanner parameters require adjustment foroptimization of images. Chemical shift and magnetic susceptibility artifacts are morepronounced and require special techniques to minimize the effect on image quality.Spectral fat saturation techniques can take advantage of the increased chemical shift.The specific absorption rate (SAR) and acoustic noise thresholds must be kept in mindat these higher fields. The ability to increase resolution for musculoskeletal imaging hasprovided previously unseen detail. Bone structure, cartilage, and tendons and ligamentscan be clearly visualized and pathology more easily detected due to an increased imagequality. Imaging applications can use the gain in signal-to-noise for increased spatialresolution or gain in speed. This comes at a trade off in increased sensitivity to fieldinhomogeneities and changes in relaxation times, which lead to changes in imagecontrast. The increase in energy deposition necessitates the use of special strategies toreduce the specific absorption rate (SAR). SAR limitations are minimized by technicaladvances and surface coils are available for all core applications. It is clear that even with current coil technology, much of the gain in signal can beharnessed effectively; however, continued coil development is necessary to realize thefull potential of 3T, especially with the optimal synergy that can be achieved with the useof parallel imaging and multiple-channel phased-array extremity coils.Furthermore, despite the theoretic imaging challenges at higher field strengths (eg,susceptibility, chemical shift, SAR, pulsation, T1 time prolongation, and T2 timeshortening), the techniques and methods that were discussed above can eliminate anyobstacles to clinical imaging. This creates excellent opportunities to improve imagequality, spatial resolution, and diagnostic accuracy in the musculo-skeletal system.Radiologists have enjoyed great success in assessing joint disease with current MRimaging field strengths; however, many intrinsic joint structures remain poorly evaluated,which leads to a good opportunity for 3T MR imaging. The articular cartilage of the hip,ankle and shoulder joint, the glenoid labrum of the shoulder and hip, the intrinsicligaments and TFC of the wrist, the collateral ligaments of the elbow and the ankle havebeen evaluated suboptimally on 1.5T systems using routine nonarthrographic MRimages. Because of the enhanced SNR, the higher spatial resolution, and the greaterCNR of intrinsic joint structures at higher field strengths, 3T MR imaging has the potentialto improve diagnostic abilities in the musculoskeletal system vastly, which translates intobetter patient care and management. New isotropic 3D-gradient echo sequences based on GRE and newly developed on FSEprovide reformatting in all planes after one acquisition without loss of resolution. At 3Tthis technique can be used for high-resolution imaging with a voxel size down to 0.5 mmin the knee joint and 0.3 mm in the ankle joint which is very promising for cartilageimaging and for the evaluation of complex meniscal tears, injuries of the cruciate





ligaments and evaluation of the femoro-acetabular impingement of the hip. New functionalcartilage imaging techniques such as T2 mapping, dGEMRIC and diffusion also benefitfrom the higher signal to noise ratio at 3T and can be performed with high sensitivity andwithin clinical acceptable scan times in patients with early osteoarthritis and in themonitoring of surgical cartilage repair procedures. Recently ultrahigh field MR has been used in musculo-skeletal imaging. Usingappropriate coils with multi-channel transmit and receive configuration even higherresolution morphological MRI of joints is possible compared to 3T within the same scantime or the scan time can be significantly reduced with the same resolution compared to3T. Furthermore the high SNR at 7T allows to perform sodium imaging of cartilage withsufficient resolution and acceptable scan times, offering noncontrast visualization andquantification of glycosaminoglycan content in articular cartilage and cartilage repairtissue, which correlates directly with the sodium content and provides information onbiomechanical properties of cartilage tissue. In summary high-field and ultra-high fieldMR imaging of the musculo-skeletal system means a another important step forward inadvanced MR imaging. Part IIMR IMAGING at 3THigh-field MRI at 3T is rapidly gaining clinical acceptance and experiencing morewidespread use. The recent development of 3 Tesla MRI (3T MRI) has been fuelled bypromise of increased signal-to-noise ratio (SNR). Fundamentally, an increased SNR isresponsible for improved imaging at higher field strength. Increased SNR allows moreroom to adjust parameters that affect image resolution and examination time. There are,however, significant obstacles to 3T MRI presented by the physics at higher fieldstrengths. For example, the T1 relaxation times are prolonged with increasing magnetfield strength. Further, the larger chemical shift and the stronger susceptibility effect haveto be considered as challenges. It is critical that one looks at both the advantages anddisadvantages of using 3T. Consequently, scanner parameters require adjustment foroptimization of images. Thus the repition time (TR) has to be increased and the echotime (TE) shortened. Doubling of the receiver bandwidth helps to reduce the chemicalshift artifact. Spectral fat saturation techniques can take advantage of the increasedchemical shift. Reduction of the voxel size and use of FSE instead of GRE sequencesminimizes magnetic susceptibility artifacts. The increased RF-energy deposition (SAR)and acoustic noise thresholds must be kept in mind at these higher fields. The ability toincrease resolution for musculoskeletal imaging has provided previously unseen detail.Imaging applications can use the gain in signal-to-noise for increased spatial resolutionor gain in speed. This comes at a trade off in increased sensitivity to field inhomogeneitiesand changes in relaxation times, which lead to changes in image contrast. It is clear thateven with current coil technology, much of the gain in signal can be harnessed effectively;however, continued coil development is necessary to realize the full potential of 3T,especially with the optimal synergy that can be achieved with the use of parallel imagingand multiple-channel phased-array extremity coils.








Furthermore, despite the theoretic imaging challenges at higher field strengths (eg,susceptibility, chemical shift, SAR, pulsation, T1 time prolongation, and T2 timeshortening), techniques and methods mentioned above can eliminate any obstacles toclinical imaging. This creates excellent opportunities to improve image quality, spatialresolution, and diagnostic accuracy in the musculo-skeletal system. Radiologists haveenjoyed great success in assessing joint disease with current MR imaging field strengths;however, many intrinsic joint structures remain poorly evaluated, which leads to a goodopportunity for 3T MR imaging. The articular cartilage of the hip, ankle and shoulder joint,the glenoid labrum of the shoulder and hip, the intrinsic ligaments and TFC of the wrist,the collateral ligaments of the elbow and the ankle have been evaluated suboptimally on1.5T systems using routine nonarthrographic MR images. Because of the enhancedSNR, the higher spatial resolution, and the greater contrast-to-noise-ratio (CNR) ofintrinsic joint structures at higher field strengths, 3T MR imaging has the potential toimprove diagnostic abilities in the musculoskeletal system vastly, which translates intobetter patient care and management. New isotropic 3D-gradient echo sequences based on GRE and newly developed on FSEtechnique provide reformatting in all planes after one acquisition without loss ofresolution. At 3T this technique can be used for high-resolution imaging with a voxel sizedown to 0.5mm in the knee joint and 0.3 mm in the ankle joint which is very promisingfor cartilage imaging and for the evaluation of complex meniscal tears, injuries ofligaments and evaluation of the femoro-acetabular impingement of the hip. New functionalcartilage imaging techniques such as T2 mapping, dGEMRIC and diffusion also benefitfrom the higher signal to noise ratio at 3T and can be performed with high sensitivity andwithin clinical acceptable scan times in patients with early osteoarthritis and in themonitoring of surgical cartilage repair procedures. In summary 3T imaging of the musculo-skeletal system means a another important stepforward in advanced MR imaging.

Diffusion-weighted magnetic resonance imaging (DW-MRI) at 3T in evaluatingwater diffusion pattern in cirrhotic and healthy livers: preliminary resultsD. Bagatto, R. Girometti, G. Esposito, L. Cereser, C. Zuiani, M. Bazzocchi Institute of Radiology, University of Udine, Italy

AimTo investigate patterns of water diffusion (isotropic vs. non-isotropic) in normal andcirrhotic livers. Methods and MaterialsTen cirrhotic patients and 10 controls underwent DW-MRI on a 3T-system. For eachsubject, a respiratory-triggered Single-shot Spin-Echo Echo-Planar sequence wasacquired, using sequential unidirectional gradients along slice, read and phase directions,respectively. Apparent Diffusion Coefficients (ADCs) of the hepatic parenchyma were


calculated for each direction using two different sets of b-values (0-400 and 0-800sec/mm2), at the portal plane.ResultsNo significant difference among slice-, read- and phase- liver ADCs was found withincontrols and cirrhotic patients (p>0.01;Kruskal-Wallis test), both at 0-400 and 0-800sec/mm2. A significant difference in mean hepatic ADCs (p<0.01) was found: (i) incomparing controls vs. cirrhotic patients at both b values sets of 0-400 sec/mm2 (1.60-3.39 vs. 0.89-0.98 x10-3 mm2/sec, respectively), and 0-800 sec/mm2 (1.00-1.17 vs. 0.63-0.64 x10-3 mm2/sec, respectively) (Kruskal-Wallis test); (ii) in comparing them withincontrols as maximum b-value increased (u-Mann-Whitney test). On the contrary, ADCswithin cirrhotic patients showed no significant differences at increasing b-values at eachgradient direction (p>0.01).ConclusionsWater diffusion in the liver, measured as parenchymal ADC, is isotropic both in controlsand cirrhotics, regardless of the b-values set used. Differences in mean ADCs betweencirrhotic patients and controls are probably related to differences in perfusion fraction ofthe signal.

Is SWI brain vessel change suitable for enhance functional activation corticalmaps?M. Maieron, S. D’Agostini, M. Skrap, B. Tomasino, R. Padovani Medical Physics Deartment, Udine University Hospital, ItalyAimFunctional Magnetic Resonance Imaging (fMRI) is the most widely used tool for brainmapping in neurosciences depicting both localization and connectivity of brain activity.A recent development of fMRI mapping is the use of spontaneous blood oxygendependent (BOLD) fluctuations to identify functionally related regions. This techniqueallows to identify all the neuronal networks even without the execution of any task.BOLDcontrast relies on the changes of paramagnetic deoxyhemoglobin concentration, whichaffects brain parenchyma and draining venous vessels. These changes indeoxyhemoglobin concentration in venous vessels can also be monitored using a high-resolution Susceptibility-Weighed Imaging (SWI) as MR-venography technique. In thestudy we want to evaluate the possibility to obtain reliable cortical activation maps usingfunctional SWI, conventional BOLD-fMRI and resting-state fMRI.Materials and MethodMRI data were acquired on a 3T Achiva Philips system from four healthy subjects. Foreach subject 5 sequences were acquired: a BOLD-EPI resting-state (rs_fMRI) run wasacquired while subjects were instructed to lay in the scanner staring at a fixation crossin the centre of the screen; two SWI gradient echo sequences were performed: oneperforming a finger tapping task and the second no task performing; a BOLD-EPI fMRIsequence was registered while the subject was instructed to perform a finger tapping in





a block design paradigm (15 s active- 15 s rest) and a T1 weighted anatomical imagewas acquired. The sequence for fMRI task–performing (tp_fMRI) and rs_fMRI sequenceshad the same parameters (TR/TE = 2500/32 ms, 28 axial slices, 3mm thickness, matrix128X128, FOV = 24 cm, number of repetitions = 260). The SWI acquisitions cover thesame brain portion acquired with fMRI but the resolution was higher with a matrix =512X512, FOV 24 cm. The fMRI runs were analyzed using FSL software. Time-series oftp_fMRI were linearly modelled with the experimental paradigm, using a GLM approachwith local autocorrelation correction, as implemented in FEAT; rs_fMRI was analyzedusing an ICA approach as implemented in MELODIC. The SWI post-processing phasefiltering was performed on the Philips workstation and the two sets of images (task –notask) were subtracted from each other to obtain an image enhancing the venous signaldifferences.Results and DiscussionThe cortical activation map assessed by analysing task-performing run and the corticalactivation map related to motor network identified from resting-state run show a strongsimilarity with 85% of overlapping pixels. In the subtracted SWI image it was possible toidentify changes in oxygenation vessel level. In a comparison between fMRI maps andthe SWI image, small venous vessels could be identified close to the areas of activationdetected by conventional fMRI showing clear coincidences of blood vessel changes withcortical activations. ConclusionsSWI technique allows a direct visualization of the BOLD-effect at high spatial resolution.In combination with conventional fMRI, this technique may help to separate thecontribution of brain parenchyma and venous vessels

DT-MR images: a CAD system for cerebral glioma and therapy follow-upG. Pastore, A. Falini, A. Castellano, M. Donativi, L. Bello, R. Soffietti

AimThe diffuse infiltration of white matter (WM) tracts by cerebral glioma is a major cause oftheir appalling prognosis: tumor cells invade, displace, and possibly destroy WM.Conventional MRI sequences (e.g. T1, T2…) have limited sensitivity and specificity indiagnosing brain tumors. Contrast-enhanced-image tumor boundaries may underestimatelesion margins, which is critical for image guided tumor resection and radiotherapyplanning. On the contrary, Diffusion Tensor Imaging (DTI) can detect abnormalities around gliomathat appear normal on conventional MRI.The aim of this study was to develop a CAD system to characterize healthy andpathological tissue by 3D texture analysis, and a method for neuroradiological follow-upof patients undergone dose-dense chemotherapy in pre-surgical setting, by a voxel-based tumor evaluation study.





Materials and MethodsDT-MR images were acquired at 3T from six healthy subjects and twenty patients withglioma (single-shot EPI sequence, b=1000 s/mm2, 32 gradient directions). Isotropic andanisotropic maps (FA, MD, p and q) were calculated, and pathological ROIs manuallydrawn.3D texture features (from the intensity and the gradient histogram, and from thecooccurrence and the run-length matrix) were calculated with a sliding window approachin the segmented ROIs and in the contralateral healthy tissue. After determining (by theirFisher-filter score) the best features for each map, the feature-space dimensionality wasreduced by Principal Component Analysis, and a neural-network classifier was trained.Glioma segmentations, performed by tissue classification, were compared with themanual ones. Automatically segmented ROIs, calculated from patients undergoing chemotherapy, werethen passed to the procedure for tumor evolution assessment. For this aim, isotropy pmaps before and after five chemotherapy cycles were coregistered and used. Each ROIreturned by the CAD system, was overlaid both to the pre-chemotherapy p maps, and tothe post-chemotherapy ones, in order to compare the same brain regions and to assesstherapy progress. A voxel-by-voxel approach was carried out, returning a plot and acolored map for each treated patient: p values of each voxel within the tumor ROI aftertherapy (p2) were plotted as a function of their pre-therapy values (p1). All tumor voxelswere classified into three classes: red-labeled voxels for which the p value considerablyincreased (with respect to a suitable threshold: p = p2 - p1>), blue-labeled voxels forwhich p decreased significantly ( p < - ), and green-labeled voxels for which the p valuesdid not change appreciably | p| <.Results and DiscussionPreliminary detection results for the p map were satisfying (ROC AUC = 0.96; 90%sensitivity and specificity; classification error 10.0%). Test images were automaticallysegmented by tissue classification; manual and automatic segmentations werecompared, showing good concordance. Segmentations were passed to the voxel-by-voxel evolution-study procedure, which gave hints on chemotherapy success. The regionsof p variation inside the tumor were electrically stimulated during the post-chemo surgery,showing good agreement with the image-processing results.ConclusionsThese preliminary results are encouraging. The medical protocol includes the study ofmore patients, and the analysis of other isotropy and anisotropy maps.

Cognitive impairment in MS: a TBSS studyC. Mastropasqua, M.Cercignani, U. Nocentini, R. Longo, M. BozzaliIRCCS Santa Lucia, Rome, Italy

Aim





It is well established that up to 65% of patients with multiple sclerosis (MS) suffer fromsignificant cognitive impairment. Different parameters have been shown to correlate withcognitive decline: EDSS scores, disease duration, depression, anxiety and fatigue.Consistent but moderate correlations between cognitive impairment and MRI measures,including T1 lesion load, T2 lesion load, diffuse brain damage, and brain atrophy havebeen reported in different studies.The aim of the present work is to establish which whitematter tracts show a correlation between cognitive impairment and fractional anisotropy(FA), an index derived from diffusion tensor imaging (DTI) that reflects microstructuralproperties of white matter.Materials and MethodsWe recruited 16 patients [M/F = 5/12; mean (SD) age = 41.754 (9.46) years; mean (SD)disease duration = 14.87 (6.53) years] with clinically definite MS (12 relapsing-remittingMS, 4secondary-progressive MS). Disability and functional impairment were assessedusing the EDSS. An extensive neuropsychological battery (Benton Judgment of LineOrientation Test; California Verbal Learning Test; Symbol digit modality test [SDMT]; PacedAuditory Serial Addition Test [PASAT]; Rey Complex Figure Test-immediate and delayedrecall) was used for the assessment of cognitive dysfunctions in MS patients. Additionally,eighteen healthy controls [M/F = 7/11; mean (SD) age = 39.16 (10.98) years] took part inthe study as control group. All subjects had an MRI scan at 3T including: fast-FLAIR (TR= 8170 ms, TE = 96 ms); Diffusion weighted EPI (TR = 7 s, TE = 85 ms, number of diffusiondirections = 61; max b factor = 1000 smm-2); 3D MDEFT (TR = 1338 ms, TE = 2.4 ms).DTI pre-processing was performed using Camino (www.camino.org.uk). Tract-based spatialstatistics (TBSS), available with the FMRIB software library (FSL, www. fmrib.ox.ac.uk/fsl/),was used to evaluate first the WM areas where patients had reduced FA compared tocontrols, and secondly to identify areas of correlation between cognitive impairment andFA values. Statistical analysis was based on permutation tests, and p-values werecorrected for multiple comparisons using the threshold-free cluster enhancement method(TFCE). The significance level was set at p<0.05.Results and discussionTBSS analysis showed the FA values to be significantly (p<0.01) reduced in MS patientsin most of white matter tracts. The only neuropsychological test showing a significantassociations with FA was the PASAT (assessing working memory), which was correlatedwith FA of the uncinate fasciculus and of the inferior fronto-occipital fasciculus in the righthemisphere. A trend to significance (p<0.06) was also found in the correlation betweenthe SDMT (assessing processing speed) and FA values of the uncinate fasciculus, ofthe inferior fronto-occipital fasciculus and of the anterior thalamic radiation of bothhemispheres.ConclusionsConsistently with previous studies, it was found that FA alterations correlate with specificmeasures of cognitive impairment in MS: processing speed and working memory areclosely associated with WM alterations of specific fronto-temporal and fronto-occipitalconnections, likely to be part of a network subserving these functions. In that sense,





PASAT and SDMT test can be considered predictors of WM alterations, providing indicesof prognostic value.

Breath-hold induced BOLD MRI signal changes in the spinal cordM . Maieron, J. Bodurka, R. Birn, C.A. Porro, P.A. BandettiniMedical Physics Department, Udine University Hospital, Italy

AimfMRI of the human spinal cord has been successfully carried out by several groups.However, questions remain regarding the contrast mechanism behind the fMRI signalchanges in the spinal cord. A contrast mechanism involving proton density changes,coined “SEEP” has been suggested that activation-induced signal changes in the spinalcord are not TE, pulse sequence or field strength dependent.It is well know that a breath-hold task causes global cerebral blood flow increases withoutincreasing neuronal activity - resulting in BOLD signal increase. In this study we use abreath holding task to determine if it is possible to elicit BOLD dependent signal changesin spinal cord, since presumably SEEP should not arise from hemodynamic changesalone.Methods and MaterialsFunctional MRI studies were carried out in 3 healthy subjects using a GE 3T scannerequipped with 16-channel digital receiver and a gradient recalled single shot EPIsequence. The subjects were instructed to perform a breath-holding task. A block designparadigm was used (20 sec breath-hold alternated with 40 sec of normal breathinglasting for 310 sec). Three runs were acquired. EPI parameters were the following:SENSE method with reduction factor=2 (phase encoding direction), TR = 2s, TE = 32ms,16 axial slices, thickness = 4 mm, gap = 2mm, matrix = 144x112, FOV = 18cm. Sliceswere placed from the spinal cord to part of cerebral cortex. Respiration trace wasexternally measured using a pneumatic belt.Images were reconstructed in IDL with custom-made software. Time-series were linearlymodelled with the experimental paradigm on a voxel-by-voxel basis, using a GLM approachwith local autocorrelation correction, as implemented in FEAT (www.fmrib.ox.ac.uk/fsl). Wecarried out two separate analysis using a block-design paradigm deconvolved with astandard gamma function (IRFS) or deconvolved with a “new respiratory response model”(IRFN).Results and DiscussionIn both analyses, during the breath-holding task a response was detected both in thespinal cord and in the cerebral cortex. The intensity of the response was much strongerin the spinal cord than in the cerebral response, also both responses show similartemporal dynamics.We found that the standard IRFS better predicts the signal changes in the spinal cordbut not so well in the cerebral cortex where the use of a new hemodynamic model help





to emphasize the signal changes breath-hold related .ConclusionsWe have observed breath-hold induced fMRI signal changes in the spinal cord.These results suggest that BOLD signal changes are present in the spinal cord withinthe context of breath-hold related signal changes. Follow-up studies using multi-echoEPI, breathold tasks and activation tasks are planned to further establish the presenceof BOLD contrast in the spinal cord.

Probabilistic fibre tracking: a possible validation?A. Moscato, N. Colombo, I. Sartori, F. Cardinale, M. Minella, A. TorresinMedical Physics Department, Niguarda Hospital, Milano, Italy

AimThe aim of this work was to preliminary validate a particular algorithm of probabilisticfibre tracking (pFT) through the combined use of functional data coming from fMRI andelectrophysiological SEEG recordings.Materials and MethodsUsually tractography is performed defining a seed and a waypoint area. In this work wedecided to start tracking process from a region established with anatomical criterion, andretained only those fibers that reached a waypoint whose definition was based uponfunctional criterion. In this way we attempted to search for some white matter (WM)pathways with specific functional role.For two epileptic patients which underwent to depth electrodes stereotactic implantationfor clinical reasons (SEEG technique), after WM reconstruction with pFT process, wetopologically correlated tracking results with electrophysiological functional informationderived from SEEG.For the first subject seeding, we anatomically defined left cerebral peduncle (l-PED) formotor fibers and ventral posterolater nucleus (l-VPL) of the left thalamus for sensitivefibers. Areas activated during a sensory-motor fMRI task (i.e. finger tapping) were usedfor hand-motor and hand-sensory functional waypoints. In the second patient we lookedfor right visual pathways. Hence we anatomically defined right lateral geniculate body forseeding (r-LGNB), while stimulation sites on primary visual cortex evoking simple visualallucinations were used as waypoints for superior and inferior portion of right OpticRadiation (r-OR).The acquisition protocol was the following: 1) 1.5T Philips Achieva MR unit (PhilipsMedical Systems, Best, The Netherlands) with 66 mT/m max gradient strenght and 180mT/m/s max slew rate; 2) diffusion weighted data acquired at b=1000 mm2/s two times(and successively averaged to enhance SNR) along 65 diffusion sensitizing directionswith SENSE factor=2; 3) a T1W3DFFE high resolution volume was acquired foranatomical comparisons; 4) cone-beam CT intraoperative electrodes imaging (O-Arm,Medtronic Inc. MN, USA).





Results and DiscussionFor the first patient we obtained two different tracts. Each one was compatible with knownanatomy. The first fiber bundle travelled fro l-PED to hand-motor cortex in the precentralgyrus, and the second from l-VPL to hand-sensory cortex in the postcentral gyrus. Thesefibers intercepted electrodes at some contacts. An electrical stimulation or an evokedpotential recordings at these contacts confirmed the goodness of pFT process. Also forthe second subject the two obtained portions of r-OR have been validated with evokedpotentials recorded at particular contacts along reconstructed fibers. Since probabilisticresults were thresholded at 95th percentile, the confidence level was very high.ConclusionsIn this work we were able to topologically correlate pFT of specific fiber bundles withfunctional information derived from fMRI and SEEG. An excellent agreement was foundbetween reconstructed tracts, known anatomy an functional informations. Due to thesmall number of subjects, we can only speak about a preliminary validation of used pFT.However important clues about goodness of acquisition protocol, image quality and entireprocedure were found.






Neuroimaging: anatomyG. BassoInterdept. Centre Mente/Cervello (CIMeC), Dept. of Cognitive and Formation Sciences(DiSCoF), University of Trento, Italy

The development of very high and ultra high magnetic resonance scanners that can beused on humans is opening new frontiers in the study of the brain. Exploiting the highersignal to noise ratio provided by these machines we can now study in detail noninvasively and in vivo both the functional and structural anatomy of the central nervoussystem. The implication of these new tools for basic research and clinical purposes arestill to be explored. However, it is important to fully comprehend the advantages and thelimitations of these new scanners in order to understand which new questions we maytry to answer.

Cortical structure observed by phase contrast at high fieldsR. PohmannMax-Planck Institute for Biological Cybernetics in Tübingen, Germany

Although magnetic resonance imaging initially results in complex data points, describinga rotation with amplitude and phase, only the magnitude of the images is usually used.At high field, the phase information becomes increasingly valuable and can be used toimprove or replace conventional contrast mechanisms. High-resolution phase imagesare able to show additional structures not visible in magnitude images.The formation of the phase contrast is explained and the postprocessing needed toobtain phase images is described. Several possible origins for phase contrast arepresented. Images from humans and rats are shown to demonstrate the possibilities ofphase imaging to depict intracortical structure.

Anatomical and spatial components in imitation of intransitive actionsR. I. Rumiati, P. Mengotti, C. Corradi Dell’AcquaCognitive Neuroscience Sector, SISSA, Trieste, Italy

IntroductionPrevious studies provided evidence that we tend to automatically imitate movementsmade by others. In particular, Brass et al. (2000) showed that we are faster when weperform a movement after having seen a similar than a different one, suggesting thatimitation is a special instance of the stimulus-response compatibility. fMRI studies usingthe same paradigm suggested that right parietal and left premotor cortices are associated





with finger imitation (Koski et al., 2003; Iacoboni et al., 1999). These finding are partiallyin conflict with neuropsychological studies in a selective deficit in imitation, called limbapraxia, typically follows left brain damage. Subsequently, Berthental et al. (2006) clarifiedthat imitation comprises of an anatomical and of a spatial component. To date no studyhas investigated the neural correlates of spatial and anatomical components of imitation. MethodsTwenty-two right-handed healthy participants took part in the study. On each trial, a videowas presented showing a left or a right hand moving the index or the ring finger.Participants performed two tasks: the Anatomical Task, in which they were asked to tapthe finger, anatomically compatible with the model, with their left or right hand; and theSpatial Task, in which they were asked to tap with their left/right hand the finger that wasspatially compatible (same side) with the model. This yielded to a 2x2x2 design with Task[Anatomical(A) vs Spatial(S)], Compatibility [Compatible(C) vs Non-Compatible(N)] andperforming Hand [Left(L) vs Right(R)] as factors. A total of 340 trials (20 null events),presented in four blocks, lasted 38 minutes. Data were collected with a 3T Philips MRIscanner and analyzed using SPM8.ResultsBehavioral results: An rmANOVA was conducted on participants’ mean RT with factorsTask, Compatibility and Hand. The significant main effects were the following; Task(p<.0001), with participants responding faster in the Spatial than to the Anatomical Task(555 vs 631ms); Compatibility (p<.0001), with responses being faster in the compatible(578ms) than in non-compatible trials (608ms), and Hand, (p<.005), with subjects beingfaster with the right (585ms) than left hand (601ms). None of the two-way interactionswas significant, whereas the Task x Compatibility x Hand interaction was significant(p<.05). Four paired-sample t-tests (with Bonferroni corrected threshold set at 0.0125)lead to the following results: for the Anatomical task, significant differences betweencompatible and non-compatible conditions for the right (t=-4.43, p<.001) and left hand(t=-4.35, p<.001); for the Spatial task, significant difference for the right hand (t=-3.75,p<.001), whereas the effect for the left hand was slightly above the corrected significancethreshold (t=-2.5, p=.02).Functional imaging resultsThe first three more extended clusters of activated voxels, which survived a threshold ofp<0.05 corrected for multiple comparisons, are reported. ***p<0.001, **p<0.01, *p<0.05.








Side Size

Task Anatomical>SpatialOccipital cortex, Superior/Inferior Parietal cortex, L 12629***Precentral/Postcentral gyri, IFG RSMA L 245***STG R 144***Compatibility Non-compatible>CompatibleSuperior/Inferior Parietal cortex R 388***Insula R 309***Precentral gyrus L 163***Hand Right>LeftPrecentral gyrus L 3309***SMA L 181***Hand Left>RightPrecentral gyrus R 2928***Rolandic Opeculum R 2155***SMA R 141***

Hand*Compatibility(comp_right>comp_left)>(non-comp_right>non-comp_left)Lingual gyrus R 2350***Superior occipital gyrus L 744***MTG R 91**Hand*Compatibility(non-comp_right>non-comp_left)>(comp_right>comp_left)Superior occipital gyrus R 554***Lingual gyrus L 84*Cuneus L 68*Task*Compatibility(comp_spatial>non-comp_spatial)>(comp_anatomical>non-comp_anatomical)Parietal operculum R 1018***Parietal operculum L 734***Inferior frontal operculum L 221***

Conjunctions (comp_spatial>non-comp_spatial)>(comp_anatomical>non-comp_anatomical) (comp_spatial>non-comp_spatial) (see Figure)Parietal operculum R 370***Parietal operculum L 302***STG R 87*(comp_spatial>non-comp_spatial)>(comp_anatomical>non-comp_anatomical) (comp_anatomical>non-comp_anatomical)MFG L 145***STG R 131***


ConclusionsAt the behavioral level, we found an effect of anatomical compatibility in the spatial taskand a comparable effect of spatial compatibility in the Anatomical task, suggesting thepresence two independent components in imitation of intransitive actions.The fMRI results highlighted the role of the Parietal Operculum bilaterally when theanatomical compatibility effect was computed, with these regions being more active inthe case of anatomical compatibility. It is suggested that the opercular regions may playa role in coding online the position of different parts of one own body compared with thatof a model.

Combining behavioral, rTMS and fMRI data in the understanding of the role of righttemporal parietal junction during emotional egocentricity biasG. SilaniLaboratory for Social and Neural Systems Research, University of Zurich, Switzerland

IntroductionEmotional egocentricity bias occurs when evaluating the emotions of others is skewedtowards one’s own emotional state – such as when we think another person is less sadthan she actually is because we are happy ourselves. It has been proposed that a lackof self/other distinction lies at the root of this bias. Previous neuroscientific findings have





associated the right temporal parietal junction (rTPJ) with processes related to self/otherdistinction when making inferences about others’ mental or emotional states. Based uponthis evidence, the present study investigated the role of rTPJ in affective egocentricitybias using a behavioral study, event-related functional magnetic resonance imaging(fMRI), and repetitive transcranial magnetic stimulation (rTMS).MethodsIn a behavioral study, we developed and validated a new experimental paradigm whichrelies upon simultaneous visuo-tactile stimulation of a participant and a target person.Stimulation elicits pleasant and unpleasant emotions which can either be congruent orincongruent between participant and target. Hemodynamic responses during trials withcongruent and incongruent emotions were acquired using a 3 T scanner (PhillipsAchieva) and analyzed using event-related statistical parametric mapping, implementedin SPM5 (http://www.fil.ion.ucl.ac.uk/spm). rTMS applied over the rTPJ (Magstim Rapid2 Stimulator, 15 min at 1 Hz) tested whether this brain region is causally related toemotional egocentricity bias. ResultsThe behavioral study revealed that our paradigm reliably establishes emotionalegocentric bias. The fMRI study showed that stimuli with positive and negative valencedifferentially recruited neural networks associated with processing positive and negativeaffect (anterior insular cortex/amygdala and medial orbitofrontal cortex, respectively).Notably, incongruent trials resulted in higher activation of rTPJ than congruent trials,which did not activate this brain region. The rTMS study established that temporarilydisturbing neuronal processing in rTPJ leads to a stronger bias during incongruent trials,compared to a control group who received rTMS of the vertex. ConclusionOur results show that rTPJ plays a crucial role in overcoming egocentric bias in thecontext of having to infer affective states of others. As a potential mechanism, we suggestthat rTPJ is involved in redirecting attention from one’s own emotional state to theemotional state of others. This process seems to be causally related to distinguishingbetween one’s own and others’ emotional states as its temporary disturbance results inan increase in emotional egocentric bias.





SESSION V – Quality assurance

Geometric accuracy, functional sensitivity and specificity: optimizationexperiences for human functional neuroimaging at 4TJ. JovicichCIMeC, University of Trento, ItalyHuman functional neuroimaging with high-field MRI is difficult. One of the most importantchallenges is due to spatial inhomogeneities in the static magnetic field B0, which leadsto both local geometric distortions (i.e., loss of spatial accuracy) and local functionalsignal loss (i.e., loss of functional sensitivity). A more general problem in fMRI is relatedto the calibration of the neurovascular BOLD signal to estimate activation that is morespecific to neuronal sources. Many methods exist to address these issues, but normallythey do not come as ready-to-use scanner-specific packages with the MRI system. Thistalk will summarize experiences in optimizing geometric accuracy (distortion correctionfrom multi-channel field maps), functional sensitivity in temporal and frontal areas(adjustment of echo time, voxel slice and slice angle) and functional specificity (CMRO2estimates from PASL and BOLD measures) on a 4T system used for human cognitiveneuroimaging research.

Quality of fMRI studiesP. FerrariUniversity of Trento, ItalyThe periodic monitoring of temporal stability during an fMRI acquisition is very importantin the routinely use of dynamic study, because the blood oxygenation-level-dependent(BOLD) fMRI signal changes are a small fraction of the raw signal intensity. The aim isto evaluate small fluctuations in the MR signal. The definition of an automatedcomputerized program for quality assurance (QA) can help in the characterization ofscanner status, point out its variations and define the lower limits and scannerperformance. The implementation of an automatic fMRI QA can determine if the scannerrequires maintenance or recalibration, since its properly performing characteristics areknown. Elements of the fMRI QA program proposed are described in the FIRST-BIRNresearch project[1]. We explain the standardized fMRI QA protocol implemented in theresearch center of Mattarello (University of Trento) were we evaluate the scanner stabilityon a 4T scanner. It is important to detect artifacts from fMRI data, not only so that they do not contaminateprocessing but also to allow researchers to alter the way the data are collected to avoidthe artifacts in the first place. One source is a “k-space spike”, a transitory event thathappens during the acquisition that causes a large change at a few isolated points in k-space. k-space spikes are usually caused by some type of scanner hardwaremalfunction, e.g., an electrical discharge, loose hardware, or “dropped” images, and it isimportant that these problems be quickly isolated and fixed.





A full description of the phantom, the QA protocol, and the calculations used to measureperformance will be provided. In particular the protocol implemented a specific fMRI QAanalysis based on the L. Friedman and G.H.Glover study[1], a specific evaluation of thespikes in the fMRI data based on the spike detection approach of D.N. Greve[2] and themanagement of the results using a dedicated web site. In the second part it will bepresented the protocols proposed during installations of multimodal setup (EEG/fMRI,TMS/fMRI, tactile stimulator/fMRI) under the quality assurance point of view.

References:1. L. Friedman, G.H.Glover, J. Magn. Res. Imaging 23:827-839 (2006).2. D.N. Greve, N.S. White, S. Gade, FIRST-BIRN, 12th Meeting of the Organization for Human

Brain Mapping, Florence, Italy, 2006.

Biophysical principles and acceptance test in MRgFUSA. Torresin, P. Colombo, S. Pasetto, F. Zucconi, A. Rampoldi, C. Ticca, A. LascialfariMedical Physics Department, Niguarda Hospital, Milano, Italy

AimDuring the last few years the use of the ultrasounds in the medical world has been notonly limited to the diagnostic field of imaging but it has extended to new methods oftherapy based on the application of high intensity focused ultrasounds. The systemMRgFUS (Magnetic Resonance guided Focused Ultrasound Surgery) is now installedat Niguarda Ca’ Granda Hospital. The aim of this work is to describe the methodologyand the problems related to this technique from a physical point of view, and tocharacterize the entire system.Materials and MethodsA system ExAblalte 2000 v.4.2, Enhanced Sonication, was installed provided by Insightec(IL) and functionally integrated with MRI GE Medical System Signa HDxt Advantage 1.5T. The system is able to combine the ultrasounds treatment capability with the MRI property.MRI is a real time control of the treatment. A focalized ultrasound wave is produced by a phased array transducer and it is directedtowards the lesion target. The intensity of ultrasounds used is much higher than fordiagnostic purpose (1000 and 6000 J) because the final aim is to increase thetemperature of the target in order to exceed the thermal dose threshold (Sapareto, 1984)of irreversible cellular damage. A single sonication is able to treat a cylindrical region with a length of about 3-4centimeters and a diameter of about half centimeter; a typical uterine fibroid treatmentmay be treated with a lot of sonications able to cover the entire volume. The MRI is used to make the treatment planning and to have a constant monitoring ofthe temperature inside and around the target. Specific MRI sequences (spoiled gradientecho) are used to have an almost real time temperature curve per pixel. The base of this





kind of MRI thermometry is the PRF shift, i.e. the shift of the resonance frequency of thewater proton due to change of temperature. In order to calibrate the MRI thermometryfor specific situation, we have investigated the relationship between temperature and thephase shift of the water proton with a heat source independent on ultrasounds and highaccuracy fiber optics temperature sensors. Another part of our work is related to qualityassurance tests with HiFU gels. These gels can change some physical properties ifheated up over a threshold temperature so that we can detect with standard MRI theareas in which temperature exceeded this value. Results and DiscussionWe made several experiments about MRI thermometry to check the technique used bythe Insightec software and to calibrate the machine under specific conditions. The resultsare very good, the linearity of the chemical shift over the temperature is strong in thetemperature range needed for HiFU treatments and we were able to calibrate the systemfor different types of tissues. We are currently using HiFU gels to compare the size andshape of the sonicated spot with the prediction of the software and the readout of MRIthermometry under different conditions.

The integration of MRI in the radiation treatment planning of localized prostatecancer E. Moretti, A. Magli, G. Como, M. Band, F. Bonutti, M. Crespi, M. Maieron, G. Brondani,M. Bazzocchi, R. PadovaniMedical Physics Department, Udine University Hospital, Italy

AimTo evaluate the MR-CT registration accuracy for the delineation of target volumes andat risk organs (OARs) in the conformal radiotherapy (RT) of the prostate canceremploying intra-prostatic fiducial markers (FMs).Methods and Materials3 gold intraprostatic fiducial markers (FMs) were implanted transrectally under US-guidance into the prostate in 15 patients with locally advanced prostatic carcinoma. Thepatients were imaged using a CT-simulator and, after soon, a 1.5T or 3T MR-scanner(T1, T2-weighted sequences). By employing markers-based procedure and an automaticregistration algorithm, CT and MR images were combined. 10-15 salient anatomicalpoints were identified within the VOI. As a measure of registration accuracy, fiducialregistration error (FRE) and target registration error (TRE) were estimated.Two observerswere asked to outline independently the prostate on CT and MR images. Daily pre-treatment orthogonal images were acquired by means an amorphous silicon electronicportal-imaging device. By localizing FMs, the portal images were matched with thecorresponding reference images and deviations were considered in the three directions.The level-action for the on-line set-up correction procedure was 2 mm.





Results and DiscussionData suggest that CT-prostate volumes are larger than MR-derived ones in agree withliterature. The registration accuracy was generally good. Average TRE was estimated2.0 mm.ConclusionsThe demarcation of the prostate gland depends on the imaging modality more than onthe observer. Due to inter-fraction organ motion, FMs-guided portal-imaging can reduceset-up margins.

Are the commercial tools embedded on MR-scanners suitable for fMRI analysis?M. Maieron, S. D’Agostini, L. Weis, R. PadovaniMedical Physics Department, Udine University Hospital, Italy

AimFunctional MRI (fMRI) is a robust neuroimaging research tool for nonivasive mapping ofeloquent brain cortices. This technique has proven to be extremely valuable in allowingto localize the representation of sensory, motor, and cognitive processes. In the last fewyears fMRI started to make the transition to the clinical field as a promising method toobtain important diagnostic or prognostic information in patients, in particular forneurosurgery planning. A problem limiting the transition is the availability of software embedded in the scannersfor the analysis. Many techniques have been proposed for statistically analysing fMRIdata and a variety of these are in general use. The aim of this study is to compare the activation maps assessed with commercialsoftware installed on the scanner machine to the activation maps obtained using more‘reaserch’ related software. Materials and MethodTwo different commercial analysis tools were tested using fMRI data obtained from 10(5+5) healthy subjects and from 10 (5+5) neurosugical patients. Data was acquired on a1.5T Avanto Siemens and on a 3T Achieva Philips scanner.In order to reproduce a realistic clinical setting, a block design paradigm was used onboth scanners. The subjects were instructed to perform 15 sec finger-tapping alternatedwith 15 sec of rest with both hands, a single run was acquired lasting for 245 sec. EPIparameters were the following: SENSE method with reduction factor = 2 (phase encodingdirection), TR = 3/2.5 s (1.5/3T), TE = 45/32ms (1.5/3T), 30 axial slices covering all brain,thickness = 4 mm, matrix = 64X64, FOV = 24cm. All the data was analysed using FSL; the data from 1.5T was also analysed using InlineBOLD Imaging, Siemens software while the data from 3T was analysed with IViewBOLD,Philips. All fMRI analysis programs use a general linear model (GLM) approach includingthe hemodynamic response function and correction for movements to evaluate thestatistics maps. Commercial software implemented a t-test parametric maps, FSL





implemented FEAT tool using FILM a robust and accurate nonparametric estimation oftime series autocorrelation to prewhiten each voxel’s time series; this gives improvedestimation efficiency compared to methods that do not pre-whiten. We evaluated thedegree of overlapping of the different maps for each subject. Results and DiscussionOur results show a good correlation between the statistic maps generated fromcommercial and free programs. This seems to assess the reliability of the estimate givenby commercial software.ConclusionsOur analysis shows that fMRI analysis can be performed with good accuracy with thesoftware provided with the consoles; this seems to indicate that this technique is suitablefor clinical routine studies.

Preliminary experience for evaluation of scanner performance and scannerstability for MRI studies at 3TM. Band, F. Bonutti, M. Maieron, R. PadovaniMedical Physics Department, Udine University Hospital, Italy

AimThe temporal stability of the MR system is essential to perform an accurate measurementof the relatively small signal changes involved in fMRI studies, based on the BOLD (BloodOxygenation-Level-Dependent) effects. In order to assure the stability of the scannerover time for fMRI studies but even for others studies (DTI, perfusion studies, etc), acontinuous quality control record of its performance is required.In this way, both improvements and defects of the MR system could potentially bedetected, consenting to operate a corrective intervention if necessary. Quality controlshould therefore provide a monitoring over time of the scanner efficiency by the periodicmeasure of some opportune parameters, on a fMRI and DTI time series of imagesacquired on a phantom. With the present work we provide a preliminary study of the performance of a 3T scanner,assessed weekly across a period of seven month (March 2010 - September 2010), basedon different methods for analyzing scanner stability. Besides the parameters proposedin the multi-centre FIRST-BIRN protocol, we evaluate the usefulness of a theoreticalmodel for the dependence of the MRI signal intensity and its fluctuations, according toTuzzi et al. In this model we selected the parameter lambda that represents a physicalmeasure of the spatial degradation of the SNR within a run. Our results suggest that theanalysis of this parameter may represent an efficient means to detect specific problemsrelated to the RM system hardware, before they manifest as severe impediments forconducting MRI studies (fMRI, DTI, dynamic studies, etc.).Materials and MethodsWe measured the stability of a 3T MR scanner (Achieva 3T, Philips Healthcare) for a





period of 7 months (the measure will go on). A time series of images was periodically(weekly) acquired on a spherical phantom (diameter=10cm) filled with 1000g of distilledH2O, 0.12g of CuSO4 x 5H2O and three metabolites using an EPI (Echo Planar Imaging)and DTI (Diffusion Tensor Imaging) sequence.Results and DiscussionWith the present work we evaluate the use of an alternative analysis of the temporalscanner stability based on Weisskoff’s method for the calculation of SNR, andconsidering a theoretical model for the dependence of the MRI signal intensity and itsfluctuations, according to Tuzzi et al. By this model we estimated, for each weeklyacquired time series, a lambda parameter, which represents a physical measure of thespatial degradation of SNR during a run.ConclusionWe provide preliminary study of the scanner stability, by monitoring lambda and severalparameters of the FIRST-BIRN protocol across a period of 7 months. Our results indicatethat the preliminary analysis of lambda is sensitive to improvements performance of theMR system and to specific hardware problems prior to actual system warnings occurred,allowing corrective intervention if necessary before they compromise the measurementitself. So, both short-term (within a run) and long-term (week-to-week or year-to-year, forstudies led over time) stability of the scanner represent a pivotal factor in advanced MRIstudies.

References:1. L. Friedman, G.H.Glover, J. Magn. Res. Imaging 23:827-839 (2006).2. Elisa Tuzzi*1et al. (in press).3. Krüger G., Glover G. H. Physiological Noise in Oxygenation-Sensitive Magnetic Resonance

Imaging Magnetic Resonance in Medicine, 46:631-637 (2001).





SESSION VI – Safety issues and regulation

Protection of patients in MRI: the position of ICNIRPP. VecchiaNational Institute of Health (ISS), Rome, Italy

The possibility of adverse health consequences of human exposure to electromagneticfields (EMF) has been widely debated in the last decades, and intensive research hasbeen carried out on biological and health effects of EMF.The International Commission on Non Ionizing Radiation Protection (ICNIRP) has issuedguidelines for the safe exposure of workers and the general public, covering the wholefrequency spectrum, from static fields to microwave radiation. These guidelines areregularly revised and updated to the advancements of scientific research. A globalrevision is in progress, and an update of recommendations for static magnetic fields waspublished in 2009. Revised guidelines for low frequency electric and magnetic fields (upto 100 kHz) are in press, while a global revision of guidelines for radiofrequencyelectromagnetic fields (100 kHz – 300 GHz) has been postponed, pending the conclusionof some important epidemiological and biological studies. However, a statement wasissued in 2009 to confirm the validity of existing recommendations.While the fundamental interaction mechanisms on which established health effects arebased have been reaffirmed by recent research, new experimental data and refinementof dosimetry have allowed a better definition of thresholds, and some reconsideration ofconservative reduction factors.According to a generally accepted philosophy of protection, the ICNIRP guidelines donot address exposure of patients during therapy or diagnostic examination. However,magnetic resonance in medicine has always deserved special attention due to the uniqueexposure modalities, and in particular the intensity of fields. Therefore, ICNIRP issuedalready in 1991 a statement on exposure of patients undergoing MRI scanning, as anaid for medical doctors in their evaluation of risks and benefits. The statement wasupdated in 2004, and further revised in 2009 to take into account on the one side therevised guidelines on static magnetic fields, and on the other side the developments ofMRI technology, with the increasing use of high-field tomographs.The presentation outlines the most recent evaluation of scientific evidence by ICNIRP,and the main features of the revised guidelines, and the implications for the protection ofpatients.

Regulation of occupational EMF exposure in MRI - where are we?S. KeevilDepartment of Medical Physics, St Thomas’ Hospital, London, Great Britain

The European Union (EU) Physical Agents (EMF) Directive(1) caused consternation in





the MRI community in Europe, because the limits in imposes on occupational exposureto electromagnetic fields (EMF) are incompatible with current and emerging MRIprocedures(2, 3). Following sustained lobbying, the EU postponed the deadline forimplementation of the directive from 2008 to 2012(4). Discussions with the EuropeanCommission are continuing, focusing on the possibility of excluding MRI from thequantitative exposure limits in the directive, subject to compliance with qualitative safetyrules. It seems likely that a further delay will be needed before the situation is resolved.This issue brought to the fore the question of how occupational EMF exposure isregulated in different jurisdictions. There are three main sources of exposure guidelinesat international level relevant to MRI.

1. International Commission on Non-Ionising Radiation Protection (ICNIRP).Covering static magnetic fields(5) and time-varying fields(6, update expected soon).

2. International Committee on Electromagnetic Safety (ICES). Covering static andlow-frequency EMF(7) and RF fields(8).

3. International Electrotechnical Commission (IEC). Covering medical device safety,including EMF exposure in MRI(9).

These organisations base their guidance on the same evidence base regarding biologicaleffects of EMF, but the exposure limits they recommend differ widely, particularly in thefrequency range relevant to switched gradients in MRI. The divergence between ICNIRPand ICES has been discussed by Reilly(10). The IEC approach, similar to ICES, aims toavoid nerve excitation. The ICNIRP limits, by contrast, are set up to two orders ofmagnitude lower, reflecting a cautious approach to limited data.The 2004 EMF Directive incorporates the ICNIRP 1998 limits. MRI workers exceed thesevalues when moving in the magnetic field around the scanner, even when it is notoperating, and when standing close to the bore during image acquisition (for exampleproviding patient care or performing an intervention)(11, 12). Although the Directive is beingamended, some countries have already made the ICNIRP limits mandatory, or have theirown national limits that also impact on MRI. In these cases, it is difficult to see how evenquite routine MRI practices can be compliant with the letter of the law.

References:1. Directive 2004/40/EC. Official Journal of the European Union L 159/1 of 30 April 2004 and

corrigenda L 184/1 of 24 May 2004.2. Hill DLG et al (2005) Acad Radiol 12 1135-1142.3. Keevil SF et al (2005) Br J Radiol 78 973-975.4. Directive 2008/46/EC. Official Journal of the European Union L 114/88 of 23 April 2008.5. ICNIRP (2009) Health Physics 96 504-514.6. ICNIRP (1998) Health Physics 74 494–522.7. ICES (2002) IEEE std C95.6. New York: IEEE.8. ICES (2005) IEEE std C95.1. New York: IEEE.9. IEC (2010) IEC std 60601-2-33 Ed 3. Geneva: IEC.

10. Reilly JP (2005) Health Phys 89 71-80.





11. Crozier S et al (2007) J Magn Reson Imaging 26 1236-125412. Crozier S et al (2007) J Magn Reson Imaging 26 1261-1277

The medical physics expert for non-ionizing radiation applications in thehealthcare environmentP. Allisy RobertsIonizing Radiation Department, Bureau International des Poids et Mesures (BIPM), Paris,France

AimThe aim of this paper is to stimulate discussion on the need for legislation addressingthe role, responsibilities and competences of the Medical Physicist in relation to the useof non-ionizing radiation for diagnostic and therapeutic procedures in the healthcareenvironment.IntroductionDirective 2004/40/EC of the European Parliament and the Council of 29 April 2004 on theminimum health and safety requirements regarding the exposure of workers to the risksarising from physical agents (electromagnetic fields) (18th individual Directive within themeaning of Article 16(1) of Directive 89/391/EEC), did not consider the use of electromagneticfields in the healthcare environment for diagnostic and therapeutic procedures.This is evident from the objections raised by a large number of European organizationsunder the umbrella of the MRI Alliance initiative, which resulted in the postponement ofthe transposition of this Directive by four years.It is apparent that Medical Physicists working in the healthcare environment were notconsulted during the preparation of this Directive. A major concern is that this may alsohold true for directives dealing with other physical agents.DiscussionAll the European Directives under the scope of Health and Safety have as their primeobjective the protection of workers and the members of the public. However, dueconsideration should also be given to the benefits for, as well as the protection of, thepatient when such directives consider physical and other agents that are used in thehealthcare care environment for diagnostic and therapeutic procedures.With regard to the physical agents used in the healthcare environment, the MedicalPhysicist is the competent scientist and should be consulted during the preparation ofsuch directives. Also, as the Medical Physicist is the competent person dealing on a dailybasis with such agents, the role, responsibilities and competences of the MedicalPhysicist must be defined explicitly in such directives in order to assure the health andsafety of the patients, workers and the public within the healthcare environment.For example, in parallel we have the Ionizing Radiation Protection Directives of theEuropean Union that define the role, responsibilities and competences of the MedicalPhysics Expert.





ConclusionThe European Federation of Organizations for Medical Physics – EFOMP, should take aleading role in lobbying the appropriate departments of the European Union to ensurethat Medical Physicists are invited to participate in the consultation process for thedevelopment of directives that impinge on the healthcare environment. The content ofsuch directives should consider the effects that restrictive measures in the healthcareenvironment may have on patients, as well as workers and the public, when physicalagents are used for diagnostic or therapeutic procedures.

Safety in high field MRI: practical aspectsR. Delia, A.A.Russo, P. FerrariBiomedical Engineering Institute, CNR, Rome, Italy

AimThe aim of this paper is contributing to formalization of some technical/practical safetyaspects in terms of risk management in MR sites, that are actually not formalized by law,but are completely under the responsibility of safety manager of the MRI system. Theconsiderations, shown in the paper, are the results of the, practical experience acquiredin the management of the 4T MR scanner, installed at the University of Trento - Italy, andvalidated by the Minister of Health.Materials and MethodsThe technical aspects discussed in present work are: 1) electrical system for the oxygenmonitoring and emergency ventilation systems, 2) ventilation air change rates. The oxygen monitoring and emergency ventilation systems of MR room should have acorrect and safe power supply system. This system should manage in safe mode thelimit condition of malfunction of the main oxygen monitoring unit: this condition shouldbe converted in an immediate activation of the emergency ventilation system. Due to thisthe main oxygen monitoring unit and the emergency ventilation system should have thesame power supply of the MR scanner (uninterruptible power supply - UPS, and/or PowerEngine) adding a normally open contact. With this technical solution, in normal workingconditions, the emergency ventilation will be activated only if, in case of low concentrationof oxygen, the main oxygen monitoring unit closes the contact of a relay. This relay willbe released, in case of a limit condition of no power supply in the main oxygen monitoringunit, and the emergency ventilation will be activated.The right ventilation air change rates is evaluated on the basis of specific emergencyprocedure for every MR site.This value warranties the possibility to operate in the worstcase of a quench in the MR room. This values are obtained considering specificparameter, like the RM room volume, the quantity of liquid Helium in the magnet Dewar,and the minimum time for evacuation of the room in case of quench.Results and DiscussionOn the basis of these parameters and of the consideration that the quench is a casual





phenomenon which cannot be described by specific mathematical laws, but can beexplained with two high occurrence probability situations, like:

1. or parabolic:not all the liquid He evaporates, with the consequence that the quenchis a multistage process like multi expansions;

2. or the quench is a transient with exponential characteristic, where the percentageof He gas produced can be calculated.

It is possible to calculate the right ventilation air change rates, necessary for themanagement of a quench. In the worst case of quench pipe out of working, consideringa minimum height in the room equal to 170 cm, the estimated time necessary for theoperator to warranty the evacuation emergency procedure of the patient from the MRroom, is 35-40 seconds, if the number of ventilation air change is equal to 20.ConclusionsBoth technical solutions, which are perfectly working, show as the knowledge of technicaland safety aspects in the MR site, improves the safety standards, and both are a validinstrument for the Responsible Expert in the MR risk management.

AcknowledgmentsSupport for this research was provided in part by the government of the ProvinciaAutonoma di Trento, Italy, the private foundation Fondazione Cassa di Risparmio di Trentoe Rovereto, and the University of Trento, Italy.

Accuracy and typical values of Specific Absorption Rate (SAR) during routine MRscanningW. Van der Putten, D.M. HickeyHealth Service Executive West, Galway, Ireland, Galway University Hospital, Galway,Ireland

AimThere is considerable interest in any possible hazard arising out of the use of MagneticResonance Imaging scanning. This is especially due to the draft “Physical AgentDirective” as proposed by the European Commission. Specific Absorption Rate (SAR)is a measure of the total energy deposited in a patient in the form of heat. Although limitshave been set for this, surprisingly little research has been done in the values which areencounterd in clinical practice. The purpose of the research presented here is twofold.Firstly the aim is to acquire a large data set of SAR values for scans typically encounteredin a busy academic hospital. This will yield a useful baseline of SAR data. Secondly, theaim is to compare the SAR values as calculated by the scanner software, with actualSAR values as measured by a calorimetric technique using an infra-red non-contactthermometer. Initial data is acquired on a Siemens Magnetom 1.5T scanner.Materials and MethodsDICOM Header data was obtained from the hospital PACS system. Scan data, pateitn





wieght and sequence information was extracted together with the reported SAR data.Total values for SAR in a series of acquisition sequences was determiend by adding theSAR values of the individual sequences together. It was verified that the intra-sequencetimes were significantly less than the thermal relaxation times of the human body.Absolute temperature measurements are made using a FLUKETM 568 infraredthermometer. This device allows for remote measurement of temperature and utilisesemmissivity correction. This was used with typical MR image quality phantoms (Perspexshell with CuSO4).ResultsAn initial retrospective analysis of n=98 patient scans was performed. The total SARestimate for each patient scan was obtained and a graph of SAR vs Patient Weight wasplotted for the various scanning modes in order to investigate how the computer modelalgorithm calculates each estimated SAR value. The vast majority of the scans (79%)were spin echo (SE), while 18% were spin echo inversion recovery (SE\IR) and theremaining are GR scans. Spin Echo scans yielded a SAR of 1.6 + 2.1 W/kg for extremityscans, 2.27 + 1.1 W/kg for head scans and 6.5 + 4.6 W/kg for whole body scans. Patientweight was 76 kg + 13 kg This data was obtained for a Siemens Symphony 1.5T scanner.Data for other scanners will be presented as will data on the temperature measurements.Discussion and ConclusionsThe recorded values of SAR for Spin Echo scans are higher than the EC standard of 0.4W/kg for whole body imaging but below those of 10 W/kg for the head (averaged over 6min) Note, that typical scan duration can exceed 6 mins by a considerable margin. It wasfound that there was no real correlation between SAR increases with patient weight foreach scanning mode, however further investigation is required, with more data, in orderto obtain how additional parameters affect SAR estimates. The aim of the temperaturemeasurements is to establish the ratio of actual to calculated SAR, which can be appliedto each calculated SAR in order to optimize imaging parameters while adhering to theproposed limits of the new EU (EMF) Directive.






Education and training of Medical Physicists - IOMP Recommendations Fridtjof NüsslinKlinik für Strahlentherapie, Klinikum rechts der Isar der Technischen UniversitätMünchen, Germany

IntroductionMedical physicists (MPs) are core members of the multidisciplinary teams in all areas ofapplying ionizing and non-ionizing radiation in health care, in particular in radiationoncology, diagnostic radiology, nuclear medicine and multimodality imaging. Theirperformance can have significant impacts on the quality and safety of these clinicalservices. As for other health professionals, medical physicists must be fully qualified withthe academic knowledge and professional skills and competency in order to be able toindependently perform their duties effectively and safely. IOMP is developing a set ofrecommendations on educational and professional qualifications of medical physicistswho are working as health professionals in medical institutions. IOMP Recommendation on Basic Education and Professional TrainingMPs working as health professionals shall demonstrate competency by obtaining theappropriate educational qualification and clinical competency training in their respectivesub-fields of practice. On basic education, IOMP recommends that this be accomplishedin two phases. The first phase of the education program is completion of a bachelor’sdegree in physics or an equivalent degree in a relevant physical or engineering sciencesubject. The second phase of the program is completion of a postgraduate program at amaster’s degree or higher level in medical physics or an equivalent degree in anappropriate science subject. On completion of the graduate program, a potential medicalphysicist is ready to undertake professional training. This should be in the form ofresidency training or an equivalent program analogous to the specialist training forradiologists or radiation oncologists. The training should usually be conducted in a majormedical institution or a cluster of medical centres in which a comprehensive range ofmedical imaging and physics equipment is available. It should be conducted under thesupervision of an experienced and competent clinical medical physicist for a duration ofat least two years. Not less than one additional year of clinical training is recommendedfor each additional sub-field.IOMP Recommendation on Professional AccreditationIOMP recommends that as a quality assurance measure on standard of practice and toqualify them to practice in clinical settings, all MPs working as health professionals shouldbe subject to professional certification, either through national professional certificationsystem or state registration. Continuing Professional DevelopmentThe continual advances in equipment technology and in clinical practice demand acorresponding evolution in the medical physics practice. MPs play an important role in





the research and development and implementation of new therapeutic and diagnosticmodalities and techniques. They should be always prepared to face such challengesthroughout their careers. IOMP recommends that every MP should be subject to anappropriate continuing professional development (CPD) program to update theirprofessional knowledge and expertise.

MRI physics education for diagnostic radiographers - an initial studyC.J. Caruana, J. CastilloBiomedical Physics, University of Malta

AimThe aim of this study was to carry out an initial survey of MRI education for diagnosticradiographers with added focus on the physics component.Materials and MethodsA review of the English language literature regarding MRI education for diagnosticradiographers was carried out. This was followed by an internet based survey ofradiography curricula in the main English speaking countries (UK, Canada, US, Australia,New Zealand) and an in-depth study of the physics component of the curricula.Results and DiscussionThe main results were:Not a single article regarding education of MRI physics for radiographers has been published.Only one significant article has been published regarding MRI education ofradiographers1. In this article the authors express grave concern that often the educationof such radiographers is largely provided simply ‘in-house’ in an ad hoc fashion by otherradiographers or applications specialists. This training is usually informal, focuses simplyon essential safety training / use of scanner software and rarely assessed. The authorsassessed theoretical knowledge and skills of a sample of 47 MRI radiographers. Themajority could not answer more than half the questions correctly and an unacceptablenumber could not practice MRI safely; very few had adequate knowledge of image qualityissues and parameter manipulation. These competences are essential for effective andsafe practice and are all heavily physics based.Physics syllabi from Universities were on the whole quite vague and gave little detail ofactual content. Recommendations regarding effective and efficient methods for pedagogicaldelivery and student assessment of this physics component were totally missing.The only comprehensive MRI curriculum (published 2008) found was that produced bya multi-organizational group consisting of representatives from the American Society ofRadiologic Technologists (ASRT), Association of Educators in Imaging and RadiologicSciences (AEIRS) and the Section for Magnetic Resonance Technologists (SMRT) ofthe International Society for Magnetic Resonance in Medicine (ISMRM)2. There is a goodphysics section which however is mostly in traditional syllabus fashion. This needs to bereformatted in learning outcome format and integrated with the other competences. There





are again no recommendations neither regarding curriculum delivery nor regardingstudent assessment of this physics component.ConclusionFurther research in MRI physics education for radiographers is required to produce aphysics curriculum as stipulated by modern curricular practices in Europe.

References:1. Westbrook C., Talbot J. What do MRI radiographers really know? European Journal of

Radiography (2009) 1, 52-60.2. ASRT, AEIRS and ISMRM/SMRT (2008) Magnetic Resonance Curriculum

https://www.asrt.org/content/Educators/Curricula/MR/mr_curriculum.aspx

EMIT project for e-training in medical imaging (MRI module)F. Milano, S. Tabakov, A. Simmons, S. Keevil, R. Wirestam F. Stahlberg Dept. Medical Eng. and Physics, King’s College Hospital London, Great Britain

The EU pilot project European Medical Imaging Technology Training (EMIT) developede-training materials on Ultrasound and Magnetic Resonance Imaging. Similarly to theirpredecessor EMERALD (dealing with X-ray Diagnostic Radiology, Nuclear Medicine andRadiotherapy), these are in 2 CD-ROM volumes with image databases, workbooks withtasks and guide. All training is separated in tasks with clearly defined timetable forimplementation.The training tasks in the Magnetic Resonance Imaging Physics e-Workbook are groupedin the following chapters with tasks:- Introduction to the MR unit. Coil systems and corresponding magnetic fields. Software,

graphical user interface, acquiring basic MR images. Patient information.- Getting acquainted with available pulse sequences - Designing and manufacturing a gel phantom for investigation of MRI signal and

contrast- MRI signal and contrast using basic pulse sequences. Influence of tissue and pulse-

sequence parameters- Image quality parameters (signal-to-noise ratio, field-of-view, bandwidth, spatial

resolution, etc.)- Basic k-space properties (simulation study)- Investigation of advanced pulse sequences- Image artefacts in MRI- Properties of contrast agents in MRI- MR angiography (MRA) and flow quantification. Pulse sequences and evaluation (MIP,

MPR, etc.)- Pulse sequences and evaluation routines in MR spectroscopy (MRS)- Overview of clinical applications








- Comprehensive quality control/quality assurance (QC/QA) program for MRI and MRS- Image file transport protocols. Network issues. MR image formats and image storage- Post-processing of MR images. Perfusion and diffusion maps. Functional MRI (fMRI)- Safety issues regarding personnel and staff. Guidelines, normal policy and legislation- Patient safety. Guidelines, normal policy and legislation- Safety regarding surrounding equipment and implants: Methods for testing the MR

compatibility of various devices with respect to ferromagnetism (translational forcesand torques), heating, image artefacts, etc.

- Commissioning and purchasing routines.Extended demos of all e-Workbooks can be viewed on the web site www.emerald2.euThe demo includes the extended EMIT Guide and some 20 pages with Trainingtimetables (all tasks with indicative time for their performance to acquire specificcompetencies). Elements of EMIT materials are now used in more than 60 countries. Its success led tothe award of the inaugural EU Prize for education – the Leonardo da Vinci Award. EMIT project partners were from King’s College London (KCL, Contractor), King’sCollege Hospital NHS Foundation Trust, University of Lund, Lund University Hospital,University of Florence, Hospital Albert Michallon Grenoble and the European Federationof Organisations for Medical Physics (EFOMP). This was the first EU project of EFOMPas an Institution and paved its way for further international projects and funding. Similarly,the newest project EMITEL included as a partner IOMP (the International Organizationfor Medical Physics) – again the first such project for the Organisation.The newest project EMITEL (e-Encyclopaedia on Medical Physics with MultilingualDictionary) can be used free from its dedicated web site www.emitel2.eu

ACTIVITIES OF NATIONATIONAL WORKING GROUPS ON MR OF EUROPEANMEDICAL PHYSICS SOCIETIES

The Institute of Physics and Engineering in Medicine. Magnetic Resonance SpecialInterest Group S. KeevilDepartment of Medical Physics, St Thomas’ Hospital, London, Great Britain

The Institute of Physics and Engineering in Medicine is the United Kingdom professionalbody dedicated to promote for the public benefit the advancement of physics andengineering applied to medicine and biology and to advance education in the field. Thetotal membership of IPEM in 2010 was 3520 including physical science, engineering andclinical professionals in academia, healthcare services and industry.The scientific activities of the IPEM are the responsibility of the Science Board, the workbeing delivered by 10 special interest groups (SIGs) covering the various disciplines ofmedical physics and engineering in including Magnetic Resonance.


The function of the SIGs are to deliver scientific meetings (conferences); provide contentfor the IPEM annual national conference; to respond to professional issues; developguidelines to improve service quality and provide expert input to external organisationsand key consultations.The IPEM MR SIG comprises 7 full members and 3 corresponding members from acrossthe UK, and meets physically 3 times per year.

MR SIG activity in 2009/2010We have established a working party to produce “Quality Assurance in MR” report toreplace the now withdrawn Report 80. This document is the de facto UK standard for MRquality assuranceWe have organised two successful national scientific meetings: the regular biennial MRSafety Update scientific meeting and Experiences and Optimisation of Multi-Centre MRIResearch Studies cosponsored by the Scottish Imaging Network (SINAPSE) and theBritish Institute of Radiology.The MR SIG is continuing to facilitate links between the IPEM with the wider communityof UK MRI scientists. We organised a joint workshop with the British Chapter of theInternational Society for Magnetic Resonance in Medicine on Research in the NHS:pathways and opportunities in 2009 and a second joint workshop on the topic ofManaging Risk in MRI Research (Nottingham September 2010).MRSIG members have been actively involved in the national MSC (modernising scientificcareers – a UK government led revision of the training and career developmentframework for clinical scientists) consultation and have contributed to three curriculum-development workshops.We remain attentive to workforce-provision issues, technological developments andparticularly all aspects of MR Safety and MRI research ethics. We have responded toconsultations and technical advice requests and are represented on the British instituteof radiology MR Safety Working Party. We are actively developing a scheme forcertification of MR Safety Advisors, in order to establish proper standards andaccreditation.

IPEM MR SIG members 2010/2011: Katherine Lymer (Chair); Anna Barnes (Secretary);Cormac McGrath, Nick Weir, Iain Wilkinson, Dan Wilson. Corresponding members: JohnThornton; Glyn Coutts; Donald McRobbie.

AIFM Work Group in Advanced Topics in Magnetic ResonanceF. LevreroGenova University Hospital “S. Martino”, Genova, Italy

AIFM is the Italian Organization for Medical Physics. The Association acts on behalf ofpeople involved in activities related to physical application in medicine, promoting and





developing scientific activities, educational events and professional updating. TheAssociation is organized in 12 Working Group, ranging from Bioethics to HealthTechnology Assessment.The working group on Advanced Topics in Magnetic Resonance was proposed inSeptember 2005, in order to bring together Physicist involved on this subject, to begin aspecific pathway for meetings and training events, to take a census of the Italian MRequipments, and to collect useful documentation for beginners.The first meeting took place in Florence, on June 5th, 2006; the initial number of theworking group members was 49, and anyone compiled a presentation form referring tothe experience level, the main topic of interest, the employed hardware and software.Several organizational meetings were held over the years. The first educational day tookplace in Florence on November 6th, 2006 and concerned on fMRI (neurophysiology,BOLD effect, signal composition, sequence optimization, statistical analisys, newmethods, complex applications) and MRS (basic topics, advanced topics). The secondmeeting was in June 15th, 2007 always in Florence and concerned with PerfusionTechniques (bolus tracking, arterial spin labeling), DICOM topics on Advanced RM,image formats and communication protocols other than DICOM, practical aspects oncommercial tomographs. The third day, in Genoa on January 12th 2010, involved apractical session on fMRI post-processing techniques, employing freeware, andcomparing the results of the post processing of several data sets.The working group licensed a procedure referring to Quality Assurance procedures onfMRI and is now discussing about similar documents on DTI and MRS. In the meantimea web page and a mailing list system were built inside the AIFM site; in the web page wecan find general documents relating the subjects of the workgroup and all thedocumentation of the meetings and of the resuming days.The current working group members number is 72, including both a dozen ones whichhad active part in the drafting of documents, in their review, in communication of resultsor in training events and the remaining people who attended to the educational meetingand accessed to the shared documentation.At Italian level an important activity is the scientific organization of a permanent Schoolof education and training for non expert Medical Physics involved in the Installation,Security, Quality Assurance of MR in Hospital site. Some members of the Group are veryactivity for teaching and experimental laboratory.







REFRESCH COURSE ABSTRACTS




Contrast mechanisms (T1 T2 T2*)M. CercignaniNeuroimaging Laboratory, Fondazione Santa Lucia, Rome, Italy

Magnetic Resonance Imaging (MRI) has become one of the most common methods ofimaging the internal organs of the human body and particularly the central nervoussystem. This is mainly due to the exquisite contrast it provides between differing tissuecompartments, such as white and grey matter, as well as between healthy andpathological tissue. Another characteristic of MRI is the possibility of manipulating nuclearspins in order to produce a large number of different image contrasts. This talk willsummarize how spin relaxation affects image contrast in MRI.The MRI signal is inherently dependent on properties of tissue collectively known as spinrelaxation. In order to understand these mechanisms, it is necessary to recall the basicprinciples of nuclear magnetic resonance, and in particular the concepts of nuclearmagnetism and magnetic resonance. Nuclear magnetism is a form of paramagnetism, meaning that all individual nuclear spinsexhibit a magnetic moment (and thus behave like little magnets), but, in the absence ofan external field, they are randomly oriented, resulting in zero net macroscopic magneticmoment.When placed in a static magnetic field, however, spins tend to align either parallel orantiparallel to the field. The two orientations correspond to different energy states. Thenumber of spins in the lower energy level (spin up) slightly outnumbers the number inthe upper level (spin down). The vector sum of the magnetization vectors from theseexcess population of spins is the net magnetization M. From a classical physics point ofview, M results from the superposition of the magnetic moments of spins precessingaround an axis parallel to the main field B0 at a frequency proportional to the fieldstrength. The precession frequency is known as the Larmor frequency, and themagnetization vector M has no transverse component because all spins precess with arandom phase. Magnetic resonance occurs when the sample is exposed to aperturbation (e.g., a radiofrequency, RF, pulse) oscillating at the Larmor frequency. Thisinteraction has 2 main effects: 1) spins tend to rephase thus originating a longitudinalcomponent of magnetization; and 2) the energy provided by the pulse allows transitionsfrom the lower energy state to the higher energy state thus reducing the longitudinalcomponent of magnetization. The relaxation times (longitudinal relaxation time, or T1,and transverse relation time, or T2) describe the time required by spins in a given tissueto return to equilibrium after the RF pulse has been switched off. T1 governs thedissipation of energy from the nuclei to the molecular environment, which enables thetransition that brings the spins back into alignment with B0 (spin-lattice relaxation). T2accounts for the interactions between neighbouring magnetic entities which cause theorientation within the transverse plane of individual spins to become randomised










(dephasing), and thus reducing the transverse magnetization (spin-spin relaxation). Bothconstants are related to the frequencies of magnetic fluctuations in the sample and thusreflect relevant information about tissue structure. Examples of pathologies where T1-weighted and T2-weighted MRI can be useful will be shown. Useful information can alsobe found in[1]. The dephasing that takes place during relaxation is accelerated by the presence ofexternal magnetic field inhomogeneities. Under these circumstances spins lose phasecoherence over time according to the time constant T2*, which is shorter than T2. Theloss of phase coherence due to field inhomogeneities, however, can be recoveredthrough the use of the spin-echo sequence, when interested in obtaining imagesweighted by T2. Nevertheless, T2* contrast also has important applications. T2* issensitive to any local change of magnetic susceptibility, and therefore can be used totrack paramagnetic contrast media (perfusion imaging)[2], or to reveal changes in bloodoxygenation concomitant to brain activations (functional MRI)[3].An important concept in MRI is that of “pulse sequence”: the pulse sequence controlsaspects of the measurement such as the timings between successive excitations, andbetween excitation and acquisition. Therefore it determines the characteristics of themeasured signal. Examples will be given on how the operator can act on the pulsesequence to obtain a specific image contrast.It is important to understand that when we talk about MRI images that are “T1-weighted”or “T2-weighted”, we mean that their contrast is made sensitive to a specific relaxationtime via a relationship which can be either direct or inverse, and typically non-linear.Therefore a T1-weighetd image is not a map of T1 values, as well as a T2-weightedimage is not a map of T2-values. In order to obtain a quantitative image of T1 or T2,typically the acquisition of more than one image obtained with differing settings of theacquisition sequence is required. This concept is the basis of quantitative MRI.

References:1. Bottomley PA, Foster TH, et al. A review of normal tissue hydrogen NMR relaxation times

and relaxation mechanism from 1-10000 MHz. Dependence on tissue type, NMR frequency, temperature, excision and age. Med Phys 1984; 11:425-448.

2. Villringer A, Rosen BR, et al. Dynamic imaging with lanthanide chelates in normal brain:contrast due to magnetic susceptibility effects. Magn Reson Med 1998: 6:164-174.

3. OgawaS, Lee T-M, et al., Brain magnetic resonance imaging with contrast on bloodoxygenation. Proc Natl Acad Sci USA 1990; 87: 9868-9872.

Basic Hardware: magnet, gradients and RF coils G. HagbergFondazione Santa Lucia IRCCS, Rome, ItalyMagnetic Resonance techniques rely on three different types of magnetic fields for signalgeneration. The magnet generates a uniform static main field, so that forms the initial







equilibrium condition of a longitudinal net magnetization in the sample and maintainsLarmor precession of nuclear spins at a constant angular frequency. Linear magneticfield gradients in 3 dimensions can be switched at and thus generate a positiondependence of the Larmor frequency. The radio-frequency (RF) coils can transmit amagnetic field of short duration in a direction perpendicular to the main field that excitesthe spins and generate transverse magnetization. As the spins return to the inditialcondition, an electromotor force is induced in the same or in specifically designedreceiving RF-coils. Besides these basic pieces, an MR system needs an appropriatehardware and software architecture in order to:control working conditions of the basic hardwaresynchronize the generation and acquisition of transverse magnetizationgenerate MR images from the acquired signal.

Image formation in MR imaging: from k-space to parallel imagingJ. BittounCIERM, Hôpital Bicêtre-Université de Paris-Sud, France

Based on Nuclear Magnetic Resonance (NMR), Magnetic Resonance Imaging (MRI)uses Radiofrequency (RF) pulses in order to measure magnetization in each elementaryvolume (voxel) of a given volume of interest. Due to their meter-long wavelengths, RFcannot be localised with such precision as X-rays in radiography. Instead, localisation isbased on the Larmor equation stating that resonance frequency is proportional to thestrength of the static magnetic field applied to create magnetization. Thus, a magneticfield whose strength is proportional to the distance in a direction, namely a magneticfield gradient, creates a linear relation between resonance frequency and distance. Inorder to localize each voxel in all 3 dimensions of space, 3 gradients are appliedaccording to 3 principles:Selective excitation consists in applying a gradient pulse during the RF pulse so thatonly the slice corresponding to the frequency bandwidth of the pulse, is excited;Frequency encoding consists in applying a gradient during acquisition of the signal. Theglobal signal of the sample thus contains a spectrum of frequencies that the FourierTransform (FT) unravels in the form of an image;Phase encoding is more complex since it consists in applying a magnetic field gradientbetween excitation pulse and acquisition of the signal. A stepwise increase of thisgradient causes a progressive dephasing of magnetization vectors that mimics, thoughin a “stroboscopic light”, the localisation principle of frequency encoding. These 3 methods are generally combined into an imaging method called 2DFT imaging.Due to the complexity of the many sequences described since the first MR image waspublished in 1973, a mathematical approach is generally preferred. In this approach, theMR scanner can be compared to a spaceship flying above k-space, defined as theFourier transform of the slice acquired. The acquisition of the image of a slice requires a




thorough scanning of the corresponding k-space. The mathematical equation shows thatimmediately after the excitation RF pulse, the MR scanner as a k-spaceship is locatedat the k-space centre; gradients Gx and Gy move the”k-spaceship” along the kx and kydirections respectively, whereas a 180° degree RF pulse “teleports” directly the “k-spaceship” to a symmetric point with regard to the k-space centre. Different acquisitionsequences can be represented by a particular trajectory in k-space.Finally, if wavelength is too large to enable localisation by RF itself, the sensitivity mapof the coil can help localizing voxels, thus decreasing the acquisition time of an image.In the so-called SENSE method, shortening the acquisition time is obtained by under-sampling k-space and unfolding the aliasing thus provoked by means of the sensitivitymaps of many coils used in parallel. In conclusion, though radiofrequency waves used in NMR cannot be localised at thescale of a voxel, the infinite number of RF and gradient pulse combinations representboth complexity and richness of MRI.










Introduction to scientific session

Radio frequency coils: basic principles and advanced applicationsM. Alecci University of L’Aquila, Faculty of Biotecnology, ItalyIn recent years, the need for higher sensitivity and spectral resolution has pushed currentMagnetic Resonance Imaging (MRI) and Spectroscopy (MRS) research towards highfield (3 to 9.4 tesla) whole-body systems.These MR scanners are proving to be very useful for a number of applications, includingquantitative proton (1H) and other NMR detectable nuclei (sodium 23Na; phosphorous31P, etc) measurements in clinical studies, such as stroke and brain tumours.A very critical hardware component is the radiofrequency (RF) coil (sensor) used toprovide RF pulses and to detect the signal of the proton and other low gamma nuclei.We review the strategies for single and double-tuned RF coils design that are suitablefor high field MRI/MRS applications(1-9).The use of single tuned RF coils as elements for parallel imaging modalities are alsodiscussed.

References :1. Vaughan JT et al, MRM 32:206 (1994).2. Zhang X et al, Proc ISMRM 423 (2003).3. Avdievich NI, USP 2005/0253581A1 (2005).4. Avdievich NI et al, Proc ISMRM 239 (2007).5. Avdievich NI et al, MRM 57:1190 (2007).6. Alecci M et al, JMR 181:203 (2006).7. Vitacolonna et al, Italian Patent RM2007A000584 (2007).8. Alecci M et al, Italian Patent RM2007A000585 (2007).9. Vitacolonna A et al, Proc. ISMRM 4751 (2009).

Origins of Image distortion and artifactsJ. Andersson fMRIB, Oxford University, Great BritainEcho-planar imaging is used to rapidly acquire images for e.g. fMRI, ASL and DTI. Theability to acquire an image in a few tens of ms, and hence full brain coverage in a fewseconds, is crucial for applications where one wants to track rapidly changing signals orwhere ... However, this ability comes at a price in terms of image fidelity.Image encoding in MRI is performed by introducing a phase to the signal by applyinggradients to give each element of the image a unique signature. In the presence of anoff-resonance field (i.e. if the field is not identical everywhere) different parts of the imagewill aquire different phase even in the absence of any applied gradients. This phase willbe proportional to the local off-resonance field and to the time since excitation. Hence,




when acquiring an echo the phase evolution will depend on the preceeding gradientsAND on the evolution caused by the off-resonance field during the acquisition of theecho. In a non-EPI aquisition a single echo is collected after an excitation, which means thatthe time during which the phase can evolve due to off-resonance effects is very shortand the distortions (along the frequency encode direction) hence typically very small.These distortions can however The different echoes (preceeded by different phase-encode gradients) are acquired at identical times after the preceeding excitation.Therefore there is no phase-evolution, and hence no distortions, in the phase-encodedirection.In contrast, during an EPI acquisition a series of echoes are collected at intervals of~0.5—1ms following a single excitation. That means that off-resonance induced phasewill accumulate for ~30—100ms yielding a total phase accumulation that is of the sameorder of magnitude as that imposed by the encoding gradients leading to highlysignificant distortions in the phase-encode direction.The off-resonance field is often caused by the object (head) itself perturbing the field by“resisiting” magnetization yielding a field that is slightly smaller than the static field insidethe object and which has a non-straightforward distribution near air-tissue junctions. Thisleads to complicated non-linear patterns of distortions in regions close to the sinusesand to the ear canals. The exact field depends not only on the object but also on itsorientation relative to the main field which means that images from different scans of thesame subject may be distorted slightly differently if the positioning is different.Another cause of off-resonance effects are eddy current-induced gradients. These arelingering after-effects of rapid gradient switching, mainly from the diffusion encodinggradients used for diffusion weighted imaging. The resulting off-resonance fields has asimple spatial distribution, being a linear combination of a constant offset and lineargradients in the x-, y- and z-directions. On the other hand it will be specific to thepreceeding gradient resulting in a set of images with different distortions.The off-resonance field will also cause other artefacts such as signal loss from trough-and within-plane dephasing and ghosting.In the lecture the mechanisms scetched above will be explained in detail, as will ways ofmeasuring and correcting for these effects. The implications for neurosurgical and/orradiotherapeutical planning will be discussed. Both in terms of dangers of mis-localizationof white matter tracts and functionally critial areas relative to pathologies and of anincreased risk for functional false positives caused by signal loss and echo-time shift.

Changes in MR physics when moving to higher field strengths: drivers formethods and technology developmentF. SchickDepartment of Diagnostic Radiology, University of Tuebingen, GermanyThis introduction wants to clarify important implications of higher magnetic field strength










for MR examinations in different regions of the human body. Advantages anddisadvantages of higher magnetic field strength for imaging and spectroscopicanatomical, functional and biochemical MR examinations are summarized. Increased field strength from 1.5 T to 3T provides nearly doubled signal yield per tissuevolume. This gain in S/N can be used either for shortening of examination time or for ahigher spatial resolution. Besides signal yield, susceptibility and chemical shift effects are doubled as well. Specificimaging techniques as T2*-weighted GRE imaging or Blood Oxygen Level Dependent(BOLD) imaging, and spectroscopy clearly gain sensitivity from higher field strengths. Since higher radio frequencies must be applied at higher field strength to fit to theresonance conditions of nuclear magnetization, field fluctuations by the RF field areclearly faster, and more energy is transmitted and absorbed by the tissue for givenamplitude of the RF field.This effect is increasing nearly quadratic with frequency resulting in a roughly fourfoldenergy deposition in the tissue at 3T compared to1.5 T, whereas wavelength is clearlyshorter (only approx. 27 cm in water at 3T). Problems due to shorter wavelength and higher RF energy deposition at higher fieldstrengths must be considered, especially in examinations of the body trunk. Somesequence types are critical regarding legal limits of specific absorption rates: For exampleRF refocusing pulses and flip angles in fast spin-echo sequences should be modified inorder to allow common multi-slice application. Longitudinal relaxation times T1 of most tissues are significantly longer at higher fieldstrength. Longer relaxation times T1 provide improved conditions for MR techniquesworking with spin preparation as arterial spin labelling (ASL) perfusion imaging or taggingexperiments as applied for functional imaging of the heart.








High Field MR applications: what can we expect?O. SpeckDept. of Biomedical Magnetic Resonance, Otto-von-Guericke University Magdeburg,GermanyThe increasing interest in MRI at high magnetic field (i.e. higher than 3T) has mainlybeen driven by neuro-imaging applications. With the more widespread availability of highfield systems many other applications benefit from the improved signal to noise ratio athigher magnetic field.However, a number of challenges have to be addressed. In tissue, the spin-latticerelaxation time T1 increases while the spin-spin relaxation time T2 is relatively constantor slightly reduced (depending on the measurement method) and T2* decreases due tothe increased local field variation. To compensate for this, obviously longer repetition andshorter echo times are required for conventional methods. Another dominant effect ofhigher field strength is the increased RF power deposition and the reduced spatialhomogeneity of the RF amplitude generated by volume transmit-coils.SAR restrictions are a main limiting factor at high field strength and have to be consideredin the sequence design. The increased frequency dispersion, which is of advantage forspectroscopic applications, also implies that off-resonance related imaging properties,e.g. the chemical shift of fat or dephasing effects in steady state sequences, increasewith field strength.In order to keep the artifact level comparable and to account for the shorter T2*, higherimaging bandwidth is needed. Correspondingly, the image noise increases proportionalto the square root of the bandwidth partially annihilating the SNR gain. On the other handthis allows acquiring more signals, e.g. more slices in the same TR. However, this simpleadaptation to higher field strength is not always possible, e.g. in situations, were thegradient strength or peripheral nerve stimulation limit the bandwidth as in EPI.In general, similar pulse sequences are used as at lower field strength.However, a number of adaptations are required. In particular, the high SAR is beingreduced by the use of longer pulses with lower (or variable) flip angles such as in theVERSE (variable rate selective excitation) and hyper-TSE methods. In general, manyresearchers prefer to use gradient echo rather than spin echo based methods at highmagnetic field. GRE methods offer high resolution, high contrast (albeit T2*) at low SARlevels in short acquisition time. Many high field applications in the brain, e.g. fMRI, pMRI,or DTI, rely on echo planar imaging. While SAR and flip angle dependence are minorissues in EPI, the increased local field variations cause markedly increased geometricimage distortions and signal loss.Geometric distortions can be as large as a few centimeters and need to be correctedbased on reference measurements. In conclusion, MR imaging at high field has been very successful over the past few yearsand many of the obstacles that were thought to be prohibitive of high field imaging have







been overcome by technical developments of the system hardware and sequenceoptimization. However, not all clinical routine methods are available for 7T at this point intime.









Guided exercise

Susceptibility-weighted imaging and data processingR. BowtellSir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Great Britain

Images based on exploiting the phase of the signal generated by gradient echosequences are increasingly being used in clinical MRI. The phase provides usefulanatomical information because it depends on the local frequency offsets which varydepending on the magnetic susceptibility of tissue. In susceptibility weighted imaging(SWI) the modulus image data are multiplied by a function whose value at each voxeldepends on the phase, and is chosen to enhance the visibility of different structures,whilst in phase imaging, appropriately processed maps of the phase variation are usedto delineate anatomical structures. In both cases, it is necessary to apply some form ofspatial high-pass filtering to the phase data in order to eliminate slow phase variationsthat do not arise from the local anatomy. It is also possible to calculate maps of themagnetic susceptibility variation from phase images by exploiting the simple relationshipbetween the frequency offsets and magnetic susceptibility that holds in the Fourierdomain. In this presentation, I will describe imaging sequences that are optimised for theacquisition of phase and susceptibility weighted images with maximum contrast to noiseratio. I will also work through the processing steps involved in data filtering and imagecombination in SWI, as well as the implementation of the calculations involved ingenerating susceptibility maps from phase images.






Safety at high field – where do we stand?S. KeevilDepartment of Medical Physics, St Thomas’ Hospital, London, Great britainThe advantages of higher magnetic field strength in terms of signal to noise, resolution,and novel contrast mechanisms has led to a surge of interest in whole body MRI systemsoperating at 7T, 9.4T, and soon at 11.7T. The use of such unprecedented field strengthsraises new safety questions for the MRI community. The magnet is the dominant feature of an MRI system, both physically and in terms ofsafety. MRI workers are familiar magnetic field hazards, principally the missile effect andinterference with biomedical implants. These problems become more acute at higherfield strength, so greater vigilance is needed. The torque experienced by a ferromagneticobject in a magnetic field is proportional to field strength, but the force depends on boththe strength of the field and its spatial gradient, which may actually be lower on high fieldsystems if they are not actively shielded. In addition, we must consider the possibility of direct biological effects of exposure tostrong magnetic fields. There are many reports of transient sensory effects, such asnausea and a metallic taste in the mouth, experienced by high field MRI workers, andthe underlying mechanisms are increasingly well understood(1). Although not harmful tohealth, such effects can be uncomfortable and can impact on individuals’ ability to workin the high field environment. They can be mitigated through appropriate training andworking practices.A number of plausible mechanisms have been suggested through which very strongmagnetic fields may have other untoward health effects. These include torque on tissueswith anisotropic magnetic susceptibility, flow potentials due to magnetohydrodynamicforces on blood, and nerve stimulation due to currents induced by movement throughthe field(2). Most of these effects would be expected to occur at field strengths higher thanthose currently proposed for human use. The World Health Organisation (WHO) hasconcluded that, apart from forces and torques on metallic objects and induction ofcurrents in tissue, other mechanisms do not appear to be of concern at this stage.However, the observation of effects on cell division in frog embryos exposed to a 16.7Tfield(3), whilst not immediately relevant to human studies, does demonstrate the realityof biological effects of strong magnetic fields and the need for a degree of caution.

References:1. Glover PM et al (2007) Bioelectromagnetics 28 349-361.2. WHO (2006) Environmental Health Criteria 232 (WHO: Geneva).3. Denegre JM et al (1998) Proc. Natl. Acad. Sci. USA. 95 14729–14732.








Index

SESSION I – Development of methods and technology for high-field MRI

Traveling wave MR___________________________________________ pag. 19

Novel motion correction techniques ____________________________ pag. 19

Novel pulse sequence approaches addressing high-field limits _____ pag. 23

SESSION II – Development of methods and technology for high-field MRI

Design of high field magnets and MR scanners ___________________ pag. 25fro biomedical use

Clinical MultiTransmit MRI - The why and the how _________________ pag. 25

Parallel transmission: current and future applications _____________ pag. 25of multi-dimensional RF pulses

Ultra High field MRI of the future _______________________________ pag. 26

Transmit/receive RF coil pair designed for ________________________ pag. 27MRI experiments on small animals at 2T

Dynamic localised 31P MRS of exercising human muscle at 7T ______ pag. 28

Optimization of BCG artifact removal for ________________________ pag. 29single-trial EEG-fMRI recordings at 4T

Diffusion-Weighted Imaging of the breast at 3T. ___________________ pag. 30State-of-art and personal experience

High-resolution resting-state network analysis at 7T_______________ pag. 31


Novel contrast media_________________________________________ pag. 33

Cerebral lesions in functional eloquent brain locations ____________ pag. 34





Improved imaging of joints at higher fields_______________________ pag. 35

Diffusion-weighted magnetic resonance imaging (DW-MRI) _________ pag. 38at 3T in evaluating water diffusion pattern in cirrhotic and healthy livers: preliminary results

Is SWI brain vessel change suitable for__________________________ pag. 39enhance functional activation cortical maps?

DT-MR images: a CAD system for cerebral glioma_________________ pag. 40and therapy follow-up

Cognitive impairment in MS: a TBSS study_______________________ pag. 41

Breath-hold induced BOLD MRI signal changes in the spinal cord ___ pag. 43

Probabilistic fibre tracking: a possible validation? ________________ pag. 44


Neuroimaging: anatomy ______________________________________ pag. 46

Cortical structure observed by phase contrast at high fields ________ pag. 46

Anatomical and spatial components in imitation __________________ pag. 46of intransitive actions

SESSION V – Quality assurance

Geometric accuracy, functional sensitivity and ___________________ pag. 51specificity: optimization experiences for human functional neuroimaging at 4T

Quality of fMRI studies _______________________________________ pag. 51

Biophysical principles and acceptance test in MRgFUS ____________ pag. 52

The integration of MRI in the radiation treatment__________________ pag. 53planning of localized prostate cancer

Are the commercial tools embedded on MR-scanners _____________ pag. 54suitable for fMRI analysis?

Preliminary experience for evaluation of_________________________ pag. 55scanner performance and scanner stability for MRI studies at 3T





SESSION VI – Safety issues and regulation

Protection of patients in MRI: the position of ICNIRP ______________ pag. 57

Regulation of occupational EMF exposure in MRI - where are we? ___ pag. 57

The medical physics expert for non-ionizing radiation _____________ pag. 59applications in the healthcare environment

Safety in high field MRI: practical aspects _______________________ pag. 60

Accuracy and typical values of_________________________________ pag. 61Specific Absorption Rate (SAR) during routine MR scanning


Education and training of Medical Physicists_____________________ pag. 63IOMP Recommendations

MRI physics education for diagnostic radiographers ______________ pag. 64an initial study

EMIT project for e-training in medical imaging (MRI module) ________ pag. 65

ACTIVITIES OF NATIONATIONAL WORKING GROUPS ON MR OF EUROPEAN MEDICAL PHYSICS SOCIETIES

The Institute of Physics and Engineering in Medicine. _____________ pag. 66Magnetic Resonance Special Interest Group

AIFM Work Group in Advanced Topics in Magnetic Resonance ______ pag. 67







Contrast mechanisms (T1 T2 T2*)_______________________________ pag. 71

Basic Hardware: magnet, gradients and RF coils__________________ pag. 72

Image formation in MR imaging: from k-space to parallel imaging ___ pag. 73


Radio frequency coils: basic principles _________________________ pag. 75and advanced applications

Origins of Image distortion and artifacts_________________________ pag. 75

Changes in MR physics when moving___________________________ pag. 76to higher field strengths: drivers for methods and technology development


High Field MR applications: what can we expect? _________________ pag. 78

Guided exercise

Susceptibility-weighted imaging and data processing _____________ pag. 80


Safety at high field – where do we stand?________________________ pag. 81






Note
























Documents

Advances in High Field Magnetic Resonance Imaging · General Information Conference Venue Auditorium Hypo Group Alpe Adria Bank Via Alpe Adria, 2 33010 Tavagnacco, Udine Italy Participants’