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Magnetic Resonance Imaging at 7T
in Glasgow
A unique opportunity!
An NHS MR Physicist's perspective...
• What is different about 7T scanners?
• What has already been achieved?
• Imaging Centre of Excellence (ICE)
– What's different about this site?
• Research opportunities available.
• Ensuring MR safety
What is different about 7T scanners?
Over 4 times stronger than existing
standard clinical scanners
These are not routine systems.
There are a limited number of
manufacturers.
Imaging coils are often not standard
and even bespoke.
Stronger magnet, more energy, more
signal.
Shajan Gunamony, now at UoG
Examples of what is possiblefrom other clinical research sites
Professor Chris Hess, UCSF School of Medicine
GE 7T installed since 2006
Early Work - Comparing 3T & 7TT2* GRE - 6.5 min scan,
same parameters, 0.35 x 0.35 x 2.0 mm
Chris Hess, UCSF
3T 7T
Early Work - Pushing Spatial Resolution0.250 mm in-plane, 2 mm slice
Line of Gennari
Chris Hess, UCSF
From Susceptibility to Phase ContrastPhase Yields 10-fold Improvement in CNR over
Conventional MRI
Chris Hess, UCSF
3T 7T
Microscopic SusceptibilityT2* Contrast
MagnitudePhase Phase
χ<0 χ>0
Diamagnetic Paramagnetic
MagnitudePhase Magnitude Phase
B0 B0
Chris Hess, UCSF
Improved Depictionof Steno-occlusion
Closer Approximation to Catheter Angiography
7T
3T DSA
Chris Hess, UCSF
Multi-band 7T NODDI: Low Grade Glioma
OD Viso Vic Vec
T1+ T2 FLAIR ADC FA
Qiuting Li et al, UCSF
Clinically feasible (5.5 minute) diffusion modeling of brain tissue
Getting the best out of 7Tbalance benefits with challenges
• Benefits of 7T:
– Signal (to noise ratio SNR), T1 and T2 relaxation,
– Chemical Shift (for spectroscopy)
• Challenges of 7T:
– Specific Absorption Rate (SAR), RF Uniformity
– Ergonomics, Motion correction/detection
– Susceptibility
Siemens Magnetom Terra
First research 7T system designed for future clinical use.
Although weighing 25 tons it is about half the weight of previous designs!
Siemens Magnetom Terra
After Erlangen, Wurzburg and Cambridge,
Glasgow will have the fourth in the world of this new design system.
It will be delivered on 27th November 2016 – just before St Andrew’s Day!
Research and DevelopmentIntroducing ICE
Clinical lead for research
“For my own specialism in stroke, the 7T MRI
scanner will allow us to produce detailed images of
the damage caused by stroke and give us the
capability of visualising the very small vessels
responsible for many strokes.”
Prof Keith Muir
“What sets Glasgow’s 7T scanner apart from those at other sites.. indeed internationally – is that it will be housed at a hospital.”
“Most other facilities.. handle patients who can walk into a university research building, but we’ll ..bring patients in their beds from the hospital into the ICE building to use the scanner.”
Prof Keith Muir
Clinical lead for research
Direct from patient bed-sideto scanner table
• The ICE building has been designed to ensure that the 7T imaging facility is completely integrated within a university hospital campus allowing direct access to the 7T from all patient groups.
• Other sites around the world are in separate research sites remote from the hospital or if nearby still requiring transport.
Connectivity.....
Learning & Teaching Building, Innovation Floor
Main Acute Hospital
Clinical Research Facility
Imaging Centre of Excellence (ICE)
Unique partnerships on site
• This facility unlocks the potential for ultra high field MRI based clinical research within the hospital campus.
• This facility has been made possible by a “triple helix approach” of partnership between the University of Glasgow, NHSGGC and Siemens.
A truly national resource
• The Imaging Centre of Excellence will bring together teams of clinical researchers, industry and academics.
• It will build on strong collaborations already existing at 1.5T and 3.0T
• There is now a strong desire in the industry to drive 7T to clinical especially since the static field limit is now 8T.
• Initial focus will be head but this will develop to other areas.
Translational research
• Ensuring the research activity reaches the patient is a role that NHS Researchers are well placed for.
• The NHS MR Physics Group is part of this...
• It comes with the same software platform as clinical 3T and 1.5T models aiding translational research between field strengths..
• The scanner is expected to be operational from April 2017
7T enables…
At a sub millimetre resolution;
– Structure
• Variations in myelin and iron content
– Function
• Grey matter and white matter
• Variations in signal across the cortex
– Connectivity
• rsfMRI at 1mm isotropic
• Layer based fMRI responses
Provided subject motion correction or detection
strategies can be utilised!
• Accurate RF modelling is critical
• Importance of inter-site site comparison to confirm image quality and RF deposition.
Ensuring MR Safety
• The use of numerical simulations on generic models remains the most widely used SAR evaluation method.
• Different safety factors are typically added to account for coil modelling errors, anatomic variability and uncertainties associated with the monitoring hardware.
• SAR and temperature can now be explicitly taken into account in pTx RF pulse design.
• Thermal dose likely to prove to be even more useful metric.
Ensuring MR Safety
• Establish live patient RF safety modelling and pTxoptimisation to increase feasibility of clinical research neuro scanning at 7T and other body areas by collaborating with appropriate sites.
• Many MR conditional implants are not yet tested to 7T and so accurate modelling is required. Sites such as MDC in Berlin have done extensive work on this.
Maintaining safety…
UK 7T
• This will provide a UK network with Glasgow taking a lead on patient safety.
• A standardised head imaging protocol will be set up.
• Develop exchange programmes with major 7T sites such as Oxford, Cambridge, Nottingham, Cardiff, as well as international sites.