Somatom sessions 32

Answers for life in Computed Tomography

SOMATOM Sessions

Issue Number 32 / June 2013

Cover Story True Dual Energy SucceedsPage 06

News Saving Dose, Reducing Patient BurdenPage 12

Business Maximum Single Source Performance for High-end Cardiac ImagingPage 20

Clinical ResultsFree-breathing Coronary CTA with Double Flash Spiral ProtocolPage 32

Science Finding the Right Dose with the Right ToolsPage 40

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2 SOMATOM Sessions · June 2013 · www.siemens.com/SOMATOM-Sessions

Editorial

Cover page: Courtesy of Erasmus Medical Center, Rotterdam, the Netherlands

“We see our role as supporting institutions in achieving the right dose that delivers high diagnostic image quality while exposing the patient to only as much dose as required.”

Peter Seitz, Vice President Marketing, Computed Tomography, Siemens Healthcare, Forchheim, Germany

SOMATOM Sessions · June 2013 · www.siemens.com/SOMATOM-Sessions 3

Editorial

Dear Reader,

In this issue you’ll read about the inroads that Dual Energy imaging has made and continues to make in CT routine today. At centers such as Grosshadern Hospital at the University of Munich, more than 50 percent of all abdominal scans are now performed using Dual Energy. And while back in the early days in 2005 Dual Energy was limited to Dual Source scanners, Single Source applications as found on the SOMATOM® Definition Edge are becoming standard. And in radiation therapy planning, Dual Energy can help to reduce metal artifacts.

Moreover, its use in combination with the latest Dual Source technology delivers highly valuable additional information even for delicate patients; for example when imaging infants with congenital heart or lung disease. Recently, research-ers from Japan have also shown the positive impact on oncology treatment decisions in complicated structures of the neck.

Some months ago, I introduced our shift in focus from the lowest dose to the right dose in CT. In this issue, you’ll find more examples of institutions that use the entire current portfolio of dose reduction techniques to achieve average dose val-ues that are constantly and significantly below the reference values of national authorities. Of course, a permanent reduc-tion in average dose values is what really counts – as impressive as a single low dose case can be.

CARE kV does this by making it very easy to use the lowest possible kV setting, especially in small patients with low attenuation, and in contrast examinations where lower kV settings provide better iodine display. SAFIRE does this by mak-ing powerful noise and therefore dose reduction available with reconstruction times of merely a few seconds. When you combine both with the hardware-based noise reduction of the Stellar Detector, you’ll be surprised how far your average dose values can drop.

So that we can share even more exam-ples, we’re launching the third round of our CT image contest in June – focusing on the right dose in CT. The Right Dose Image Contest 2013 will once again be supported by a jury of globally renowned experts, this time consisting of members of SIERRA (Siemens Radiation Reduction Alliance). Across several categories, they will choose the institutions that best demonstrate how they achieve images at the right dose for an ideal balance between diagnostic quality and low radi-ation. For the first time, a new category will be given for consistency in dose reduction. And you’ll have the opportu-nity to present your finest cases to the world on your own profile page.

Enjoy these and many more topics in this issue and don’t forget to check out our SOMATOM Sessions App.

Best regards,

Peter Seitz, Vice President Marketing,

Computed Tomography, Siemens Healthcare, Forchheim, Germany

Peter Seitz

In clinical practice, the use of SAFIRE may reduce CT patient dose depending on the clinical task, patient size, anatomical location, and clinical practice. A con-sultation with a radiologist and a physicist should be made to determine the appropriate dose to obtain diagnostic image quality for the particular clinical task.


Cover Story

Content

Cover Story

06 True Dual Energy Succeeds

News

12 Saving Dose, Reducing Patient Burden14 FAST Spine – A Story of Best Practice

in Spine Reconstruction16 Rib and Spine Assessment in Acute

Care with syngo.CT Bone Reading16 Right Dose Image Contest 201317 Expanding the Clinical Portfolio with

the Siemens Intervention Solution18 Unique Technology for Improved

Routine and New Research Opportu-nities

06 Radiologists and technicians across the globe are breaking new ground in CT imaging with Dual Energy (DE). SOMATOM Sessions talked to four leading experts about their clinical experiences in routine and research areas, the possibilities for sharper contrast, significant metal artifact reduc-tion, and new prospects on the horizon.

16 Right Dose Image Contest 2013

xx xxxx Siemens International CT Image Contest 2011

Business

20 Maximum Single Source Performance for High-end Cardiac Imaging

Clinical Results

Cardiovascular22 Coronary CTA with 80 kV: Improving

Image Quality with Reduced Radiation and Contrast Medium Dose

24 70 kV CT Pulmonary Angiography in an Adult Patient with a Dose of < 1 mSv and PA Attenuation of > 1,000 HU

26 Dual Source CT: Assessment of Hypoplastic Arch Associated with Ductus Arteriosus

28 Cardiac CT in a 5-Month-Old Baby with VACTERL Syndrome after Cardiac Surgery

12 Saving Dose, Reducing Patient Burden

Content


Science

40 Finding the Right Dose with the Right Tools

43 New Opportunities in Cancer Detection with Hepatic AEF

44 Image Quality in Computed Tomography

Customer Excellence

48 syngo Evolve Update for SOMATOM Definition Family Members

49 Workshop on Dual Energy at CT Headquarters in Germany

49 CT Physics Made Easy – with New Webinar

30 Evaluation of Femoral Artery Pseudo-aneurysms with Arteriovenous Fistula using CTA Runoff Scanning

32 Free-breathing Coronary CTA with Double Flash Spiral Protocol

Oncology34 Squamous Cell Carcinoma of the

Head and Neck: Volume Perfusion CT36 Diagnosis of Rectal Tumor using

SOMATOM Perspective

Neurology38 Dose Reduction in Head CT

Examination using SAFIRE

50 Tips & Tricks: How to Accelerate Reconstruction of Dual Energy Data

51 Clinical Workshops 201351 Upcoming Events & Congresses 2013

52 Subscriptions

53 Imprint

32 Free-breathing Coronary CTA with Double Flash Spiral Protocol

24 70 kV CT Pulmonary Angiography

40 Finding the Right Dose with the Right Tools

Content


Cover Story

True Dual Energy Succeeds Radiologists and technicians across the globe are breaking new ground in CT imaging with Dual Energy. SOMATOM Sessions talked to four leading experts about their clinical experiences in routine and research areas, the possibilities for better contrast, significant metal artifact reduction, and new prospects on the horizon.

By Wiebke Kathmann, PhD

Exciting technical innovations in com-puted tomography imaging continue. Dual Energy (DE) scanning in particular has been expanding rapidly since it became available for the first time on a commercial multislice CT scanner. Back in 2005 DE was introduced to the market on the Dual Source CT scanner SOMATOM® Definition.More and more radiologists rely on True Dual Energy CT from Siemens due to remarkable features such as:1. Improved diagnostic options2. No extra dose with Dual Source Dual

Energy scans3. Applicable to almost all clinical

challenges and most patients

Beyond morphologyTrue DE supplies additional information compared to a conventional CT scan for Dual Source DE and dose optimized for Single Source DE. In conjunction with high spatial and temporal resolution, DE applications are used to great effect both in routine clinical practice and research. DE is most widely applied to characterize material, e. g. in kidney stones or gout. Dual Source DE is also well established in heart imaging that is prone to motion artifacts due to breathing and movement of the beating heart. In the meantime,

True Dual Energy is also available on the Siemens Single Source CT scanner fleet ranging from any configuration of the SOMATOM Definition AS to the SOMATOM Definition Edge. And progress continues: other applications are now also making their way from research into clinical practice. Four experts describe how they

integrate DECT in their daily routine and outline their research interests.

Munich, Germany: Research into Single Source DEAt University Hospital Munich, Campus Großhadern, Germany, there always has been a strong focus on DECT imaging.

“We are working on the Single Source scan mode because I am convinced that Single Source DE allows a spe-cific and quantita-tive assessment of iodine uptake.”

Thorsten Johnson, MD, University Hospital Munich, Campus Großhadern, Germany


Cover Story

Today, about 50 percent of all abdominal CT examinations are routinely performed with DE. As one of the clinical innovators of Dual Source CT applications, Thorsten Johnson, MD, explains that their experi-ence has mostly been with Dual Source DE. He has been involved since the early days and co-developed many algorithms along the way. At present, his research focuses on Single Source DE on the SOMATOM Definition Edge. If the differ-entiation of cancerous lesions and blood filled cysts was possible this application would have broad clinical relevance and would be of great interest to a range of users, for instance oncological centers.The different behavior of iodine uptake may help distinguishing between cysts, which do not enhance, and iodine uptak-ing lesions. Johnson’s team is working on the Single Source DE scan mode as he is convinced that Single Source DE scan mode on the SOMATOM Definition Edge might also be very specific for iodine as on the Dual Source scanners. “Usually, if you want to quantify the iodine uptake of a lesion, you perform scans with and without contrast medium. With the Single Source DE scan mode on the SOMATOM Definition Edge you can perform two scans directly consecutively at half dose with the benefit of the additional DE.” Johnson’s team has had promising initial

results in recent cases with excellent image quality at a low dose level (Fig. 1).

Rotterdam, the Netherlands: DECT in infants – no sedation with no dose penaltyOnly recently, experts from the cardio-vascular imaging group at the radiology department at the Erasmus Medical

Center in Rotterdam, the Netherlands, started using Dual Source DE in pediatric scans. Their goal: To enable well-founded treatment decisions based on anatomical and functional information without the need for sedation or anesthesia, or indeed without increasing radiation dose. As senior radiologist Mohamed Ouhlous, MD, PhD, explains, the purely anatomical information supplied by conventional CT is not sufficient for children with con-genital heart and lung disease. “We also need quantitative information, for exam-ple on ventilation and perfusion, for the pediatric cardiologist and pulmonologist. Therefore, we started to explore other imaging modalities. We were convinced that DECT could give us the additional information required once we discovered that DECT can create images of perfu-sion defects in adults with lung emboli. These are generally hard to see, because of the many collaterals. My reasoning was: If you can quantify the blood flow in the lung, why not use it in children with congenital heart and lung disease?”Step by step the team developed a pro-tocol on the SOMATOM Definition Flash. First, they replaced the regular CT scans with Flash scans and noticed that they could reduce the need for sedation for

1 DECT of a liver with a hypodense mass. The case was acquired with SOMATOM Definition Edge. Courtesy of University Hospital Munich, Campus Großhadern, Germany

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“With Dual Source DE, potential problems can be discovered ear-lier and with greater precision, helping improve a patient’s quality of life.”

Mohamed Ouhlous, MD, PhD, Erasmus Medical Center, Rotterdam, the Netherlands


Cover Story

their young patients. Even on crying infants, they could perform the scan between breaths without artifacts. The result: Pediatricians requested CT scans more often. After some initial experi-ence with these young patients using the Flash protocol, the team moved on to the issue of lung perfusion, i.e. visual-izing iodine distribution of the lung.Since December 2012, the Erasmus team has scanned twelve children and infants, the youngest being one-day old, with Dual Source DECT. The image quality has surpassed everyone’s expectations. The clinicians in particular were excited. “Dual Source DECT scans provide them with extra information on abnormalities that the clinician might not see in the ultrasound examination. Nowadays, they want the CT before they start with an angio so they have a certain roadmap,” says Ouhlous. Compared with angiogra-phy, DECT not only has advantages in iodine and radiation dose, it is also non-invasive using intravenous rather than intra-arterial contrast application. And it may potentially help reduce the risks with

sedation or anesthesia that some other techniques entail. Ouhlous concludes that good information can be gained by Dual Source DE techniques. Therefore,

Dual Source DE is used regularly for this specific group of patients and is now an accepted imaging tool for congenital heart and lung diseases that might

2 Scan of a 7-month-old child with congenital heart defect using 1.4 mSv effective dose. The patient was scanned with SOMATOM Definition Flash (Dual Source DE) and evaluated with syngo.CT DE Lung Analysis (syngo.via VA20).Courtesy of Erasmus Medical Center, Rotterdam, the Netherlands

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3 Negative cartilage invasion of the thyroid cartilage imaged with DECT in a 65-year-old man with hypopharyngeal cancer (weighted average (WA) image, Fig. 3A; iodine overlay (IO) image, Fig. 3B). Courtesy of National Cancer Center Hospital East, Chiba, Japan

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Cover Story

affect the children later in life. Potential problems can be discovered earlier and with greater precision.

Chiba, Japan: Dual Source DE may avoid overtreatmentAnother pioneer of DECT in oncological radiology, Hirofumi Kuno, MD, is staff radiologist at the National Cancer Center Hospital East in Chiba, Japan. As a spe-cialist in head and neck oncological radi-ology – especially laryngeal and hypo-pharyngeal squamous cell carcinoma – he sees many patients with these some-what rare cancers. Hoping to avoid over-treatment of his patients, he was looking for a CT application that could reliably discriminate between laryngeal cartilage and iodine-enhanced tumor tissue. In con-ventional CT images, both have roughly the same CT values making them hard to distinguish. Clinically, however, it is essential to clarify whether there is thy-roid cartilage invasion when deciding on treatment options.This is where DECT comes into play. Kuno saw the potential of DE in distinguishing iodine-enhanced tumor and cartilage in CT imaging using syngo.CT DE. “I’m not interested in the technology per se, but in the benefits for the patient,” Kuno states. “The benefit of DE is clearly the positive impact of the high quality images on the treatment decision. It allows precise diagnosis of the cancer in spite of the complicated structures in the neck and the diversity of appearance, which often leads to false positive results. Here, it can make the difference between organ-conserving therapies (chemo radi-ation) and more aggressive treatments (laryngectomy), which potentially have a major impact on a patient’s quality of life due to a possible post-surgery loss of voice.“As soon as the SOMATOM Definition Flash was installed at the hospital in March 2010, Kuno began his work. In close col-laboration with Siemens, he developed a scan protocol and investigated whether it led to improved diagnostic performance. Little difference was noted in reconstruc-tion time and image evaluation com-pared with conventional CT scans. The program prepares the weighted average

(WA) and iodine overlay images (IO). The WA image allows the evaluation of the cartilage (invasion, erosion, lysis or lysis plus extralaryngeal invasion). The second contrast – i. e. the enhancement pattern on IO images – enables the dis-tinction of uptake due to the blood ves-sels of the cancer tissue as opposed to blood vessel free cartilage.“By 2012, we had scanned around 300 patients with laryngeal or pharyngeal cancer. T4 stage is invasion throughout the cartilage which, according to guide-lines, calls for laryngectomy. We are con-vinced that in this patient population the tumor could be downstaged to T3 using CT scans with higher resolution. That should result in a decision to pursue function-preserving treatment”, says Kuno. He found that using Dual Source DECT improved specificity and sensitivity in detecting the extent of cartilage inva-sion. The results of his study were pub-lished in the journal Radiology in October 2012.[1] Kuno’s conclusion: “Combined analysis of WA and IO images obtained with DECT improves the diagnostic per-formance and interobserver reproduc-ibility of evaluations of laryngeal cartilage invasion by small cell carcinoma. This is of the utmost importance for the treat-

ment strategy, especially when attempt-ing a function-preserving therapy.”Meanwhile, Kuno examines most of his head and neck cancer patients using Dual Source DE. The technology has made its way from research to clinical routine in just two years and is now an established protocol. “This was possible as DE scans always include the normal 120 kV image so that nothing is lost – no extra dose is applied. The only difference is the need for more disk space to archive the images. For the technician, DE scans do not affect the workflow,” explains Kuno. “Also, the time required for the scan and the iodine dose is the same for the patient.” He truly believes that T4 staging of laryngeal and pharyngeal cancers may become much easier for non-specialized institutions. “From our perspective, any institution with a SOMATOM Definition Flash can start using Dual Source DE protocol for head and neck tumors from one day to the next.”

Hamburg, Germany: Excep-tional image quality with DE – a must for radiation planningAt ‘Radiologische Allianz’ – an associa-tion of practices focusing on radiology, nuclear medicine and radiation therapy

“From our perspective, any institution with a SOMATOM Definition Flash can start using Dual Source DE pro-tocol for head and neck tumors from one day to the next.”

Hirofumi Kuno, MD, National Cancer Center Hospital East, Chiba, Japan


Cover Story

with nine locations in Hamburg – experts are now using DECT scanning. Their interest is in metal artifact reduction, a major issue in radiation therapy. DE helps in planning radiation therapy for patients with head and neck cancers, cancers of the pelvis, or prostate cancer. In these patients metal artifacts are a challenge as preceeding treatments using metal such as seed implantation of 25 to 80 small metal radiation emitting pins, in patients with prostate cancer, endo-prosthesis of the hip or implants in the mouth cavity affect CT images. “All these metal implants create white stripes and make it hard to draw the precise outline, for example of the lymph drainage path-ways in the mouth,” explains Matthias Kretschmer, medical physicist. “The radi-ation therapist can no longer define the target volume, and the medical physicist can no longer predict the precise radia-tion dose needed. Single Source DE produces more accurate images for the radiation oncologist and helps the physi-cist to calculate his dose estimate using more reliable data. Just as with real estate, what counts in CT images is loca-tion, location, location. We can only hit

the tumor precisely if the location of the patient under the linear accelerator is exactly the same as in the previous plan-ning CT,” stresses Kretschmer.When the Hamburg team started out, they were still using conventional CT

scans; they compared the results with those from a Single Source DE scan with a SOMATOM Definition AS 20 Open. This was necessary as the Hounsfield Units (HU) change as a result of the mono-energetic application. New correlation

“If a topogram depicts metal implants, we replace the conventional CT with a Single Source DE scan.”

Matthias Kretschmer, MSc, Radiologische Allianz, Hamburg, Germany

The Single Source DE scan mode consists of two successive automated spiral scans at different tube voltage (kV) and tube current (mA) levels. Each scan is performed at approximately half the dose which confidently comply with the ALARA principle.

DEfinitely excellent images: Crisp image quality Information beyond morphology –

highlight, characterize, quantify, and differentiate material

DEfinitely the right dose: No dose penalty with full number

of projections All dose saving features applicable

such as SAFIRE and CARE Dose4D

Dedicated protocols and evaluation software applications for various clinical questions

Low radiation and contrast media dose – applicable for virtually all patients from pediatric to older patients

Single Source DE: The Scan Principle

1st scan

2nd scan

140 kV

80 kV

True Dual Energy


Cover Story

4 Metal artifact reduction with Single Source DE Monoenergetic: Conventional CT (Fig. 4A); Monoenergetic image at 120 keV (Fig. 4B) The patient was scanned with SOMATOM Definition AS20 (Single Source DE) and evaluated with syngo.CT Dual Energy (integral part of syngo.via VA20 advanced user). Courtesy of Radiologische Allianz, Hamburg, Germany

tables for each monoenergetic mode used in artifact reduction had to be calculated on the phantom and stored in the plan-ning software. In Hamburg, the team has the benefit of having Julia Sudmann, PhD, a medical doctor and radiation therapist in training on the CT. She can immedi-ately assess the location from the topo-gram and predict whether hampering metal artifacts are to be expected. In this case, conventional CT scans are no lon-ger performed. Instead, the application is immediately switched to a Single Source DE scan. After only a few runs, treatment planning improved in 60 percent of cases where Single Source DE application was used, Sudmann recalls.A decision on whether to use Single Source DE is made according to the individual case with the location of the tumor in relation to the implant being the strongest determinant. Based on the scans performed so far, Sudmann finds

Single Source DE has clear advantages for tumors in the mouth base. “For these patients we will be using Single Source DE as standard from now on.” She sees a sensible application in patients with prostate cancer and with permanent seed implants who have a biochemical relapse – that means an increase in the PSA value – and who need repeated external radiation. “Overall, we will most likely use it in about five percent of our patients with head and neck or pelvic cancers who have endoprostheses or implants.”To be successful in clinical practice, DE needs to deliver excellent image quality, no dose penalty, and broad applicability to virtually all patients. The experiences of these four CT experts described in the interviews show that True Dual Energy does just this. It is not only well estab-lished in the field of research but even more important in daily clinical routine.

Further Information

www.siemens.com/dual-energy

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Medical writer Wiebke Kathmann, PhD, is a frequent contributor to medical magazines for physicians of German-speaking media. She holds an MSc in biology and a PhD in theoretical medicine and has worked as an editor for many years before becoming freelance in 1999. She is based in Munich and Karlsruhe, Germany.

The statements by Siemens customers described herein are based on results that were achieved in the customer’s unique setting. Since there is no “typical” hospital and many variables exist (e.g., hospital size, case mix, level of IT adoption) there can be no guaran-tee that other customers will achieve the same results.

Reference[1] Kuno H et al. Evaluation of cartilage invasion

by laryngeal and hypopharyngeal squamous cell carcinoma with dual-energy CT. Radiology. 2012 Nov;265(2):488-96.


News

Saving Dose, Reducing Patient BurdenA plucky physician from St. Louis and technological advances by Siemens are working together to cut dose levels in pediatric patients to unprecedented levels.

By Ron French

It’s difficult for Marilyn Siegel, MD, to keep a smile off her face these days. For years, the pediatric radiologist at Washing-ton University School of Medicine and St. Louis Children’s Hospital has been leading a campaign of words and research to lower dose exposure in children. Her story is one of success, and it is one shared by the complete line of Siemens computed tomography equipment.

Spreading the low-dose gospelIn the United States alone, more than 70 million CT scans are performed each year – double the number of a decade ago. But even with today’s technology, the radiation dose of those scans has a deleterious cumulative effect on patients – particularly the pediatric patients Siegel works with each day in St. Louis, Missouri, USA: “Effective dose in children is three to five times higher than in adults at com-parable exposure levels,” she said. The low dose advocate travels around the globe speaking to physicians about the importance and methodology of dose reduction: “Even for one-time exams, you want the dose low. But it’s particularly important for patients who come back for multiple examinations; they’re going to start accumulating dose. Lung trans-plant patients are an example.”The goal is to reduce dose, while main-taining or improving image quality. Today, technology is catching up with Siegel’s vision.

The next step in ‘exquisite images’The Siemens SOMATOM® Definition AS, 64-slice configuration, has been the hospital’s workhorse for four years. It is a Single Source scanner, featuring leading technologies, like real-time dose modula-

tion CARE Dose4D or the Adaptive Dose Shield to avoid spiral over-radiation, both crucial for pediatric scanning. Recent upgrades to the machine have taken dose reduction to new lows. In 2011, Siemens upgraded the SOMATOM Definition AS, 64-slice configuration to include CARE kV, which automatically adjusts voltage to match body size and scan type. CARE kV supplements CARE Dose4D to a complete automated exposure control for an opti-mal balance between diagnostic image quality and lowest possible dose.Siegel was the first in the United States to use CARE kV on children. “The results were amazing,” she said. “The mean dose reduction was 30%. In smaller patients, it could be up to 50%.”“If you looked at all our patients – from 2 kg to 120 kg – we were getting 6 mGy; under 50 kg, we were down to about 5 mGy,” Siegel said. “I was remarkably

impressed. The contrast was maintained, and the dose went down 30%. We were under 1 mSv, with exquisite images. I was amazed the first time I saw it.” Accord-ing to the pediatric radiologist, CARE kV was a step forward: “The biggest impact has been on contrast-enhanced and angiographic imaging. But across the board, in any procedure, it has had an impact,” she pointed out.Siegel recalls the case of a 3-year-old girl with heart disease who had undergone multiple operations: “We wanted to see anatomy,” she explained. “We did a CT with no sedation at 70 kV, with a dose of less than 1 mSv and got outstanding images.”

Quicker iterative reconstruc-tion (IR) with reduced noiseThe success story continued in 2012 with the installation of Siemens Sinogram

At Washington University School of Medicine and St. Louis Children’s Hospital Marilyn Siegel, MD, has been leading a campaign of words and research to lower dose exposure in children.


News

Affirmed Iterative Reconstruction (SAFIRE). SAFIRE removes artifacts and noise from scanned images. Because radiologists are trained to read images with some noise, the technology means that milli-amperage can be lowered to the point that an “acceptable” level of noise is in the image, reducing dose in children by as much as 60%.SAFIRE also provides a vastly improved IR performance thanks to enhanced image reconstruction computing power and smartly engineered signal process-ing. In other models, IR can take up to 45 minutes to reconstruct a patient’s data set; with SAFIRE, reconstruction takes only seconds to a few minutes. In pediatric CT, Siegel was the first to use CARE kV in combination with SAFIRE. The results stunned the physician: the overall mean radiation dose of scans fell from 8.3 mGy to 4.5 mGy – roughly equivalent to annual background radia-tion. Milligray values in CT Angiography scans dropped from 6.2 to 2.8; Chest abdomen pelvis scans plummeted from 10.5 to 4.8. “The real issue out there is dose, but you also have to have great image quality,” Siegel pointed out. “The goal is to get to less than 1 mSv with pediatrics at good diagnostic image qual-ity. This technology is helping us get there.”

The Gold StandardWhile Siegel has already shown herself able to perform excellent image quality at a very low dose with the 64-slice con-figuration of the SOMATOM Definition AS, she wanted to go for Siemens high-end scanner, the SOMATOM Definition Flash. The Flash is the gold standard of com-puted tomography, with all of the fea-tures of the AS 64-slice configuration but with two tubes and detectors and thus much faster acquisition speed. “Tradi-tionally, most of our CT imaging has had a pitch of 1.2 to 1.5,” Siegel said. “We couldn’t go past 1.5 because soon you weren’t radiating enough of the patient to get an image. With the Flash, we can scan much faster. When we use it for congenital heart disease, we use a pitch of 3.4. We can scan in less than a second and reduce the radiation dose again. We

can use pitches of 3.0 or 2.8 for all our exams, with an incredible effect on dose. The major advantage for everyone is reduction in sedation and reduction in breathing artifacts,” Siegel said. “If you have healthy kids coming in for their first chest and abdomen exam, you don’t need to give sedation if they can stay still for a second or two. It has improved the quality of the exam and reduces burden on patients.”Using the high-pitch scan modes of the Flash and with its built-in CARE kV, along with the 20% reduction in milliamperage reconstructed with SAFIRE, Siegel was able to realize even greater dose savings: “The overall mean of all scans was reduced to 2.7 mGy,” she said.The SOMATOM Definition Flash also facil-itates the new Stellar Detector, which limit electronic noise. The Stellar Detector delivers a spatial resolution down to 0.30 millimeters without increasing dose. This provides improved images of vessels, for example.

Getting closerIn the fall of 2013, Siegel will head for Germany to work with Siemens engineers on the next step in pediatric imaging: making Dual Energy scans dose-neutral. “If I can show that the dose stays low, then it becomes an exciting tool,” Siegel said. “Pretty pictures alone don’t do it. It will help in areas that we so far haven’t evaluated, like vessel perfusion in the

In clinical practice, the use of SAFIRE may reduce CT patient dose depending on the clinical task, patient size, anatomical location, and clinical practice. A consulta-tion with a radiologist and a physicist should be made to determine the appropriate dose to obtain diagnostic image quality for the particular clinical task. The follow-ing test method was used to determine a 54 to 60% dose reduction when using the SAFIRE reconstruction soft-ware. Noise, CT numbers, homogeneity, low contrast resolution and high contrast resolution were assessed in a Gammex 438 phantom. Low dose data reconstructed with SAFIRE showed the same image quality compared to full dose data based on this test. Data on file.The statements by Siemens customers described herein are based on results that were achieved in the customer’s unique setting. Since there is no “typical” hospital and many variables exist (e.g., hospital size, case mix, level of IT adoption) there can be no guarantee that other customers will achieve the same results.

lung and heart together, and assessment of tumor response by tracking iodine. The bottom line is: It’s going to allow functional imaging that we haven’t done before with CT.”Siegel and Siemens aren’t finished yet. She proudly displays a chart showing the incredible dose savings that are pos-sible when the SOMATOM Definition AS 64-slice configuration is combined with CARE kV and SAFIRE. Above the chart are the words: “We are getting closer.” “It’s exciting,” Siegel said, smiling. “You can affect lives.”

Ron French is a freelance business and medical writer based in Detroit, Michigan, USA. He also writes for the Detroit News.

“ The goal is to get to less than 1 mSv with pediatrics at good diagnostic image quality. This technology is helping us get there.”

Marilyn Siegel, MD, pediatric radiologist at Washington University School of Medicine and St. Louis Children’s Hospital, Missouri, USA.


News

FAST Spine – A Story of Best Practice in Spine ReconstructionSOMATOM Definition AS boosted by FAST Spine provides a remarkably accel-erated workflow in spine reconstruction. In the department of radiology at the Centre Hospitalier Universitaire de Tivoli (CHU Tivoli), an affiliation of the Université Libre de Bruxelles, Belgium, the specialists are impressed by the ease of use, the speed and the quality of the automated spine reconstruction.

By Ruth Wissler, MD

The radiology department at CHU Tivoli performs about 92,000 CT examinations per year. The radiological staff consists of 15 radiologists and about 22 technicians. Almost a quarter of the examinations are orthopedic and spinal CTs.The hospital is focused on neurosurgical interventions. About 30% of the patients are referred for spinal examination by gen-eral practitioners or surgeons from other clinics. Since their SOMATOM® Definition AS+ was equipped with FAST Spine from the end of March 2012, it has been used there in almost all clinical cases of back pain, sciatica and herniated discs.“Since we installed FAST Spine on our SOMATOM Definition AS+ system, all of my clinical staff have been very enthu-siastic about the user-friendly software. The technicians are more independent, and we, the doctors, can concentrate on the interpretation of the clinical images,” mentioned Pietro Scillia, MD, head of the Department of Radiology at the Centre Hospitalier Universitaire de Tivoli in Bel-gium.

Benefits of FAST Spine support clinical imaging routinesConsiderable time-saving is one promi-nent clinical feature. FAST Spine allows faster setup and preparation of spine reconstructions, including automatic labeling. Immediately after the data acqui-

1 FAST Spine delivers an automatic segmentation of the spinal canal and automatic labeling of the vertebrae. Courtesy of University Hospital of Zurich, Switzerland

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Ruth Wissler, MD, studied veterinary and human medicine. She is an expert in science communications and medical writing.

sition, FAST Spine automatically starts detecting the spinal vertebrae, and labels them according to their anatomical posi-tion. FAST Spine then uses this informa-tion for typical reconstruction modes for the spinal vertebrae or discs. Time-critical spine examinations also benefit from the high reproducibility of the reconstruc-tions. “With FAST Spine we were able to increase the number of exams by about 20% per day,“ says Pietro Scillia. “It is very convenient to use and we employ it in almost all orthopedic cases. Even with difficult spine patterns, the automated detection works.”

FAST Spine helps to reduce reimbursement challenges The department of radiology plays an important economic role for CHU Tivoli,

“ With FAST Spine we were able to increase the number of exams by about 20% per day.”

Pietro Scillia, MD, Head of the Department of Radiology at the Centre Hospitalier Universitaire de Tivoli, Belgium

with just 6% of the hospital’s doctors contributing almost 15% of the overall profits. In this situation, the department is particularly dependent on an effective CT system, as the relatively low reim-bursement also has to pay for the device purchase. “That is an enormous challenge for us,” says Scillia. “We are basically dependent on a well working system with an effective workflow, because we want to perform very good exams and not just a lot of exams.”The specialists’ experiences at CHU Tivoli with SOMATOM Definition AS+ boosted by FAST Spine tell a story of best practice in radiology by accelerating workflow and increasing number of exams per day.Due to its significant clinical benefits, Siemens has also extended the avail-ability of FAST Spine to the SOMATOM

Perspective Family and will introduce it for the SOMATOM Emotion* Family in the last quarter of 2013.

* Under development. Not available for sale in the U.S.



News

Rib and Spine Assessment in Acute Care with syngo.CT Bone ReadingBy Philip Stenner, PhD, Computed Tomography, Siemens Healthcare, Forchheim, Germany

Right Dose Image Contest 2013By Ivo Driesser, Computed Tomography, Siemens Healthcare, Forchheim, Germany

Following the success of the image con-tests held over the past few years, Siemens Healthcare has decided once more to invite radiologists and radiographers from across the world to take part in the latest round of this international competition.Again a jury of experts, this time consist-ing of members of SIERRA (the Siemens Radiation Reduction Alliance), will choose in eight different categories the institu-tions who best demonstrate how they achieve images with the right dose for an ideal balance between diagnostic quality and low radiation.From June 2013, any clinical institution or hospital with a CT scanner from the SOMATOM® Family can once again sub-mit their best images to be shown on the contest website.

1 syngo.CT Bone Reading displays the entire rib cage rolled on a 2D planar reformat. Courtesy of University Hospital Salzburg, Austria

1 Coarctation of aorta. Winning image 2011, category “Vascular”, by Liz D’Arcy, Wexford General Hospital, Ireland.

Trauma cases with suspected multiple injuries to the thorax and spine call for a complete and reliable evaluation of the ribs and vertebral bodies. Diagnosis of possible fractures needs to be available very quickly. Simply scrolling through axial slices while trying to focus on the point of interest can be very time-consuming due to the oblique orientation of the ribs.syngo.CT Bone Reading revolutionizes rib and spine assessment: The application identifies and labels the ribs, and displays curved 2D images of the entire rib cage on a multi-planar reformat. In addition, the vertebral bodies are labeled and the spine is presented in an unfolded view for a straightforward overview of the anatomy. Thanks to the “Automatic Pre-Processing”, the case is ready to be

reviewed immediately on opening.The planar display of the rib cage facili-tates the direct detection of lesions, e. g. fractures of vertebral bodies or ribs. When the user clicks on a fracture, the system centers the axial, sagittal, and coronal views on the area of interest to allow a detailed assessment.The system also provides cross sections of the spine orthogonal to the unfolded view and updates the position along the spine while scrolling in real time.In conclusion, syngo.CT Bone Reading can effectively increase speed in bone assessment.

A new element this year is the fact that sustainable dose management at the participating institution will also play a role in the evaluation of the images. Indeed, there will even be an additional category for the entrant with the best dose reduction strategy.“The many hundreds of submissions we’ve had in the past few years clearly demonstrate that our customers enjoy presenting their work to a global audi-ence and having it discussed by a spe-cialist community,” explains Peter Seitz, Vice President of CT Marketing.

www.siemens.com/ct-acute-care

www.facebook.com/imagecontest www.siemens.com/imagecontest

1

1


News

Expanding the Clinical Portfolio with the Siemens Intervention SolutionBy Jürgen Merz, PhD, Computed Tomography, Siemens Healthcare, Forchheim, Germany

The number of therapeutic interventions using CT has increased considerably over the last few years. More complex proce-dures can be performed faster, with bet-ter outcomes, fewer complications, at a lower cost and with less discomfort for the patient.

Increasing markets for minimally invasive therapyAs the number of indications for mini-mally invasive therapy increases, more and more CT scanners are used for this purpose; sometimes even exclusively. Today, for example, interventions are performed on one third of SOMATOM® Definition AS scanners.* The clinical spectrum ranges from CT-guided biop-sies, through pain treatment (particu-larly in the spinal region) and drainage of inflammatory processes, to ablation of tumors in the lungs, abdomen and pelvic area.

Standard intervention features on the SOMATOM Definition FamilySiemens recognized this trend at an early stage, invested significantly in this area and today offers an intervention solution for its CT systems that is highly valued by clinicians. Among the SOMATOM Definition Family (AS, Edge, Flash) basic 2D interventional features are already part of the standard configuration as well as HandCare, a radiation reduction feature for the operator.

Advanced intervention solu-tion for dedicated individual and clinical needsAs interventional procedures become more and more complex, doctors develop more sophisticated and highly individu-alized workflows. Consequently, Siemens advanced solutions allow the adaption

and optimization of the workflow to the individual need and the clinical setting. “Intervention Pro” allows the operator to switch between spiral, sequential and fluoroscopy protocols on the fly, while the in-built “Layout Editor” enables the screen layout to be specifically adapted to clinical questions or personal prefer-ences (e. g. 3D layout for spinal inter-ventions or the additional display of MR images). The “Adaptive 3D Intervention” package provides the option of planning and conducting the intervention com-pletely in 3D. Immediately after the scan, the operator is provided with coronal, axial and sagittal views in his specific layout. Needle path planning in both 2D and 3D and a needle detection algorithm provide high-quality results. “i-Needle

sharp” solves the challenge of metal artifacts from the needle. “i-Fluoro” (CT fluoroscopy) allows the person perform-ing the intervention to track the interven-tion instrument in real time during the procedure. An optional foot switch and an additional control unit (i-Control; wire-less, if desired) enable the surgeon to work directly on the patient completely independently. The package is rounded off by a variety of measurement and analysis tools. These options can also be purchased together as a package – the “Adaptive 3D Interventional Suite” – pro-viding the operator with a fully equipped interventional CT system.

1 Radio Frequency Ablation Therapy in a patient with lung cancer with SOMATOM Definition AS+. Courtesy of Department of Radiology, University of Munich, Grosshadern, Munich, Germany

1

* Data on file


1 Fig. 1 shows images from a DE Angiography examination of the thorax that was included in a study:[1] Original poly-chromatic images at 80 kV, 140 kV, mixed image at 120 kV (upper image series), and 3 of 6 mono-chromatic reconstructions at levels of 60 keV, 70 keV and 100 keV (lower image series). The central vessels could best be assessed at lower keV levels (60 keV); the reconstruction at 100 keV provided best con-ditions for the systemic veins. Courtesy of Hospital Calmette, Lille, France

News

Unique Technology for Improved Routine and New Research OpportunitiesTwo exclusive Siemens technologies, Dual Source Dual Energy CT and the Stellar Detector, take routine applications to a new level and open up opportunities for innovative research.

By Heidrun Endt, MD, Computed Tomography, Siemens Healthcare, Forchheim, Germany

Dual Source Dual Energy CTIn 2012, the American Journal of Roentgenology (AJR) published a special supplement on Dual Energy CT (DECT). Several review articles outlined the current status of scientific research and different approaches to DECT. An important state-ment in the supplement declared that: “Of the various methods that have been proposed for acquiring DECT data, image acquisition based on DSCT [Dual Source CT] is the most intensely evaluated approach in the current literature.”[1] Has this also been transferred to use into daily routine?

Researchers from Université Lille Nord de France state that this technique can be used for chest CT Angiography exa-minations for routine diagnostic evalua-tion.[2] Examinations were carried out on 80 patients using Dual Source Dual Energy on a SOMATOM® Definition Flash with a reduced amount of iodine (170 mg/mL). In addition to images at 80 kV and 140 kV, further monoenergetic images (50/60/70/80/90/100 keV) were reconstructed using syngo Dual Energy. Monoenergetic images at 60 keV were the best choice for the assessment of cen-tral vessels, images at 100 keV for the

systemic veins. These images at 100 keV also presented with reduced perivenous artifacts, known from conventional CT examinations. Researchers compared all these with single energy CT images, acquired with a standard dose of contrast medium. According to the study DECT examinations offered adequate image quality for the systemic veins with the advantage of considerable reduction in the amount of iodine contrast used.[2] In addition the evaluation of the central vessels was not degraded, which is the limitation of single energy CT with reduced contrast media administration.[2]

80 kV

60 keV 70 keV

120 kV

100 keV

140 kV

1


2 A 63-year old male patient underwent coronary CT Angiography examination. This examination was included in a study.[3] Fig. 2A was conventionally reconstructed with 0.6 mm slice thickness. For Fig. 2B, 0.5 mm slice thickness was used in combi-nation with SAFIRE strength 3. The latter enabled a more precise evaluation of the stenosis and therefore a more precise quantification. Courtesy of University Hospital Zurich, Switzerland

2A 2B

One review article in the AJR supple-ment described DECT for head and neck imaging.[3] According to the review there are several established applications for different body regions, for instance the chest and abdomen. The experience for the use for the head and neck region is limited so far, but “early results are promising, and further research is encour-aged.”[3] A study by researchers in Japan also suggests further potential of DECT (see also Cover Story).[4] Here, DECT was used to evaluate the invasion of the laryngeal cartilage in 72 patients with laryngeal and hypopharyngeal squamous cell carcinoma (SCC). The cases were read either with weighted-average images alone – which are comparable to con-ventional CT images – or in combination with iodine-overlay images. The com-bined reading enabled a full exploitation of the possibilities of DECT. A concluding statement by the authors illustrated that DECT improves diagnostic confidence and interobserver reproducibility.[4]

The Stellar DetectorThe Stellar Detector, introduced in 2011, offers clinical benefits for a range of applications, including coronary CT Angiography. Researchers at University Hospital Zurich, Switzerland, assessed these benefits using a SOMATOM Definition Flash.[5] In their study they began with an evaluation of a particular coronary phantom simulating different stenosis and plaque densities. These

scans were performed twice: once with the Stellar Detector and once with a conventional detector. Subsequently, these findings were confirmed clinically in the second part of the study. Coro-nary CT Angiography was carried out on 30 patients using a SOMATOM Definition Flash equipped with the Stellar Detector. Conventional detector technology can reconstruct images with a slice thickness of 0.6 mm, whereas the Stellar Detector in combination with SAFIRE enables a slice thickness of 0.5 mm. By comparing the two different reconstructions, the authors conclude that with the new technology image noise is significantly reduced and stenosis quantification could be done more accurately.[5]At the German Heart Center, Munich, Germany, coronary CT Angiography examinations acquired before (group B) and after (group A) the installation of the Stellar Detector were compared.[6] Each group had 20 patients and the examinations were performed using the same protocol (100 kV, 370 mAs). The groups were matched in terms of age, sex and BMI to allow comparison. Images acquired with the Stellar Detector and reconstructed with SAFIRE in group A had an impressive noise reduction of 30%.[6]

OutlookIn their chest CT Angiography study, researchers from France recommend the routine use of DECT for this applica-tion.[2] As well as evaluating clinical

References[1] Henzler T, et al. AJR Am J Roentgenol.

2012 Nov;199(5 Suppl):S16-25.[2] Delesalle MA, et al. Radiology.

2013 Apr;267(1):256-66.[3] Vogl TJ, et al. AJR Am J Roentgenol.

2012 Nov;199(5 Suppl):S34-9. [4] Kuno H, et al. Radiology.

2012 Nov;265(2):488-96. [5] Morsbach F, et al. Invest Radiol.

2013 Jan;48(1):32-40. [6] Deseive S, et al. Scientific presentation at ECR

2013: Impact of a new detector technology (Stellar, Siemens Healthcare) on image noise in coronary CTA, B-0372.

images, they also made full use of the potential for contrast media reduction.[2] Yet, many clinical questions are still waiting to be answered in more detail with DECT – as shown by the study from Japan.[4]This is also the case for the Stellar Detec-tor. There are proven benefits of using the Stellar Detector in coronary CT Angi-ography examinations that are routinely performed all over the world.[5, 6] However, further research is needed on the impact of the Stellar Detector, for example in stent imaging, an application that shows promising initial results in scientific studies.While these exclusive technologies – Dual Source DECT and the Stellar Detec-tor – open up new research opportuni-ties, they continue to benefit everyday clinical routine.

News


Business

Maximum Single Source Performance for High-end Cardiac ImagingFor the Clinique Bizet, when it came to choosing a new CT scanner – size mattered. This Parisian clinic sits amid some of Europe’s most valuable real estate. With space at a premium and a team unwilling to compromize on performance, the clinic found that the Siemens SOMATOM Definition Edge offered the ideal solution.

By Bill Hinchberger

Tuesday at the Clinique Bizet: With near-clockwork efficiency, one after another, patients are ushered into a small room just 23-square meters for CT scans. Even a patient with his complete equipment, a bed from the intensive care unit and five people working to organize the scan can fit easily into the room together with the system. Although the clinic is located in Paris exclusive right-bank 16th arron-dissement, its patients represent a cross-section of France’s 21st century multi-cultural population. Most of them are here for thorax and abdominal scans, although in the afternoon, a cardiologist

will swing by to supervise one of his twice-weekly, three-hour cardiac sessions.

The challenge of staying aheadThe World Health Organization places France at the top of its national health-care rankings. But, as anyone who even glances at the headlines can tell, the country is struggling with the same economic and budgetary pressures that plague the rest of Europe. Health remained a priority in the 2013 national budget, but the 2.7% increase in spending for the sector just barely outdistanced the 2012 inflation rate. The challenge both

for national leaders and hospital admin-istrators is the same: Find ways to maintain or even improve quality, while simultaneously keeping a lid on costs.The 180-bed Clinique Bizet is one of two branches of a hospital known as the Centre d’Imagerie de l’Ouest Parisien (West Parisian Imaging Center, or CIMOP). Although it is private, patients are referred from the public system, and fees are subject to the same controls that prevail elsewhere. With facilities squeezed into a sliver of prime Parisian real estate, the Clinique Bizet must also make the most of sometimes cramped quarters.

The team around Yves Martin-Bouyer, MD (left picture) and Philippe Durand at the Clinique Bizet in Paris found an ideal solution for their tight spatial conditions but high demands of CT imaging: the SOMATOM Definition Edge.


SOMATOM Definition Edge 64 slice

Scantime 4.0 s 13.53 s

kV-Setting 100 kV, 86 mAs

120 kV, 733 mAs

Scan length 147 mm

138 mm

DLP 217 mGy cm 1137 mGy cm

Dose 3.04 mSv 15.91 mSv

All of these factors came into play when Chief Radiologist Yves Martin-Bouyer, MD, needed to purchase a new scanner last year.CIMOP has a second, 140-bed branch – called Val d’Or – in the western Parisian suburb of Saint Cloud. The hospital has been working with Siemens equipment since 2000. It even mentions the relation-ship on its website. But that legacy provided no guarantees. Martin-Bouyer analyzed the pros and cons of machines made by all the major manufacturers. One was rejected outright because its equipment was simply too big for the space it was supposed to occupy.

Versatility and quality resultsMartin-Bouyer says that the Siemens SOMATOM® Definition Edge got the nod for three main reasons: ease of installa-tion, advanced technology, and top-notch software. In particular, the chief radiolo-gist liked the Siemens machine’s Stellar Detector, its high rotation speed (0.28 sec-onds), and fast pitch (up to 1.7), which is important for run-offs. “It is extremely versatile,” says the physician. “It can be used for oncology, vascular radiography, and examinations of the legs. You are able to get an image very quickly, and it is of superior quality. You have the feel-ing that the images are more reliable.”Cost was also a consideration. “I should also mention the financial factor,” Martin-Bouyer adds. “The prices were roughly the same. There was just a slight difference.” More than the purchase price, there was no need for reconstruction of the scan-ning room, so that it was possible to change the scanner only. In total a cost-sensitive high-end scanner that doesn’t need too much space.Consistently high quality images translate into fewer headaches for Clinique Bizet’s staff of four radiologists and 20 technicians, who together perform around 6,000 CT scans a year. “There are no discussions,” he says. “The results are very good.Philippe Durand, MD – head of the inter-ventional cardiac department at Saint Joseph Hospital in Paris – who oversees twice weekly sessions at the Clinique Bizet, seconds Martin-Bouyer’s verdict.

“There is not a single image that I cannot interpret,” he points out. “Before, there was at least one a day.”

Benefits to clinicians and patients alikeThanks to the Siemens SOMATOM Definition Edge, patients benefit from what Martin-Bouyer estimates to be an average of 30 to 40% reduction in radia-tion doses at his clinic, compared to the previous model. In coronary studies doses have even dropped from 950 DLP (dose length product) to 250.Examinations can also be performed more quickly. “The patient is on the machine for about 10 to 15 minutes,” estimates Martin-Bouyer. “It is very quick.” The chief radiologist reports that this does not generally translate into fitting more examinations into a workday. He says that the time devoted to the procedure itself is dwarfed by that required for pre-paring the patient for the test, as well as for the subsequent analysis. However, Durand reports boosting the number of examinations he can oversee during his three-hour slots at the Clinique Bizet, from between seven and eight to ten.

Getting to the heart of cardiac problemsThe scanner has proven especially effec-tive for cardiac examinations – around 550 cases per year at the Clinique Bizet. “The quality is the best you can imagine,” says Martin-Bouyer.“There is better resolution on the interior of a stent. You freeze the movement of the stent and the movement of the artery,” Durand adds. “You get great images, even with people who have rapid arrhythmias.” He says that the speed of the machine also helps patients who have trouble holding their breath for prolonged periods, which is often the case for peo-ple with heart conditions.CIMOP has enjoyed ISO 9001 certifica-tion on its quality management systems for nearly a decade. Now it is in the pro-cess of trying to attain a similar stamp of approval for its information security management system: namely ISO 27001. “This approval has become more likely, thanks to the SOMATOM Definition Edge,

1A

1B

1 Cardiac follow-up: SOMATOM Definition Edge delivers better image quality (Fig. 1A) almost 10 seconds faster and with a reduction in dose by over 12 mSv than previous 64-slice system (Fig. 1B).

with its superior compatibility. The machine can talk to other systems,” he notes. “Its data can be easily converted to work with other systems.”

Business

A former correspondent in South America for The Financial Times and Business Week, Bill Hinchberger is a Paris-based freelance writer. He has contributed to publications like The Lancet and Science, and reported for the Medical Education Network Canada.


Clinical Results Cardiovascular

Case 1 Coronary CTA with 80 kV: Improving Image Quality with Reduced Radiation and Contrast Medium Dose By Takehito Shizuka, MD*, Haruka Iwase, MD*, Hiroaki Kobayashi, MD*, Yae Matsuo, MD*, Saburou Yanagisawa, MD*, Nobuaki Fukuda, MD*, Akihiro Saitou, MD*, Shitoshi Hiroi, MD*, Toyoshi Sasaki, MD*, Chikashi Negishi, MD**, Youichi Satou, MD**

** Department of Cardiology, National Hospital Organization Takasaki General Medical Center, Japan** Diagnostic Imaging Center National Hospital Organization Takasaki General Medical Center, Japan

1 VRT images with different presets (Figs.1A and 1B) showed the CTO (arrows) and the aneurysm (dashed arrows) in the LAD. Neither calcified plaques nor thrombosis were seen in the aneurysm (Fig. 1C – MPR and Fig. 1D – MIP).

1A

1C

1B

1D

HISTORY

An 84-year-old female patient, with a history of hypertension and dyslipidemia, was hospitalized due to heart failure. Cardiac enzyme tests were normal. After an improvement of her heart failure, the first coronary CTA was performed. This revealed an aneurysm and a chronic total occlusion (CTO) of the left anterior des-cending artery (LAD) and a 75% stenosis of the right coronary artery (RCA) which was then treated with a stent. A second coronary CTA was performed to evaluate the characteristics of the CTO after the intervention.

DIAGNOSIS

An aneurysm located directly in front of the diagonal and the septal branches, as well as the CTO (Figs. 1A and 1B), could be clearly visualized in the LAD. Neither calcified plaques nor thrombosis were seen in the aneurysm (Figs. 1C and 1D). A stent shown in the proximal RCA was patent (Fig. 3A). The distal branches of the RCA were well developed supposedly to compensate the limited blood supply of the occluded LAD. A few small calcified plaques were present in the proximal circumflex artery (Cx, Fig. 3B).


COMMENTS

To achieve the optimal CT image quality with the lowest possible dose, various CT techniques have been established. In the newly developed Stellar Detector, the photodiode and the analog-to-digital converters (ADCs) were combined in single application-specific integrated cir-cuit (ASICs). This therefore reduces the path of the analog signal and decreases the electronic noise which in turn directly enhances the image quality. In this case, SAFIRE as a raw data-based iterative recon-struction technique, Flash Cardio Spiral provided by Dual Source CT, CARE kV, and CARE Dose4D were all additionally applied to minimize the dose to 0.38 mSv while maintaining the image quality. The 80 kV setting selected by CARE kV remarkably enhanced the contrast although only 42 mL (including test bolus injection) contrast medium were used.

2 An angiographic image (Fig. 2A) and a VRT image (Fig. 2B) demonstrated both left and right arteries.

3 A patent stent in the RCA (Fig. 3A) and few small calcified plaques could be revealed with curved MPRs (Fig. 3B).

2A

3A

2B

3B

ExAMINATION PROTOCOl

Scanner SOMATOM Definition Flash

Scan area Heart Pitch 3.4

Heart rate 56 bpm Slice collimation 128 x 0.6 mm

Scan length 111 mm Slice width 0.75 mm

Scan direction Cranio-caudal Spatial resolution 0.3 mm

Scan time 0.2 s Reconstruction increment

0.4 mm

Tube voltage 80 kV with CARE kV Kernel I36f

Effective mAs 316 mAs SAFIRE SAFIRE

Dose modulation CARE Dose4D Contrast

CTDIvol 1.46 mGy Volume 42 mL (including test bolus)

DLP 27.1 mGy cm Flow rate 3.5 mL/s

Effective dose 0.38 mSv Start delay Test Bolus Tracking

Rotation time 0.28 s

In clinical practice, the use of SAFIRE may reduce CT patient dose depending on the clinical task, patient size, anatomical location, and clinical practice. A consultation with a radiologist and a physicist should be made to determine the appropriate dose to obtain diagnostic image quality for the particular clinical task.



Case 2 70 kV CT Pulmonary Angiography in an Adult Patient with a Dose of < 1 mSv and PA Attenuation of > 1,000 HUBy Ralf W. Bauer, MD, Firas Al-Butmeh, MD, Boris Schulz, MD, Thomas J. Vogl, MD, J. Matthias Kerl, MD

Department of Diagnostic and Interventional Radiology, Goethe University Frankfurt, Germany

HISTORY

A 31-year-old female patient underwent a CT pulmonary angiography (CTPA) for a clinically suspected pulmonary embolism (PE). CTPA was conducted on a SOMATOM Definition AS (64-slice con-figuration) with a novel 70 kV protocol.

DIAGNOSIS

The patient conforms to a normal body habitus (173 cm, 65 kg, BMI 21.7 kg/m²). The 70 kV protocol, combined with SAFIRE, resulted in a very low dose expo-sure of only 0.77 mSv (DLP 55 mGy cm x 0.014 mSv/mGy cm) for an entire chest scan. Due to the low-energy X-ray spec-trum emitted at 70 kV, the intravascular


Scanner SOMATOM Definition AS (64-slice configuration)

Scan area Chest Rotation time 0.5 s

Scan length 277.5 mm Pitch 1.2

Scan direction Cranio-caudal Slice collimation 64 x 0.6 mm

Scan time 6.02 s Slice width 1.0 mm

Tube voltage 70 kV Reconstruction increment 0.5 mm

Tube current 141 eff. mAs Reconstruction kernel I26f SAFIRE 3


CTDIvol 1.85 mGy Volume 60 mL

DLP 55 mGy cm Flow rate 4 mL/s

Effective dose 0.77 mSv Start delay 5 s

attenuation in the pulmonary arteries exceeded 1,000 HU in the central and 850 HU in the segmental branches, although only 60 mL of iodinated contrast material were administered (350 mg Iodine/mL). This resulted in an overall excellent image quality which allowed the reliable exclusion of a PE.

COMMENTS

Due to unspecific symptoms, many patients are referred for CTPA to exclude a PE with negative results. Low true positive rates are still a common problem, although scores, e.g. the Wells score, are adapted increasingly to estimate the

In clinical practice, the use of SAFIRE may reduce CT patient dose depending on the clinical task, patient size, anatomical location, and clinical practice. A consultation with a radiologist and a physicist should be made to determine the appropriate dose to obtain diagnostic image quality for the particular clinical task. The following test method was used to determine a 54 to 60% dose reduction when using the SAFIRE reconstruction software. Noise, CT numbers, homo-geneity, low-contrast resolution and high contrast resolution were assessed in a Gammex 438 phantom. Low dose data reconstructed with SAFIRE showed the same image quality compared to full dose data based on this test. Data on file.

pre-test likelihood of a PE. Therefore, it is essential to reduce radiation exposure in this patient group to a minimum. The novel 70 kV option, combined with model-based iterative reconstruction (SAFIRE), helps to achieve unprecedented low dose values with high image quality, not only in children, but also in adults with normal body habitus. The low-energy X-ray spectrum results in extremely high vascular attenuation with common high-iodine content contrast material. This bears potential for the use of low-iodine contrast media and an overall reduced iodine load. This could be bene-ficial for high-risk patients regarding contrast-induced nephropathy.


1–6 Excellent image quality in a normal sized female patient (Fig. 1). The extreme vascular attenuation requires a wider win-dow (w 1700, c 250) to reduce the signal from iodine in the pulmonary arteries (Fig. 2); attenuation of more than 1000 HU in the pulmonary trunk (Fig. 3). Attenu-ation of almost 900 HU in the segmental pulmonary arteries was achieved with only 60 mL of iodinated contrast material with an iodine concentra-tion of 350 mg/mL (Fig. 4). MIP (Fig. 5); VRT (Fig. 6) images showed the brightly enhanced pulmonary arteries including the peripherals.

5 6

3 4

1 2

Cardiovascular Clinical Results



Case 3 Dual Source CT: Assessment of Hypoplastic Arch Associated with Ductus ArteriosusBy Torel Ogur, MD, Patrick T. Norton, MD, Klaus D. Hagspiel, MD

Department of Radiology and Medical Imaging, University of Virginia, USA

HISTORY

A 13-day-old male baby, with numerous congenital abnormalities including left lateral displacement of the left nipple and umbilicus, digital abnormalities that were attributable to amniotic bands, displaced anus and spinal dysraphism was referred for CT Angiography (CTA) of the chest for detailed evaluation of an aortic arch anomaly.

1 Two images at the level of the aortic arch demonstrate the decrease in image noise and increase in signal to noise ratio when using SAFIRE (Fig. 1A) versus filtered back projection (Fig. 1B).

DIAGNOSIS

The volume rendered images, using the SAFIRE reconstructed images, showed a hypoplastic arch with a patent ductus arteriosus (Figs. 2). The ascending aorta measured 7 mm in diameter and the aortic arch demonstrated diffuse narrow-ing down to between 2.4 and 2.6 mm. This was most pronounced in the pre-ductal segment. The left vertebral artery

1A 1B

originated directly from the aortic arch. The ductus arteriosus was patent and measured 4.5 mm. The descending thoracic aorta measured 5.3 mm distal to the patent ductus arteriosus.




Scan area Thorax

Scan length 75 mm

Scan direction Cranio-caudal

Scan time 1.2 s

Tube voltage 80 kV

Tube current 32 eff. mAs

Dose modulation CARE Dose4D

CTDIvol 0.51 mGy

DLP 4.2 mGy cm

Effective dose 0.37 mSv


Pitch 0.6

Slice collimation 128 x 0.6 mm

Slice width 0.6 mm

Reconstruction increment

0.4 mm

Reconstruction kernel

I30f (SAFIRE)

Contrast

Volume 4 mL

Flow rate Hand injection iv in left saphenous vein at approx. 0.5 mL/s

Start delay 2 s

2 Two volume rendered images using the SAFIRE reconstructed images show a hypoplastic arch (Figs. 2, arrow) with patent ductus arteriosus (Fig, 2B, dashed arrow).

COMMENTS

The scan was performed employing the X-CARE scan mode, CARE Dose4D and CARE kV on a SOMATOM Definition Flash scanner. Reference mAs was set at 125, reference kV at 120 kV, and the CARE kV slider set to 7. CARE kV automatically selected 80 kV and an average effective mAs of 32. Radiation dose could further be reduced by using SAFIRE level 3 iterative reconstructions, resulting in an extremely low age adapted effective dose of 0.37 mSv for this fully diagnostic CTA scan of the chest.Pediatric patients with congenital abnormalities often require multiple imaging exams over their lifetime. This makes it critical to keep cumulative radiation dose as low as possible while maintaining diagnostic accuracy. In addition to being fully diag-nostic, the rapid acquisition time of only 1.2 seconds obviated the need for breath-holding and sedation. A comparison of two images (Figs. 1A and 1B) at the level of the aortic arch reconstructed with both filtered back projection and iterative reconstruction, demonstrated the decrease in image noise and increase in signal to noise ratio achieved with SAFIRE.

2A

2B

In clinical practice, the use of SAFIRE may reduce CT patient dose depending on the clinical task, patient size, anatomical location, and clinical practice. A consultation with a radiologist and a physicist should be made to determine the appropriate dose to obtain diagnostic image quality for the particular clinical task. The following test method was used to determine a 54 to 60% dose reduction when using the SAFIRE reconstruction software. Noise, CT numbers, homogeneity, low-contrast resolution and high contrast resolution were assessed in a Gammex 438 phantom. Low dose data reconstructed with SAFIRE showed the same image quality compared to full dose data based on this test. Data on file.




Case 4 Cardiac CT in a 5-Month-Old Baby with VACTERL Syndrome after Cardiac SurgeryBy Torel Ogur, MD, Patrick T. Norton, MD, Klaus D. Hagspiel, MD

Department of Radiology and Medical Imaging, University of Virginia, USA

HISTORYA 5-month-old baby boy with a history of double outlet right ventricle (DORV) with atrial septal defect (ASD), ventricular septal defect (VSD), patent foramen ovale (PFO) and VACTERL syndrome (unilateral renal agenesis, syndactyly, congenital hemivertebrae) was referred for cardiac CT. He underwent surgical repair with an ASD and VSD patch and PFO ligation at ten weeks of age. He was readmitted due to atrial tachycardia and worsening pulmonary hypertension. Cardiac cathe-terization revealed systemic pulmonary artery (PA) pressures and near atretic left pulmonary veins. The cardiac surgeon requested the CT for a detailed evaluation of the pulmonary veins prior to possible surgical repair.

DIAGNOSIS

The study was performed using the Flash mode and 80 kV. SAFIRE was used to allow further reduction of the radiation dose. The scan demonstrated four sepa-rate pulmonary veins, all of which drained into the left atrium. The right inferior pulmonary vein was normal, whereas the right superior vein had a severe ostial stenosis (Figs. 1A and 1B). The left supe-rior pulmonary vein also had a severe ostial stenosis and the left inferior pul-monary vein was occluded at the ostium (Figs. 1C and 1D). There was no evidence of an ASD or VSD, and the PFO was suc-cessfully ligated. There was also a left aortic arch with aberrant right subclavian artery (Fig. 2). The left main coronary artery originated abnormally from the

1 Axial Minimum Intensity Projection (MIP) images demonstrate the severely stenotic ostium of the right superior (Fig. 1A, arrow) and the normal right inferior pulmonary vein (Fig. 1B, arrow). The left superior vein has a high grade ostial stenosis (Fig. 1C, arrow) and the left inferior pulmonary vein is occluded (Fig. 1D, arrow).

1A

1C

1B

1D


2 A VRT image shows the aberrant right subclavian artery (arrow). 3 A VRT image shows the right upper lobe bronchus (arrow) originating from the trachea, a so-called pig bronchus.

left aspect of the non-coronary sinus (Fig. 4). The right upper lobe bronchus originated directly from the right aspect of the trachea, a so-called pig bronchus (Fig. 3).

COMMENTS

Children with congenital heart disease often require repeated cardiac imaging studies for follow-up. Even though echo-cardiography is the most important diag-nostic modality, CT can be necessary in selected cases. Therefore, it is of the utmost importance to keep the radiation dose as low as possible. The use of the Flash cardiac mode combined with a low kV setting, allowed the study to be performed with very low dose. Newer reconstruction techniques, other than the classical filtered back projection algo-rithm, allow further reduction of dose while maintaining or even improving the image quality. Iterative reconstruction (SAFIRE) was used in this case, demon-strating the pulmonary venous and over-all cardiac and aortocoronary anatomy in high quality with an estimated age-adapted effective radiation dose of only 1.88 mSv.

2

4 An axial subvolume MIP image demonstrates the origin of the left main coronary artery (arrow) from the left aspect of the non-coronary sinus.

4

3



Scan mode Flash mode

Scan area Heart

Scan length 87 mm


Scan time 0.2 s

Tube voltage 80 kV



CTDIvol 1.32 mGy

DLP 21 mGy cm



Pitch 3.0


Slice width 0.6 mm


0.6 mm


I26 / 41f (SAFIRE)

Contrast 350 mg/ccm diluted with saline

Volume 7 mL diluted to 10 mL

Flow rate 1 mL/s

Start delay Bolus tracking


In clinical practice, the use of SAFIRE may reduce CT patient dose depending on the clinical task, patient size, anatomical location, and clinical practice. A consulta-tion with a radiologist and a physicist should be made to determine the appropriate dose to obtain diagnostic image quality for the particular clinical task. The follow-ing test method was used to determine a 54 to 60% dose reduction when using the SAFIRE reconstruction software. Noise, CT numbers, homogeneity, low- contrast resolution and high contrast resolution were assessed in a Gammex 438 phantom. Low dose data reconstructed with SAFIRE showed the same image quality compared to full dose data based on this test. Data on file.



Case 5 Evaluation of Femoral Artery Pseudoaneurysms with Arteriovenous Fistula using CTA Runoff ScanningBy Hong liang Zhao, MD

Department of Radiology, Xijing Hospital, Xian, P.R. China

HISTORY

A 16-year-old male patient, with a known history of trauma, developed a tender pulsatile mass in his left thigh. A CT Angiography (CTA) runoff was ordered to evaluate detailed vascular structures.

DIAGNOSIS

Two saccular pseudoaneurysms were found in the left upper-mid thigh (Fig. 1). Both aneurysms breached into the left superficial femoral artery (Fig. 2). Tumor-like venous structures developed locally, due to a fistula connecting the aneurysms and the femoral vein (Fig. 2). Most of the veins drained into the great saphenous vein, resulting in an ectatic state of the vein. The left femoral artery was signifi-cantly dilated. There were neither signs of mural thrombosis nor of wall thicken-ing of the aneurysm. The vascular struc-tures in the right leg appeared to be normal.



Scan area CTA Runoff Pitch 0.9

Scan length 1,102 mm Slice collimation 128 x 0.6 mm

Scan direction Cranio-caudal Slice width 1 mm

Scan time 16 s Spatial Resolution 0.33 mm


Tube current 190 eff. mAs Reconstruction kernel B26f


CTDIvol 3.72 mGy Volume 70 mL

DLP 419 mGy cm Flow rate 3.5 mL/s

Effective Dose 1.82 mSv Start delay 21 s

Rotation time 0.5 s

COMMENTS

Pseudoaneurysms are common vascular abnormalities caused by the disruption of the vessel wall. A pseudoaneurysm with an arteriovenous fistula is rare. Prompt diagnosis and treatment are necessary to avoid the morbidity and mortality asso-ciated with hemorrhage and rupture. Low dose CTA is valuable in the imaging workup and may help enable a quick diagnosis.


1 An overview of the CTA runoff. 3 The vascular structures can be shown with VRT images using different presets.

2 Thin slab VRT image shows the breach of the aneurysm (arrow) and the fistula to the femoral vein (dashed arrow).

1 2

3A 3B



Case 6 Free-breathing Coronary CTA with Double Flash Spiral ProtocolBy Man Ching So, MD*, Chi Ming Wong, MD*, Wai leng Chin**

** Sir Run Run Shaw Heart & Diagnostic Center, St. Teresa’s Hospital, Kowloon, Hong Kong SAR, China** Siemens Healthcare, Singapore

1 Double Flash Spiral scan with a single contrast injection in the same patient scanned with free-breathing. VRT (Fig. 1A) and curved MPR (Fig. 1C) images of 1st Flash Spiral scan which was free from breathing artifact and 2nd Flash Spiral scan (Figs. 1B and 1D) with one slight breathing artifact (arrows) in the distal LAD.

1C 1D

1B1A


HISTORY

An 80-year-old female patient, with known hypertension, obesity, supra-ven-tricular ectopic, and supra-ventricular tachycardia, presented herself due to recent onset of chest discomfort. Coro-nary CTA was performed to exclude the presence of ischemic heart disease. Upon arrival, the patient had a heart rate of 61 beats per minute and could not hold her breath. Therefore the examination was conducted using the double Flash Spiral (prospectively ECG-triggered high-pitch mode) protocol under free-breathing. Two Flash Spiral scans were consecutively performed with a single bolus of intravenous contrast medium.

DIAGNOSIS

The patient’s calcium score was 1,788 and all 3 arteries showed pathological changes. A severe stenosis was demon-strated in the mid left anterior descend-ing artery (LAD) as well as a moderate stenosis in the proximal left circumflex (LCX) artery. There were mild stenoses in the left main, the proximal left LAD, the first diagonal artery, the right coronary artery and the first obtuse marginal artery. The posterior descending, postero-lateral and distal left anterior descending arteries were normal. Conventional angiography confirmed severe stenoses in the mid

2 The stenosis correlated with conventional angiogram.

2



Scan area Mid-pulmonary arteries to diaphragm

Pitch 3.4

Scan length 116 mm Slice collimation 128 x 0.6 mm

Scan direction Cranio-caudal Slice width 0.75 mm

Scan time 0.39 s Spatial Resolution 0.33 mm


Tube current 370 mAs Reconstruction kernel B26f & B46f

Dose modulation No Contrast 400 mg/mL

CTDIvol 3.58 + 3.59 mGy Volume 60 mL

DLP 117.86 mGy cm Flow rate 5 mL/s

Effective dose 1.65 mSv Start delay Test bolus + 2 sec

Rotation time 0.28 sec

LAD and proximal LCX. Pericutaneous coronary intervention with implantation of a drug eluting stent in the mid LAD and LCX, after rotational atherectomy under intravascular ultrasound guidance, was successful.

COMMENTS

This case demonstrated that coronary CTA performed in patients who are unable to hold their breath with the double Flash Spiral protocol allows the diagnosis of coronary artery stenoses and can potentially simplify the planning of a coronary interventional procedure.



Clinical Results Oncology

Case 7 Squamous Cell Carcinoma of the Head and Neck: Volume Perfusion CTBy Timothy J. Amrhein, MD, Zoran Rumboldt, MD, PhD

Department of Radiology and Radiological Sciences, Medical University of South Carolina, Charleston, SC, USA

4.5 cm posterolateral to the primary mass and would not typically have been included with standard neck perfusion CT protocols. Mean BF and CP values within the primary mass were 144.6 (mL/100g/min) and 38.7 (mL/100g/min), respec-

HISTORYA 54-year-old male with a three-month history of a tender right neck mass associated with right-sided headaches, epistaxis, otalgia, diplopia, and pares-thesias of the right face and tongue, was referred to the otolaryngology for further evaluation. The patient reported fevers, night sweats and weight loss. A fine needle aspirate of the dominant right neck mass yielded a preliminary diagnosis of squamous cell carcinoma. The patient was then referred to the radiology for diagnostic imaging.

DIAGNOSIS

An initial pre-treatment contrast enhanced neck-CT (CENCT) demonstrated an avidly enhancing heterogeneous 4.2 x 2.6 x 5.7 cm mass, arising from the right nasopharynx with lateral extension into the right masticator space and supe-rior extension into the right foramen ovale and cavernous sinus (Figs. 1A and 1B). Additionally, there was an enlarged avidly enhancing right level IIB lymph node with central hypoattenuation sug-gestive of necrosis (Figs. 1C and 1D). The patient then underwent Volume Perfusion CT (VPCT) of the neck to further charac-terize the underlying pathology. This VPCT demonstrated elevated capillary perme-ability (CP), blood volume (BV), and blood flow (BF) within the primary mass rela-tive to normal adjacent tissues (Fig. 2A). Similar characteristics were identified within the viable periphery of the cen-trally necrotic right level 2B lymph node (Fig. 2B). Of note, this lymph node was located approximately 5 cm inferior and

tively. These elevated values predicted a good treatment response to chemother-apy and radiation therapy. Similar values were present in the nodal metastasis (111.8 mL/100g/min and 29.7 mL/100g/min respectively).

1 Initial pretreatment CENCT. Axial image demonstrated avidly enhancing heterogeneous mass arising from the right nasopharynx with lateral extension into the right masticator space (Fig. 1A). Coronal image demonstrated superior extension of the primary mass into the foramen ovale and cavernous sinus (Fig. 1B). Axial image demonstrated a markedly enlarged and peri-pherally enhancing right level IIB lymph node concerning metastatic involvement (Fig. 1C). Coronal image redemonstrated the enlarged concerning right level IIB lymph node (Fig. 1D).

1A

1C 1D

1B


2 Neck VPCT: CP, BV, BF and reduced MTT within the primary mass were elevated (Fig. 2A). Similar perfusion characteristics within a right level IIB lymph node concerning metastatic involvement could be detected (Fig. 2B).

3 Post treatment CENCT. Primary right nasopharyngeal mass (Fig. 3A) and right level IIB lymph node were resolved (Fig. 3B).


Scanner SOMATOM

Definition AS+

Scan modeVolume Perfusion Protocol using Adaptive 4D Spiral

Scan area Neck

Scan length 130 mm


Scan time 49 s

Tube voltage 80 kV



CTDIvol 128 mGy

DLP 1875 mGy cm

Rotation time 0.3 s


Slice width 3 mm


2 mm


B20f

Contrast

Volume40 mL contrast + 50 saline

Flow rate 4 mL/s

Start delay No delay

3A

2A

3B

The patient underwent standard chemotherapy and radiation therapy and returned for a follow up CENCT four months after the initial scan. This demonstrated a near complete to com-plete response with macroscopic resolu-tion of the primary neoplasm and nodal disease (Fig. 3). There was no evidence of residual or recurrent disease over the following 3 months.

COMMENTS

VPCT offers dynamic perfusion analysis of the entire neck allowing for character-ization of both the primary neoplasm and areas of nodal involvement. Standard neck perfusion CT is unable to cover the entire neck volume precluding the concomitant acquisition of perfusion information in areas of nodal metastatic disease. Changes in functional parameters acquired with VPCT may allow for prediction of treat-ment response before and during therapy.

2B


Clinical Results Oncology

Case 8 Diagnosis of Rectal Tumor using SOMATOM PerspectiveBy Zheng, Tiesheng, MD, Sun, Hongtu, MD, Wu, Yuzhang, MD

Department of Radiology, Panshi City Hospital, Jilin, P. R. China

HISTORYA 62-year-old female patient, with a known diagnosis of “rectal tumor”, presented herself for further evaluation before treatment.

DIAGNOSIS

CT images showed a cauliflower-like, broad-based soft tissue mass located on the left-posterior wall of the rectum (Figs. 1 to 3). It measured 25 x 22 mm and was causing luminal narrowing. There were no signs of wall thickening nor of infiltration of the peri-rectal fat. The enhancement of the mass was mild and homogeneous. A regular shaped, hypo-dense lesion (Fig. 4) was revealed in the

left hepatic lobe, measuring 13 x 10 mm in size and with 15 HU CT value. After intravenous contrast injection, no enhancement was present suggesting a cyst. Neither enlarged lymph nodes nor ascites were found. All other abdominal and pelvic organs appeared to be normal.A rectalscopic examination resulted in a benign rectal tumor. The patient was scheduled for a rectoscopical tumor resec-tion.

COMMENTS

Although rectoscopy is accurate in the detection of rectal tumors, it does not allow the evaluation of extra-rectal

1 Coronal (Fig. 1A) and sagittal (Fig. 1C) MPR and VRT (Fig, 1B) images show the rectal tumor that caused luminal narrowing (arrows). The peri-rectal fat tissues are not infiltrated (dashed arrows).

1A 1B 1C

diseases. CT is valuable in the preopera-tive assessment and staging in assumed cases of cancer. Rapid advances in CT technology have improved the accuracy and usefulness of computer imaging. In our department, we experience the great advancement from 6-slice to 128-slice in the daily routine examina-tions. It allows a longer scan range within a shorter scan time and with a slice width as thin as 0.6 mm. The fast scanning speed also reduces motion artifacts. Furthermore, the newly devel-oped syngo.via workstation allows efficient reading and decreases the post-processing workload.


2 syngo.via helps to speed up reading and facilitates creation of findings.

3A

4A

4B


Scanner SOMATOM Perspective

Scan area Abdomen / pelvis Rotation time 0.6 s

Scan mode Arterial / venous phase Pitch 0.6

Scan length 518 mm Slice collimation 64 x 0.6 mm

Scan direction Cranio-caudal Slice width 1 / 7 mm

Scan time 13 s Reconstruction increment

0.7 / 7 mm

Tube voltage 110 / 130 kV Reconstruction kernel B30s

Tube current 86 / 74 mAs Contrast Iopromide 370

Dose modulation CARE Dose4D Volume 80 mL

CTDIvol 6.36 / 8.15 mGy Flow rate 3 mL/s

DLP 374.27 / 491.44 mGy cm Start delay Bolus tracking

Effective dose 5.6 / 7.4 mSv

4 Axial images of arterial (Fig. 4A) and venous (Fig. 4B) phases reveal the non-enhanced hepatic lesion (arrows).

3 Axial images of arterial (Fig. 3A) and venous (Fig. 3B) phases present mild and homogenous enhancement of the tumor (arrows).

2

3B


Clinical Results Neurology

Case 9 Dose Reduction in Head CT Examination using SAFIREBy Fabio Onuki Castro, MD, Juliana Mancini Ruthes, MD, Carlos Martinelli, MD, Caroline Bastida de Paula*, Vinicius Zim Henrique*

Department of Radiology, Hospital do Coração, São Paulo Brazil *Siemens Healthcare, Brazil

HISTORY

A 90-year-old male patient had suffered from an extensive ischemic stroke in the irrigation territory of the middle-right cerebral artery. This had caused significant compression on noble brain structures. He underwent a decompressive craniec-tomy. A CT examination was ordered for follow-up.

DIAGNOSIS

CT images showed large areas of brain loss (encephalomalacia/gliosis) involving the right temporal region. This was characterized by hypodense cortical/ subcortical areas as seen in CT and was associated with the accentuation of the brain grooves and fissures. A similar area involving the frontal cortical gyri, adja-cent to the upper left area of surgical decompression (craniotomy), could also be seen.

COMMENTS

A comparative analysis was performed on the images, reconstructed with and without SAFIRE. Not only would SAFIRE allow the dose to be reduced, the image quality was also significantly improved. Even though, in this special case, a fast scan (pitch 1.4) was performed to prevent artifacts that might had been caused by

the uncontrollable motion of the patient. The improvements were demonstrated by the higher definition around the edges and by the improved signal-to-noise ratio in the images.The efficiency of the SAFIRE technology may contribute to diagnostic accuracy.



Scan area Head

Scan length 162 mm

Scan direction Caudo-cranial

Scan time 3 s

Tube voltage 100 kV

Tube current 380 mAs


CTDIvol 36.62 mGy

DLP 744 mGy cm


Rotation time 1 s

Pitch 1.4


Slice width 1 mm


0.7 mm

Reconstruction kernel H30s w/o SAFIREJ30s with SAFIRE

In clinical practice, the use of IRIS may reduce CT patient dose depending on the clinical task, patient size, anatomical location, and clinical practice. A consultation with a radiologist and a physicist should be made to determine the appropriate dose to obtain diagnostic image quality for the particular clinical task.


Neurology Clinical Results

2A

1A1–4 The figures show four different slices (Figs. 1 to 4) with and without SAFIRE (A – without; B – with SAFIRE). The “B” images show a great noise reduction and a better differentiation between healthy and damaged brain tissue. There is also a considerable sharpening on the edges, especially in the craniotomy area. (For all images, window settings = 90/45, slice width = 3 mm). Courtesy of Hospital do Coração, São Paulo, Brazil.

4B4A

2B

1B

3B3A


Science

Finding the Right Dose with the Right ToolsBelgian radiologist Tom Mulkens, MD, PhD, from the Heilig Hartziekenhuis in Lier is a CT specialist with particular interest in radiation dose. His long- time engagement shows that reducing the dose in CT exams is not only a question of good practice, but also of the right tools and continuous efforts to preserve diagnostic image quality.

By Irène Dietschi

Some participants at the European congress of radiology (ECR) 2013 were surprised when Tom Mulkens, a tall and silver-haired radiologist from Belgium, commented on the presentations of a French and Spanish colleagues. The CT images projected on the over-sized screen of the conference room in Vienna were as clear-cut as any clinician could wish for an accurate diagnosis. Yet, it wasn’t the image quality the Belgian specialist dared question, but the accompanying dose values. Both presentations showed mean DLP values of 800 and 900 mGy cm for standard head CT, for example. Tom Mulkens criticized those values as out-dated. At his own hospital in Belgium, standard head CT is performed at an average DLP of 340 mGy cm, an average CTDI of 20 mGy and a mean effective dose of 0.85 mSv. The scanners used are SOMATOM® Emotion 16 and SOMATOM Definition AS+ by Siemens.

Tom Mulkens, radiologist at the Heilig Hartziekenhuis in Lier, is a well-known CT specialist in his country. “Dose reduc-tion in CT has been my very special inter-est for 15 years; it has almost become a hobby,” the 50-year-old doctor says. In Belgium he has visited nearly every radi-ology department to generate awareness of this important issue. His know-how in dose modulation and the scan protocols of his department, where around 14,000 to 15,000 CT scans are performed every year, are in high demand among his col-leagues. “Good images and dose reduction don’t necessarily compete,” he says. “CT technology has advanced so much in the last ten to fifteen years that radiation can be reduced substantially without impair-ing the quality of the image.”Tom Mulkens has been adamant about this topic ever since in 2001 articles started to come out trying to connect CT scans with possible future cancers. “Although

these numbers were rough estimates based on a purely theoretical extrapolation of the linear non-threshold model to low dose values, the news of these publica-tions shocked the radiology community,” says Tom Mulkens. For him personally the papers had an even greater effect: He started his research on dose optimi-zation in CT exams.In a 2005 study, he and his team exam-ined the effect of an automatic exposure control mechanism in CT, thereby reduc-ing radiation doses between 20 and 68%. [1] A study on children suffering from sinusitis, published around the same time, was equally successful. [2] Mulkens et al. were able to lower the effective dose to a level comparable to that used for stan-dard radiography, with resulting CT scans that were still of diagnostic image qual-ity. Active dose management shows that between 2006 and 2012 his department accomplished a cut in the mean radiation

Tom Mulkens, MD, PhD (left picture) and his team, Heilig Hartziekenhuis in Lier, Belgium has a special interest for years: Reduction of radiation dose.


Science

dose between 50 and 68% for adults (Table 1) and children, depending on the CT examination, e.g. from a DLP of 1,000 to 327 mGy cm for head scans.In 2012 two new Siemens CT scanners were installed in the Heilig Hartzieken-huis, both with Right Dose Technology, including iterative reconstruction possi-bilities: IRIS for the SOMATOM Emotion 16 and SAFIRE for the SOMATOM Definition AS+. This new function made the biggest difference so far. “Thanks to SAFIRE we were able to cut the doses roughly by half.” Even in difficult conditions, Tom Mulkens and his team now manage good values. He mentions the case of a very obese patient who was referred to radi-ology with diverticulitis, requiring a scan of the abdomen. “In a standard protocol, with a patient being very obese, the Contrast-to-Noise ratio (CNR) would have been much lower, but we were able to increase it by use of iterative reconstruc-tion and by choosing a low tube voltage with the help of CARE kV,” the doctor says (Fig.1).The improvements become most apparent in pediatric CT, an area where the need for dose reduction is most obvious because

children, depending on their age, are five to eight times more sensitive to radiation than adults. Tom Mulkens shows that his data for pediatric CT in 2012 were now way below the reference values prescribed by the Belgian authorities Federal agency for nuclear control (FANC) in 2010. The CT of the head, for example, in Mulkens’ department is now performed with a CTDI of 11 mGy (children below 12 months)

to 20 mGy (adults), whereas the official Belgian numbers for this examination range from a CTDI of 35 to 50 mGy.Mulkens recounts two recent clinical examples to illustrate the differences: A newborn baby who had a traumatic delivery after very long labor with vacuum extraction of the head in a nearby univer-sity hospital received a CT scan of the head (Fig. 2) the same day. The images showed

1 CT abdomen in a very obese 65-year-old-man (BMI > 35) with acute colon sigmoid diverticulitis (arrows) at 100 kV. CARE kV and 185 mAs was used, which gives a CTDIvol of 7.3 mGy and DLP of 348 mGy cm of the whole exam. That corresponds to a calculated effective dose of 5.2 mSv.

1A 1B

EU3 France4 Belgium5 Belgium5 HH lIER HH lIER HH lIER HH lIER

year 1999 2004 2007 2007 2006 2009 2011 2012

percentile 75 % 75 % 75 % 25 % mean value

mean value

mean value

mean value

CT HEAD 1050 1050 1020 740 1000 850 600 327

CT THORAx 780 500 400 240 220 240 225 115

CT ABDOMEN 780 650 830 415 400 410 350 212

CT l - SPINE n.a. n.a. 870 475 375 525 500 325

CT SINUS n.a. n.a. 150 70 60 65 60 33

Table 1: Evolution of local dose values as dose length product (DlP) in mGy cm

Evolution of local dose values (DLP, mGy cm) in CT in adults, Heilig Hartziekehuis Hospital, Lier in comparison with recommended national and European diagnostic reference level (DRL) values, 2006-2012.

actual dose valuesreference dose values


2 Newborn male baby with traumatic head delivery with vacuum extraction at nearby university hospital. CT of the head the same day shows small hemorrhagic brain lesions (arrow) and overlapping of the skull bones (Fig. 2A). Control CT of the head at the Heilig Hartziekehuis showed complete recovery with no residual brain lesions or injury four months later (Fig. 2C). Scan para-meters showed dose reduc-tion of 50% after use of SAFIRE, compared with initial CT scan at birth. 2D CTDIvol value is based on a 16 cm phantom.

some small hemorrhagic brain lesions (arrow) and overlapping skull bones. The CT dose parameters were CTDIvol of 20.12 mGy, DLP of 322 mGy cm and a calculated effective dose of 3.2 mSv. “A control CT scan at our own hospital four months later showed complete recovery of the hemorrhagic brain lesions and bone lesions,” Mulkens says. In this case the dose level was now 50% lower, with an effective dose of 1.6 mSv and comparable diagnostic image quality (Fig. 2).Another case was that of a newborn admitted to his department with respi-ratory distress after a very fast delivery. The X-rays the radiologists made of the thorax did not show clearly enough whether the baby was suffering from pneumothorax or pneumomediastinum-air formation between the heart, lungs and the chest wall. “I suggested to do a CT, which confirmed the presence of

a bilateral pneumothorax,” Mulkens recounts (Fig. 3). The CT was performed at a dose level not higher than in a stan-dard radiographic exam. The baby was fine and recovered from the pneumo-thorax without a specific therapy.X-ray dose in CT will remain a key issue for the radiology team in Lier. Growing experience and increasing medical tech-nology will be important companions for them to maintain their pioneer position in dose reduction.

2A 2B 2C

3 Male newborn with respiratory distress after very fast delivery. Standard radiography, which was repeated several times in the first few days, showed disturbing image of bilate-ral air collections, indicat-ing bilateral pneumothorax (Fig. 3A, arrows). CT exam (Fig. 3B) of the thorax on day 5 with comparable dose (effective dose of 0.14 mSv) to thorax radiography con-firmed the diagnosis of bilateral pneumothorax.

3A 3B

Irène Dietschi is an award-winning Swiss science and medical writer. She writes for the public media, such as the Neue Zürcher Zeitung and has published several books.

Scan kV mAs /ref. CTDIvol mGy

DlP mGy cm

TI s

cSl mm

Patient Position H-SP

Topogram 1 80 35 mA 2 2.7 0.6

Non contrast head scan

2 100 101 / 250 8.83 147 1.0 0.6

2D

In clinical practice, the use of SAFIRE may reduce CT patient dose depending on the clinical task, patient size, anatomical location, and clinical practice. A consultation with a radiologist and a physicist should be made to determine the appropriate dose to obtain diagnostic image quality for the particular clinical task. The follow-ing test method was used to determine a 54 to 60% dose reduction when using the SAFIRE reconstruction software. Noise, CT numbers, homogeneity, low-contrast resolution and high contrast resolution were assessed in a Gammex 438 phantom. Low-dose data reconstructed with SAFIRE showed the same image quality compared to full-dose data based on this test. Data on file.


References[1] Mulkens TH et al., Radiology.

2005 Oct;237(1):213-23.[2] Mulkens TH et al., AJR Am J Roentgenol.

2005 May;184(5):1611-8.[3] European Guidelines on Quality Criteria for

Computed Tomography, EUR 16262 (http://www.drs.dk/guidelines/ct/quality/htmlindex.htm)

[4] Societe Francaise de Radiologie (SFR) (http://www.sfrnet.org/)

[5] Royal Belgium Radiological Society (http://rbrs.org/)


New Opportunities in Cancer Detection with Hepatic AEFThe new application “syngo.CT Onco Function Hepatic AEF” extends diagnostic options in oncology. First studies show promising results in the detection of Hepatocellular carcinoma or liver metastases compared with current methods.[1, 2] Complementary information is obtained from a conventional 3 phase liver scan. The new application is now available on syngo.via application MM Oncology.

By Jochen Dormeier, MD, Computed Tomography, Siemens Healthcare, Forchheim, Germany

Hepatocellular carcinoma (HCC) or metastases might be characterized by a relatively elevated arterial component supply compared with healthy liver tissue. To assist physicians in differentiating healthy from tumorous tissue, the new oncology software “syngo.CT Onco Function-Hepatic AEF” uses the arterial enhancement fraction (AEF) of the liver. Various scientific studies[1, 2, 3] have used the additional mapping and quanti-fiability using the new feature to describe an enhanced diagnostic benefit that can be applied to a variety of clinical problems. These include:■ Primary diagnosis in cases of suspected

HCC or liver metastases■ Follow-up during or after oncological

therapy■ Early detection of tumor recurrence,

e. g. following RF-ablationAEF indicates the ratio of arterial perfu-sion to total perfusion in the liver. The new software automatically registers the unenhanced (native), arterial and portal venous scans of an abdominal multiphase CT and subsequently computes the AEF dataset. The results are presented as a color-coded AEF map which indirectly reflects the ratio of hepatic arterial per-fusion to that of total perfusion. Together with the regular phases of the abdominal CT scan, the AEF dataset is then displayed in a specially adapted layout. The syn-chronized navigation through all phases and the AEF mapping enable radiologists

to compare suspicious findings immedi-ately in all segments. In addition to the visual comparison, the exact AEF values can be measured in freely definable regions of interest. In this way, patho-logical areas can be identified efficiently and further diagnosed using, for example, CT-guided biopsies. A retrospective study was able to show an increase of 17 per-cent in the detection rate for HCC.[1]

1 Color-coded arterial enhancement fraction (AEF) images are calculated from unenhanced (upper left), arterial (upper right) and portal-venous (lower left) abdominal phases. A HCC lesion is clearly shown in segment 8 (arrows). Courtesy of Seoul National University Hospital, Seoul, Republic of Korea

References[1] Kim KW, Lee JM, Klotz E, Park HS, Lee DH,

Kim JY, Kim SJ, Kim SH, Lee JY, Han JK, Choi BI.

1

Quantitative CT color mapping of the arterial enhancement fraction of the liver to detect hepatocellular carcinoma. Radiology 2009; 250:425-434

[2] Joo I, Lee JM, Kim KW, Klotz E, Han JK, Choi BI. Liver metastases on quantitative color mapping of the arterial enhancement fraction from multiphasic CT scans: Evaluation of the hemo-dynamic features and correlation with the chemotherapy response. Eur J Radiol 2011; 80:278-283

[3] Mahnken AH, Klotz E, Schreiber S, Bruners P, Isfort P, Günther RW, Wildberger JE. Volumetric arterial enhancement fraction predicts tumor recurrence after hepatic radiofrequency ablation of liver metastases: initial results. Am J Roentgenol. 2011; 196:573-9

Science


Science

Image Quality in Computed TomographyPart II: High-Contrast Spatial Resolution

By Stefan Ulzheimer, PhD, Computed Tomography, Siemens Healthcare, Forchheim, Germany

After discussing low contrast detectability in part I (SOMATOM Sessions No. 31) the focus here is on another key parameter of imaging systems: spatial resolution. Spatial resolution in high-end computed tomograpy (CT) can thereby be compared very well with that in a simple digital camera.Given that CT is a three-dimensional (3D) imaging method, the spatial resolution also needs to be assessed in 3D. Tradition-ally, this has been done separately in the x/y-direction – the plane in which the

X-ray tube and the detector are located – and in the z-direction along the patient’s longitudinal axis. These are also referred to as in-plane (x/y-direction) and cross-plane (z-direction) resolution.

In-plane resolutionIn-plane resolution can be assessed using intuitive or more objective scientific methods.Let us begin with an intuitive approach, namely how a physical grid of varying dimensions is depicted by the imaging

system. In this approach, a phantom – e. g. CATPHAN® phantom equipped with a CTP 528 high-contrast resolution insert – is imaged by the CT scanner. This insert contains grids of various sizes consisting of high-contrast bars of a set width separated by equal-sized gaps (Fig. 1). Measured from the image, the spatial resolution is then specified in line pairs per centimeter (lp/cm), i.e. the maximum number of bars and gaps per centimeter that can just be visually resolved. For example, a grid with bars 0.5 mm in thick-ness and 0.5 mm gaps contains 10 of these line pairs (bar/gap) per centimeter. If this grid can just be visualized, the maximum visual resolution of the system is 10 lp/cm.When the size of the gaps and bars is reduced, the contrast between the bars decreases until they can no longer be distinguished (Fig. 2A).While this intuitive method is widely accepted, there is a more scientific approach to describe high-contrast reso-lution: the modulation transfer function (MTF). The MTF can be described as how the contrast between our bars reduces with increasing frequency of the bar pat-terns by plotting the contrast against the frequency of the bar patterns (Fig. 2B).Mathematically, the MTF can also be defined as the Fourier transform of the point-spread-function (PSF) of a system. The PSF shows how a point is depicted by a system. Clearly, the ideal system does not exist that can depict a point as a point. Each imaging system will depict it as a somewhat blurred spot or even a completely distorted structure. The MTF approach can also be used as a measure-ment method. A wire that is thin enough but still with sufficiently high contrast to be considered a point is scanned. A Fourier transform of the obtained PSF

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2A can be calculated from the frequency f as d = 1/ (2 f).In the example above, a frequency of 5.9 lp/cm with 10% contrast in the image means that a structure with a minimum size of roughly d = 1/ (2 * 5.9 cm-1) = 0.085 cm = 0.85 mm can be safely resolved in the image.Sometimes other points are specified, e. g. the so-called cut-off frequency where the MTF drops to 0. However, these data points have no clinical relevance. The specification of a resolvable object in mm, therefore, should always be obtained using a visual method or refer to 5–10% of the MTF, where the structure can really be seen in the image.

Cross-plane resolutionIn general, the same principles dis-cussed above also apply in the z-direction, especially as isotropic datasets are now possible following the introduction of multislice scanners.Traditionally, the resolution in the z-direction was much lower than in the x/y-plane and therefore the appearance of individually acquired slices was much more obvious than today.Consequently, in the z-direction slice thickness is still the most commonly used parameter to characterize spatial resolution.Again, there are various ways to measure either spatial resolution in the z-direction or the slice thickness. A straightforward method is to take the same grids as used to assess in-plane resolution, only tilted by 90°. A method recommended by the International Electrotechnical Commission (IEC) uses wire or strip ramps oriented parallel to the x- or y-axis but tilted against the x/y-plane.[4] Using basic trigonome-try, the slice width can be determined from the length of the wire or strip that is depicted in one image. A correction may be necessary to account both for the thickness of the wire or strip itself and for the in-plane reconstruction properties (e.g. the kernel) that influence the visible length of the wire or strip in the image.The best method to determine the slice thickness is to measure the actual PSF in the z-direction again. In CT this is usually referred to as Slice Sensitivity Profile (SSP).

again gives the MTF. In CT, the MTF depends on many factors that cannot be changed but also on some that can be changed by the user.

Interpreting manufacturer specificationsIn practice, only a small number of para-meters are given in the manufacturer’s data sheets and so it is important to inter-pret these correctly. Often only a few MTF data points in dedicated high-reso-lution scan modes are specified. A more relevant high-contrast specification might look like this:5.9 lp/cm@10% MTF (in typical body mode)This means that structures with frequen-cies of 5.9 lp/cm are depicted with a con-trast of 10% in the images in typical body

mode. In practice, the contrast differ-ences still seen in the images will also depend on the noise level in the images. In typical clinical situations CT contrast differences below 5–10% can no longer be detected by an observer.[1] Therefore, clinically relevant specifications should state the frequency at 5–10% MTF and the exact scan and reconstruction para-meters should be given.Intuitively, spatial resolution is related to the smallest object size that can be resolved. The method described to mea-sure lp/cm can, however, be directly trans-lated to any object size since one line pair consists of two structures of equal size. The frequency f of the bar patterns can be calculated from the width d of the bar patterns, as f = 1/ (2 d). Re-arranging this equation, the minimum object size d


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Typically, a thin gold disc is moved along the z-direction and the relative contrast of the disc is plotted against its z-position (Fig. 3). Intuitively, the profile of a slice has a rectangular shape like a slice of bread. In CT, however, the SSP may differ from that ideal shape depending on the scan mode. In sequential scanning the shape is trapezoidal due to the geometry of a CT scanner; in spiral CT the profile is bell-shaped. If one moves the thin gold disc slowly into the slice, it does not suddenly appear in full contrast but the contrast slowly increases until it reaches a maximum in the middle of the slice.The slice thickness is now defined as the full-width-at-half-maximum (FWHM) of the SSP.[4] The FWHM is the width of the slice profile when the contrast reduces by 50%.

If the SSP shape differs greatly from the rectangular shape, the resolution can be improved by reconstructing overlapping slices. Typically, 2-3 overlapping slices per nominal slice width yields the best compromise between resolution and additional data volume generated.[1] This method can produce, for example, a visual resolution of 0.3 mm from slices that are nominally 0.5 mm thick.

Siemens Technologies to Optimize Spatial ResolutionSpatial resolution depends highly on the sampling of the data acquired. Siemens CT scanners use various oversampling techniques. Oversampling avoids aliasing, improves resolution and reduces noise. For in-plane imaging, a flying focal spot of the X-ray tube is used, i. e. two focal

spot positions for the same projection angle shifted by half the detector width. This doubles the number of data points within the plane without a dose increase as only half the dose is applied for each projection. The detector channels are also shifted by one quarter detector width within one rotation so that opposite pro-jections yield slightly different data points. This again doubles the number of projec-tions for image reconstruction. Siemens uses the z-Sharp feature unique to the Siemens STRATON® tube, which uses a flying focal spot in the X-ray tube in the z-direction, too.[2] This provides the highest resolution entirely independent of the spiral pitch and at all scan speeds. The majority of systems from other vendors are still bound to discrete pitch values that offer EITHER high scan speed OR high image quality.A small and stable focal spot of the X-ray tube is also an important factor in achieving optimal spatial resolution both in-plane and in the z-direction. The Siemens STRATON tube offers a focal spot of 0.7 x 0.7 mm for ultra high-resolution applications such as inner-ear scanning and a flying focal spot of 0.9 x 1.1 mm for standard applications.Compared to systems with conventional detectors, the Siemens Stellar Detector enables reconstruction of slices with an actual effective slice width of 0.5 mm and has been shown to improve stenosis grading significantly due to improved spatial resolution with reduced image noise.[3] Other vendors may specify the same slice thickness by tweaking the tolerances recommended by the IEC. The IEC recommends a deviation of up to 0.5 mm from the specified slice width for thicknesses below 1 mm.[4] This could mislead users into believing that a slice of 0.8 mm, for example, is actually 0.5 mm thin by specifying 0.5 mm in the user interface (Fig. 3). It is, however, important to note that detector width alone does not determine spatial resolu-tion. Even if the detector elements have a width of 0.5 mm, the same is not nec-essarily true for the reconstructed slice widths as many factors play a role in achieving maximum spatial resolution.Another way to increase spatial resolu-

2B Plotting the contrast against the resolution, produces the MTF for the B50 kernel and this scan mode. The MTF completely characterizes the high-contrast resolution of this dedicated scan mode in combination with this kernel.

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References[1] Willi A. Kalender. Computed Tomography:

Fundamentals, System Technology, Image Qual-ity, Applications, Publicis Publishing (2011)

[2] Flohr TG, Stierstorfer K, Ulzheimer S, Bruder H, Primak AN, McCollough CH. Image reconstruc-tion and image quality evaluation for a 64-slice CT scanner with z-flying focal spot. Med Phys. 2005 Aug;32(8):2536-47.

[3] Morsbach F et al. Stenosis quantification in coronary CT angiography: impact of an integrated circuit detector with iterative reconstruction. Invest Radiol. 2013 Jan;48(1):32-40.

[4] IEC 61223-3-5, Ed.1 (2004-08) Evaluation and routine testing in medical imaging departments – Part 3–5: Acceptance tests – Imaging perfor-mance of computed tomography X-ray equipment

[5] Hsieh J, Gurmen OE, King KF. Investigation of a solid-state detector for advanced computed tomography. IEEE Trans Med Imaging. 2000 Sep;19(9):930-40.

tion, albeit at the price of higher dose is the use of dedicated grids. On all high-end scanners in the Siemens Definition class Ultra High Resolution (UHR), grids are available both in-plane and in the z-direction. These can be moved in front of the detector to reduce the aperture of the detector elements by 50% in both planes. This option is mainly used in inner-ear or bone imaging.Siemens’ proprietary scintillator material Ultra Fast Ceramics (UFC™) offers high X-ray absorption, short decay times, and extremely low afterglow, key parameters for high spatial resolution. The decisive properties of scintillator materials that are important for spatial resolution are decay time and afterglow. Both charac-terize the light output of the scintillator after the X-rays are switched off. UFC has decay characteristics that are optimized with respect to all other system parame-ters, especially the length of one projection. It offers a consistent decay time of 2.5 microseconds, and an afterglow

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and versatile image processing. The same applies to a CT scanner at more than 10,000 times the price of a simple digital camera.

below 10–4 after 1 millisecond and 10–5

after 10 milliseconds. Today, other ven-dors still use afterglow correction mech-anisms [5] since long decay time and high afterglow can ruin spatial resolution due to blurring between the projections. Yet, increasing scintillator speed beyond cer-tain limits no longer makes sense if it is significantly faster than the duration of one projection.Other important factors for a well-bal-anced system with optimized spatial resolution are the number of projections per rotation, an optimized scanner geo-metry that takes all other parameters into account. Of course, a wide range of optimized reconstruction kernels that can address all clinical challenges is essential as well.Returning to the digital camera men-tioned at the start, we now know that the number of megapixels is not enough to characterize its performance. Much more important is a well-balanced system with quality, harmonized components


syngo Evolve Update for SOMATOM Definition Family MembersBy Jutta Reindler, Computed Tomography, Siemens Healthcare, Forchheim, Germany

The syngo Evolve non-obsolescence program from Siemens makes innovations possible even in installed CT scanners. More than 1,000 systems in operation worldwide are currently being updated with the rollout of the new syngo CT 2012B software.Customers with SOMATOM® Definition Flash and AS systems installed in 2009 and 2010 and all SOMATOM Definition customers can benefit from the new syngo CT 2012B software. It includes the following features to enhance routine workflow:■ Password protected scan protocols:

Protection is now available to avoid unauthorized modifications. This functionality requires a password in order to use the Scan Protocol Assistant and save changed scan protocols.

■ Customized anonymization attri-butes: Patient data can be anonymized. For this, the content has to be taken offline. The software then allows differ-ent attributes, such as format or name, to be configured.

■ Improvements to syngo Expert-i*: Expert-i enables interaction with the syngo CT Workplace from virtually any-where in the hospital. With the syngo Evolve update, Expert-i now supports dual monitor use as well as dual screen display (switch using hot key).

■ Improvements to the Patient Browser – search by “latest exami-nation date”: The new software allows a search for the latest examination date for a particular patient. Thus, the data from previous examinations required for a follow-up can be found efficiently. This can ease the daily workflow.

■ The FAST CARE Technology is now available: The FAST CARE Technology* is now also available to SOMATOM Definition Evolve customers accelerat-ing workflow and lowering radiation exposure to unseen levels. For more information on the features included please see: www.siemens.com/fast-care

Special featuresSome features are offered especially to individual members of the SOMATOM Definition Family. One such feature is syngo Dual Energy** as part of Evolve for SOMATOM Definition Flash. This includes FAST Dual Energy enabling easy and intu-itive immediate 3D-reconstruction of acquired Dual Energy data. WorkStream4D reconstructs axial, sagittal, coronal, or

Password protection is now available to avoid unauthorized modifications.

double-oblique images directly from standard Dual Energy scanning protocols. There is no need to generate the individ-ual image series first. The elimination of time-consuming and error-prone manual reconstruction steps makes the workflow much faster.In addition, using FAST Dual Energy for reconstruction significantly reduces the data volume and saves considerable film-ing and archiving resources. After installation, e-learning CDs and dedicated application training help the customers to make the full use of the new scanner capabilities.

** FAST Planning features to be purchased separately ** Requires Dual Energy Scanning with selective

Photon Shield

Customer Excellence


Customer Excellence

Thorsten Johnson, MD, Associate Professor of Radiology hosted an exciting Dual Energy CT workshop at the Siemens CT headquarters in Forchheim.

Walter Huda, PhD, from the Medical University of South Carolina, focuses on dose and image quality in his new webinar.

Workshop on Dual Energy at CT Headquarters in Germany By Axel lorz, Computed Tomography, Siemens Healthcare, Forchheim, Germany

CT Physics Made Easy – with New WebinarBy Axel lorz, Computed Tomography, Siemens Healthcare, Forchheim, Germany

As part of Siemens Healthcare long-established tradition of offering training, a workshop on Dual Energy CT was held in February 2013. Speaker was Thorsten Johnson, MD, Associate Professor of Radi-ology and Head of Computed Tomography at Munich University Hospital, Germany. Dual Energy scanning has increasing clin-ical relevance and so radiologists were quick to fill the 12 available places. Par-ticipants came from all parts of the world to attend the course at the headquarters of Siemens CT in Forchheim, Germany. The two-day training session included presentations on both the clinical bene-fits and physical principles of Dual and Single Source Dual Energy CT.

A hands-on session at a SOMATOM® Definition Flash scanner and at work- stations for extended case review was included in the workshop. Course direc-tor and specialist Thorsten Johnson covered all the twelve FDA cleared clini-cal Dual Energy applications with an emphasis on the optimization of scan parameters. As an early pioneer of Dual Energy CT and in view of his extensive daily practice at Munich University Hospital, Johnson made the workshop a particularly exciting experience. After the workshop, participants left fully equipped with the latest information on work at the forefront of CT Dual Energy technology.

For further information and booking options: www.siemens.com/ SOMATOMEducate

www.siemens.com/ clinicalwebinars

Siemens Healthcare has added a new webinar focusing on CT physics to their educational program. In this session, Walter Huda, PhD, Medical University of South Carolina, Charleston, USA provides an introduction to physics for CT and practical tips on mastering the trade-off between dose and image quality. A well-

known scientist and professor of radiology internationally, Walter Huda is actively involved in the clinical application of med-ical imaging. In his everyday work, one of his main concerns is to maximize diag-nostic information while keeping patient dose “as low as reasonably achievable” (ALARA).In six half-hour sessions, Huda guides the listener through:■ CT dose■ Image quality■ CARE Dose4D■ CARE kV■ Clinical techniques■ Clinical practiceFrom the basics of CT physics to advanced dose-saving techniques, Walter Huda

explains ways to reduce the amount of radiation while still achieving the best possible image quality. In addition to a strong theoretical background, Huda offers many practical tips. Participants learn, for example, the influence of tube voltage on dose and contrast-to-noise ratio and hear a discussion about the impact on bariatric or pediatric patient scans. After completing the six modules, the participant will have a thorough understanding of how to best use all the SOMATOM® dose-saving features.

Customer Excellence

FAST Dual Energy (DE) as part of the syngo CT 2012B software recently has been introduced to the Siemens Dual Source scanners.

3D reconstruction fast and smooth

FAST DE can accelerate workflow by enabling easy and intuitive direct 3D recon-structions of acquired DE data (Fig. 1).

FAST DE has been included into WorkStream 4D. Thus often time-con-suming manual reconstruction steps have been eliminated. In the “Recon” card, different reconstruction series are available: A+B+M / A+B / FAST DE (F).

With FAST DE (F) the generation of 3D reconstructed para-axial, sagittal and coronal images will now be possible by directly using the CT data. These 3D series – indicated by an F in the series name – can then be easily incorporated into routine CT protocols.

Saving storage spaceCalculating a FAST DE series is not only much quicker than an A+B+M series. Also, storing just one rather than three sets of data reduces overall data volume. A separate autotransfer functionality for each series is also available.

Reducing metal artifacts Both the mixed image series and FAST DE image series are a combination of the acquired low and high kV datasets (Fig. 2). The mixing ratio can be adjusted by set-ting the composition factor to define the linear weight of the low kV images. The intensity of the high kV images is derived from the composition factor. A FAST DE series can be reconstructed with a nega-tive composition factor making it possi-ble to reduce metal artifacts.

Tips & Tricks: How to Accelerate Reconstruction of Dual Energy Data By Patricia Jacob, Computed Tomography, Siemens Healthcare, Forchheim, Germany

1

2

2 To adjust the composition factor, use the composition slider for the mixed and/or FAST DE image series. Symbols indicate the recommended composition factors, for example for non-contrast and vascular examinations.

1 For a swifter run, select FAST DE in the “Recon” card and then choose 3D as the recon type.


Customer Excellence

Clinical Workshops 2013As a cooperation partner of many renowned hospitals, Siemens Healthcare offers continuing CT training programs. In a wide range of workshops, clinical experts share latest experiences and options in clinical CT imaging.

In addition, you can always find the latest CT courses offered by Siemens Healthcare at www.siemens.com/SOMATOMEducate

Short Description Date location Title Contact

World Congress of Thoracic Imaging June, 8–11 Seoul, Korea WCTI www.wcti2013.org

International Society for Computed Tomography

June, 17–20 Washington DC, USA ISCT www.mdctcourse.com

European Conference on Interventional Oncology

June, 19–22 Budapest, Hungary ECIO www.ecio.org

Society of Cardiovascular Computed Tomography

July, 11–14 Montreal, Canada SCCT www.scct.org

European Society of Cardiology Aug, 31–Sept, 4 Amsterdam, The Netherlands

ESC www.escardio.org

American Society for Radiation Oncology

Sept, 22–25 Atlanta, USA ASTRO www.astro.org

Radiological Society of North America

Dec, 1–6 Chicago, USA RSNA www.rsna.org

Upcoming Events & Congresses 2013

Workshop Title / Special Interest Date location Course Director link

Hands-on at the ESGAR Congress / Colonography

June, 4–7 Barcelona, Spain

ESGAR – Prof. Carmen Ayuso, MD

www.esgar.org

Oncology Imaging Course 2013 / Oncology

June, 27–29 Dubrovnik, Croatia

OIC – Prof. Maximilian Reiser, MD

www.oncoic.org

Clinical Workshop on Cardiac CT / Cardiac

July, 17–19 Munich, Germany

Siemens Healthcare – Prof. Christoph Becker, MD

www.siemens.com/SOMATOMEducate

Workshop for Physicists Oct, 22–23 Forchheim, Germany

Siemens Healthcare www.siemens.com/SOMATOMEducate

CTA Interpretation Course / Cardiac Nov, 7–8 Erlangen, Germany

Siemens Healthcare – Prof. Stefan Achenbach, MD

www.siemens.com/SOMATOMEducate

The term “partner” does not imply a legal partnership or joint venture relationship.



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Note in accordance with § 33 Para.1 of the German Federal Data Protection Law: Despatch is made using an address file which is maintained with the aid of an automated data processing system.SOMATOM Sessions with a total circulation of 25,000 copies is sent free of charge to Siemens Computed Tomography customers, qualified physicians and radiology departments throughout the world. It includes reports in the English language on Computed Tomography: diagnostic and therapeutic methods and their application as well as results and experience gained with corresponding systems and solutions. It introduces from case to case new principles and procedures and discusses their clinical potential.The statements and views of the authors in the individual contributions do not necessarily reflect the opinion of the publisher.The information presented in these articles and case reports is for illustration only and is not intended to be relied upon by the reader for instruction as to the practice of medicine. Any health care practitioner reading this information is reminded that they must use their own learning, training and expertise in dealing with their individual patients. This material does not substitute for that duty and is not intended by Siemens Medical Solutions to be used for any purpose in that regard.

The drugs and doses mentioned herein are consistent with the approval labeling for uses and/or indications of the drug. The treating physician bears the sole responsibility for the diagnosis and treatment of patients, including drugs and doses prescribed in connection with such use. The Operating Instructions must always be strictly followed when operating the CT System. The sources for the technical data are the corresponding data sheets. Results may vary.Partial reproduction in printed form of individual contributions is permitted, pro-vided the customary bibliographical data such as author’s name and title of the contribution as well as year, issue number and pages of SOMATOM Sessions are named, but the editors request that two copies be sent to them. The written consent of the authors and publisher is required for the complete reprinting of an article.We welcome your questions and comments about the editorial content of SOMATOM Sessions. Manuscripts as well as suggestions, proposals and information are always welcome; they are carefully examined and submitted to the editorial board for attention. SOMATOM Sessions is not responsible for loss, damage, or any other injury to unsolicited manuscripts or other materials. We reserve the right to edit for clarity, accuracy, and space. Include your name, address, and phone number and send to the editors, address above.

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Bauer, Ralf W., MD, Goethe University Frankfurt, Germany

Ching So, Man, MD, St. Teresa’s Hospital, Kowloon, Hong Kong SAR, China

Fukuda, Nobuaki, MD, National Hospital Orga-nization Takasaki General Medical Center, Japan

Hagspiel, Klaus D., MD, University of Virginia, USA

Hiroi, Shitoshi, MD, National Hospital Organi-zation Takasaki General Medical Center, Japan

Iwase, Haruka, MD, National Hospital Organi-zation Takasaki General Medical Center, Japan

Kobayashi, Hiroaki, MD, National Hospital Orga-nization Takasaki General Medical Center, Japan

Kerl, J. Matthias, MD, Goethe University Frankfurt, Germany

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Ming Wong, Chi, MD, St. Teresa’s Hospital, Kowloon, Hong Kong SAR, China

Negishi, Chikashi, MD, National Hospital Organi-zation Takasaki General Medical Center, Japan

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Rumboldt, Zoran, MD PhD, Medical University of South Carolina, Charleston, SC, USA

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Schulz, Boris, MD, Goethe University Frankfurt, Germany

Shizuka, Takehito, MD, National Hospital Organi-zation Takasaki General Medical Center, Japan

Sun, Hongtu, MD, Panshi City Hospital, Jilin, P. R. China

Vogl, Thomas J., MD, Goethe University Frankfurt, Germany

Yanagisawa, Saburou, MD, National Hospital Organization Takasaki General Medical Center, Japan

Yuzhang, Wu, MD, Panshi City Hospital, Jilin, P. R. China

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Siemens reserves the right to modify the design, packaging, specifications and options described herein without prior notice. Please contact your local Siemens sales representative for the most current information.

Note: Any technical data contained in this document may vary within defined tolerances. Original images always lose a certain amount of detail when reproduced.

The statements by Siemens’ customers described herein are based on results that were achieved in the customer’s unique setting. Since there is no “typical” hospital and many variables exist (e.g., hospital size, case mix, level of IT adoption) there can be no guarantee that other customers will achieve the same results.

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Global Business Unit

Siemens AGMedical SolutionsComputed Tomography& Radiation OncologySiemensstraße 191301 Forchheim GermanyPhone: +49 9191 18-0 www.siemens.com/healthcare

local Contact Information

Asia/Pacific:Siemens Medical SolutionsAsia Pacific HeadquartersThe Siemens Center60 MacPherson RoadSingapore 348615Phone: +65 6490-6000 www.siemens.com/healthcare

Canada:Siemens Canada LimitedHealthcare Sector2185 Derry Road WestMississauga ON L5N 7A6CanadaPhone: +1 905 819-5800 www.siemens.com/healthcare

Europe/Africa/Middle East:Siemens AGHealthcare SectorHenkestraße 127D-91052 ErlangenGermanyPhone: +49 9131 84-0 www.siemens.com/healthcare

latin America:Siemens S.A.Medical SolutionsAvenida de Pte. Julio A. Roca No 516, Piso 7C1067ABN Buenos Aires ArgentinaPhone: +54 11 4340-8400 www.siemens.com/healthcare

USA:Siemens Medical Solutions U.S.A., Inc.51 Valley Stream ParkwayMalvern, PA 19355-1406USAPhone: +1-888-826-9702 www.siemens.com/healthcare

Global SiemensHealthcare Headquarters

Siemens AGHealthcare SectorHenkestraße 12791052 ErlangenGermanyPhone: +49 9131 84-0www.siemens.com/healthcare

Global Siemens Headquarters

Siemens AGWittelsbacherplatz 280333 MuenchenGermany

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Documents

Somatom sessions 32