Clinical Advancements

Transcription

1 A p u b l i c a t i o n p r o d u c e d b y T o s h i b a M e d i c a l S y s t e m s Clinical Advancements i n v o l u m e t r i c C T Cardiac CT: 64-Slice and Beyond Cardiac CT: Physician Roundtable Characterization of Vulnerable Plaque The Next Revolution in CT Clinical Case Studies F ebruar y 2006

2 Heart rates are variable, image quality shouldn't be. Aquilion 64, the most advanced 64 detector CT system available delivers: True volumetric imaging 64 simultaneous 0.5mm slices acquired per rotation Superior spatial resolution at 0.35mm for small vessel detail Superior low-contrast resolution for soft plaque visualization Innovative workflow solutions like SURE Cardio for automated cardiac scanning To learn how the newest addition to the award-winning Aquilion series of scanners can enhance your diagnostic insight, visit our Web site, or call (800) w w w. m e d i c a l. t o s h i b a. c o m

3 Contents 4 The Next Revolution: 256 * -Slice CT Richard Mather, PhD 10 How Effective is Cardiac CT? Physicians Speak Out Gerald M. Burma, MD, PhD, Peter S. Fail, MD, Steven R. Gunberg, DO, Bruce S. Lachterman, MD, Ron M. Peshock, MD, PhD 14 Aquilion 64 Case Study Incidental Finding of Metastatic Lesion 15 Aquilion 64 Case Study Coronary CTA: Anomalous Left Coronary Artery 16 Characterizing Vulnerable Plaque 21 Aquilion 64 Case Study Coronary CTA: Multiple Mixed Plaques 22 Practical Matters Education and Reimbursement Gerald M. Burma, MD, PhD, Peter S. Fail, MD, Steven R. Gunberg, DO, Bruce S. Lachterman, MD, Ron M. Peshock, MD, PhD 26 Aquilion 64 Case Study Coronary CTA: Stent Follow-up 27 Aquilion 64 Case Study Coronary CTA: Multiple Vessel Disease COVER: 3D VR Cardiac CTA using Toshiba s clinically validated SURE Plaque software. Case study images courtesy of Manhattan Diagnostic Radiology and Woodlands North Houston cardiology Editor: Jim Burch Managing Editor & Production: Jannay Morrison * Work in progress. Printed in USA A publication produced by Toshiba Medical Systems, Inc. 2006

4 The Next Revolution: * 256 * -Slice CT Once relegated mostly to cranial imaging, multi-slice CT has undergone a technological revitalization that s made it the modality of choice in an increasingly diverse range of clinical applications. But, as a look back reveals, the road from one slice to 256 is paved with quantum leaps in technical innovation especially in detector design and technology. Author Richard Mather, PhD Senior Manager, CT Clinical Science Toshiba America Medical Systems * Work in progress. Early Breakthroughs Each technological breakthrough in CT removed old barriers and challenged the clinical community to think about CT imaging in new ways. The introduction of slip ring technology and helical scanning 1, for example, made it possible to cover volumes of anatomy within a single breath-hold, thus paving the way for lung and body imaging. Similarly, four-slice technology enabled the first truly volumetric CT scans. Toshiba s Aquilion 4-detector, a hybrid detector array, created a choice between wide anatomic coverage or thin resolution slices. The Quad employs 0.5mm slice thickness to obtain isotropic resolution for images needing high resolution such as musculoskeletal imaging or Circle of Willis CTA. It can also employ thicker slices to provide large coverage in a single breath-hold when imaging the chest and abdomen. An entirely new generation of CT exams such as CT angiography, including CT pulmonary angiography, CT colonography and CT urography was made possible by this new technology. This new flood of clinical applications, however, came with the challenge of handling larger, more complex datasets which required the routine use of multiplanar and 3D images to aid diagnosis. Sixteen Slices and Shorter Breath-holds It was not until the sixteen slice systems became available that the next breakthrough in CT was realized. With the Aquilion 16 it became possible to cover the entire lung field with 0.5mm slices in about 13 seconds, which is an achievable breath-hold. It was also possible to keep up with the contrast bolus in a peripheral runoff exam. This ability to accurately image virtually any anatomy quickly made the Aquilion 4 February 2006 A publication produced by Toshiba Medical Systems

5 From slice systems, the breath-hold time for helical scanning of the heart has been significantly reduced. However, it is only with the 256-slice system that the entire heart can be covered in a single rotation. 16 the workhorse of many radiology departments. However, it was vascular imaging and musculoskeletal that brought Aquilion s clinical versatility to the forefront. Cardiac Imaging The Aquilion 16 produced the fine isotropic resolution necessary to depict tiny coronary vessels, while achieving a manageable breath-hold of less than 30 seconds. While there were some published papers detailing the use of four-slice coronary imaging 2,3,4,5, it was not until sixteen slice technology that widespread clinical interest took hold 6,7,8,9,10,11. Unfortunately, with breath-hold times in the second range, coronary Coronary imaging with the sixteen is not necessarily routine imaging with the sixteen is not necessarily routine, as a percentage of the vessel segments are often nonassessable due to motion artifact because many patients were unable to tolerate the long breath-hold required. 64-slice Eliminates Tradeoffs Routine coronary artery imaging has only recently emerged with the advent of true 64-slice technology. Unlike any predecessors, Toshiba s Aquilion 64 covers its entire 32mm detector with 0.5mm slices, which completely eliminates any trade-off between coverage and resolution. With the Aquilion 64, clinical applications can be performed at 64 x 0.5mm slices, yielding fine isotropic resolution with excellent speed and coverage. This means that the entire coronary tree can be imaged in 6-to-9 seconds. The main advantage of these short breath-holds is that the patient s heart rate typically remains regular over this period, resulting in vastly A publication produced by Toshiba Medical Systems February 2006

6 T h e N e x t R e v o l u t i o n : s l i c e C T improved coronary image quality since conventional, non-adaptive cardiac reconstruction algorithms are most effective when the heart rate is steady. Patient tolerance of the exam is also greatly improved. Reconstruction Algorithms For patients with erratic heart rates, ectopic beats or atrial fibrillation, a good adaptive segmented reconstruction algorithm can minimize motion artifacts and significantly reduce banding and other misregistration artifacts 12,13. Dewey et al showed that Toshiba s SURE Cardio adaptive segmented reconstruction algorithm notably improved the sensitivity, specificity and accuracy of detecting significant stenoses and measurably reduced the number of non-assessable arteries over half-scan reconstructions of the same data 14. Whole-Organ Coverage While the 64-slice technology makes coronary artery imaging routine, its 32mm of coverage still isn t large This will help make coronary CT a truly routine and mainstream exam enough to image the entire heart in a single rotation. One technology that has been proposed for true volumetric imaging is the flat panel CT system 15,16. This system s main advantage is spatial resolution, which can be as low as 0.25mm in all dimensions. However, it is plagued by a limited field of view, slow scan speeds (which limit the temporal resolution), poor scatter rejection and poor low-contrast detectability. These limitations make the flat panel system a poor candidate for a cardiac scanner, which needs good temporal and low contrast resolution along with its spatial resolution. Dynamic cardiac imaging would not be possible with a flat panel system. While a 128-slice system would provide 64mm of coverage in a single rotation, it still does not have enough coverage to image a 120mm heart without moving the table. This can lead to potential misregistration artifacts at the volume boundaries and, more importantly, would limit dynamic studies such as first pass perfusion. An ideal organ scanner should have the ability to image the entire organ in a single rotation of the CT gantry with no table motion. For true volumetric cone beam CT to realize its full potential and enjoy broad clinical acceptance, it must acquire wide-area coverage while maintaining the advantages of conventional CT: fine spatial resolution, fast temporal resolution, and above all, superior low-contrast resolution. Otherwise, it becomes a niche system with limited clinical utility that can only be used for a limited number of applications. Toshiba s 256-slice System Achieving complete coverage of the heart or other organs within a single rotation requires a system capable of covering at least 120mm of anatomy with no table movement. Toward this end, Toshiba, in cooperation with the NEDO (New Energy and Industrial Technology Development Organization) in Japan, has successfully 6 February 2006 A publication produced by Toshiba Medical Systems

7 T h e N e x t R e v o l u t i o n : s l i c e C T developed two prototype 256-slice CT systems 17 based on the Aquilion platform s core technology. Utilizing Toshiba s proven gantry design and high-efficiency detector material, these systems cover 128mm of anatomy with 0.5mm slices, producing fine, isotropic resolution of the heart during a single gantry rotation. The patented detector material featured on the prototypes offer the same excellent, low-contrast performance as the rest of the Aquilion line. Fast decay time and low afterglow properties ensure that the systems are fast enough for dynamic cardiac imaging, while excellent stopping power and high light-output make them highly dose efficient. Clinical Development Over the past several years, there have been numerous reports published detailing the design, development and performance of the 256-slice scanner 18,19,20,21*. In 2004, Mori et al compared several image quality metrics of the prototype 256-slice system with those of a conventional CT system. They found that the prototype 256 system has very similar spatial resolution, noise and uniformity between the two systems 18. In another study, Mori et al showed that the prototype 256-slice scanner performed equally as well in standard radiographic examinations as a conventional system 22. After scanning eight healthy volunteers on the prototype system with axial exams of the head, chest, abdomen and pelvis, they found image quality equivalent to conventional CT using the same dose. Imaging Large Organs The primary benefit of wide volume coverage is the ability to perform A publication produced by Toshiba Medical Systems February 2006

8 T h e N e x t R e v o l u t i o n : s l i c e C T dynamic examinations of large organs, such as the heart and liver. Funabashi et al examined Toshiba s prototype 256-slice scanner to evaluate its blood flow dynamics in porcine hearts and livers 23. This study showed the unit s clear advantage over conventional systems in obtaining dynamic perfusion information from the entire liver. With a conventional system, it was possible to acquire phasic information of the entire volume by performing multiple helical runs or obtain dynamic information over a very limited anatomic volume, but not both. Researchers also demonstrated the Toshiba prototype s advantages in visualizing cardiac shunt flow and other blood flow disorders. Most recently, Kondo et al used the 256-slice system to image the hearts of two human volunteers 24. They showed that the system could successfully visualize the coronaries, myocardial contraction and myocardial enhancement during a single imaging exam. They also found the system s radiation dose to be approximately 2mSv per second, allowing either very lowdose, single-shot coronary imaging or low-dose dynamic imaging that can visualize the coronaries while concurrently obtaining detailed perfusion information. For about the same amount of radiation as today s 64-slice CT, dynamic myocardial perfusion imaging with 12cm coverage can be obtained at the same time. 256 Detector CT image of Human Heart with 128mm coverage per rotation. Cone-Angle Challenges Of course, no new system is without technological challenges. One such challenge with the 256-slice prototype is related to increased cone angle. Without high-quality reconstruction algorithms, cone-beam artifacts could limit the system s diagnostic capability. Taguchi, however, showed that a modified February 2006 A publication produced by Toshiba Medical Systems

9 T h e N e x t R e v o l u t i o n : s l i c e C T Feldkamp-based algorithm can effectively limit artifacts due to the cone angle. He also extended the algorithm to include dynamic data produced by the system to accurately reconstruct all four informational dimensions 25,26. Revolutionizing CT. Again. As CT scanner technology has advanced, each successive system has built upon CT s proven clinical utility with the best performance advances at 4-, 16-, and 64-slice, bringing a wealth of new clinical applications. As shown through the early research on the system, Wide volume coverage gives the ability to perform dynamic examinations of large organs the 256-slice CT scanner provides the next quantum leap in CT technology. Finally it will be realistic to obtain whole organ evaluation and perfusion in a single rotation. This will bring about many new areas of study in functional CT imaging. Furthermore, with prospective cardiac triggering, it may be possible to acquire images of the coronary arteries with as little as 2mSv of dose. This will help make coronary CT a truly routine and mainstream exam. Built on proven detector and gantry technology with the ability to not only perform well on conventional CT applications but also on a wealth of new applications, Toshiba s 256-slice CT system will revolutionize CT imaging, again. CA References 1. Mori I, 1986, Computerized Tomographic Aparatus Utilizing a Radiation Source, U.S. Patent No. 4,630, Becker CR, Knez A, Ohnesorge B, Schoepf UJ, Reiser MF, 2004, Imaging of noncalcified coronary plaques using helical CT with retrospective ECG gating, Am J Roentgenol, 175(2): Achenbach S, Ulzheimer S, Baum U, Kachelriess M, Ropers D, Giesler T, Bautz W, Daniel WG, Kalender WA, Moshage W, 2000, Noninvasive Coronary Angiography by Retrospectively ECG-Gated Multislice Spiral CT. Circulation, 102(23): Dirksen MS, Bax JJ, Blom NA, Schalij MJ, Jukema WJ, Vliegen HW, van der Wall EE, de Roos A, Lamb HJ, 2002, Detection of malignant right coronary artery anomaly by multi-slice CT coronary angiography, Eur Radiol., Dec, 12 Suppl 3:S Schroeder S, Kopp AF, Baumbach A, Meisner C, Kuettner A, Georg C, Ohnesorge B, Herdeg C, Claussen CD, Karsch KR, 2001, Noninvasive detection and evaluation of atherosclerotic coronary plaques with multislice computed tomography. J Am Coll Cardiol, 37(5): Nieman K, Cademartiri F, Lemos PA, Raaijmakers R, Pattynama PM, de Feyter PJ, 2002, Reliable noninvasive coronary angiography with fast submillimeter multislice spiral computed tomography, Circulation 2002;106(16): Ropers D, Baum U, Pohle K, Anders K, Ulzheimer S, Ohnesorge B, Schlundt C, Bautz W, Daniel WG, Achenbach S, 2003, Detection of coronary artery stenoses with thin-slice multi-detector row spiral computed tomography and multiplanar reconstruction. Circulation, 107(5): Hoffmann MH, Shi H, Schmitz BL, Schmid FT, Lieberknecht M, Schulze R, Ludwig B, Kroschel U, Jahnke N, Haerer W, Brambs HJ, Aschoff AJ, 2005, Noninvasive Coronary Angiography With Multislice Computed Tomography, JAMA 293(20): Hamoir XL, Flohr T, Hamoir V, Labaki L, Tricquet JY, Duhamel A, Kirsch J, 2005, Coronary arteries: assessment of image quality and optimal reconstruction window in retrospective ECG-gated multislice CT at 375-ms gantry rotation time, Eur Radiol, 15(2): Bley TA, Ghanem NA, Foell D, Uhl M, Geibel A, Bode C, Langer M, 2005, Computed tomography coronary angiography with 370-millisecond gantry rotation time: evaluation of the best image reconstruction interval, J Comput Assist Tomogr.;29(1): Lawler LP, Pannu HK, Fishman EK, 2005, MDCT evaluation of the coronary arteries, 2004: how we do it--data acquisition, postprocessing, display, and interpretation, AJR Am J Roentgenol., 184(5): Hein I, Taguchi K, Silver MD, Kazama M, Mori I, 2003, Feldkamp-based cone-beam reconstruction for gantry-tilted helical multislice CT, Med. Phys. 30(12), Mather R, 2005, Meeting the Cone Beam Challenge Aquilion s SURECardio and TCOT, Clinical Advancements in Volumetric CT, a Diagnostic Imaging supplement, October, Dewey M, Laule M, Krug L, Schnapauff D, Rogalla P, Rutsch W, Hamm B, Lembcke A, 2004, Multisegment and Halfscan Reconstruction of 16-Slice Computed Tomography for Detection of Coronary Artery Stenoses, Invest Radiol, 39(4): Nikolaou K, Flohr T, Stierstorfer K, Becker CR, Reiser MF, 2005, Flat panel computed tomography of human ex vivo heart and bone specimens: initial experience, Eur. Radiol., 15(2): Mahnken AH, Seyfarth T, Flohr T, Herzog C, Stahl J, Stanzel S, Kuettner A, Wildberger JE, Gunther RW, 2005, Flat-panel detector computed tomography for the assessment of coronary artery stents: phantom study in comparison with 16-slice spiral computed tomography, Invest Radiol, 40(1): Katada K, 2004, Current status and future prospects of MDCT. Proceedings of the Third International MDCT Sypmposium, Mori S, Endo M, Tsunoo T, Kandatsu S, Tanada S, Aradate H, Saito Y, Miyazaki H, Satoh K, Matsushita S, Kusakabe M, 2004, Physical performance evaluation of a 256-slice CT-scanner for four-dimensional imaging, Med. Phys, 31(6): Saito Y, Aradate H, Igarashi K, Ide H, 2001, Large area 2-dimensional detector for real-time 3-dimensional CT (4D CT), Proc SPIE, 4320: Endo M, Mori S, Tsunoo T, et al, 2003, Development and performance evaluation of the first model of 4DCTscanner, IEEE Trans Nucl Sci, 50: Mori S, Obata T, Kishimoto R, Kato H, Murase K, Fujiwara H, Kandatsu S, Tanada S, Tsujii H, Endo M, 2005, Clinical Potentials for Dynamic Contrast-Enhanced Hepatic Volumetric Cine Imaging with the Prototype 256-MDCT Scanner, Am J Roentgenol, 185(1): Mori S, Endo M, Obata T, Murase K, Fujiwara H, Susumu K, Tanada S, 2005, Clinical Potentials of the Prototype 256-Detector Row CT-Scanner, Acad Radiol, 12(2): Funabashi N, Yoshida K, Tadokoro H, Nakagawa K, Komiyama N, Odaka K, Tsunoo T, Mori S, Tanada S, Endo M, Komuro I, 2005 Cardiovascular Circulation and Hepatic Perfusion of Pigs in 4-Dimensional Films Evaluated by 256-Slice Cone-Beam Computed Tomography, Circ J, 69(5): Kondo C, Mori S, Endo M, Kusakabe K, Suzuki N, Hattori A, Kusakabe M, 2005, Real-Time Volumetric Imaging Of Human Heart Without Electrocardiographic Gating by 256-Detector Row Computed Tomography, J Comput Assist Tomogr, 29(5): Taguchi K, 2003, Temporal resolution and the evaluation of candidate algorithms for four-dimensional CT, Med. Phys. 30(4): Zamyatin A, Taguchi K, Silver M, 2005, Experimental Reconstruction Algorithm for 256-slice Cone-beam Helical CT, Present The research and development of 4D-CT is performed in cooperation with NEDO, Japan (New Energy & Industrial Technology Development Organization) and the National Institute of Radiological Sciences, Japan. 256 Detector image courtesy of: National Institute of Radiological Sciences, Tokyo Women s Medical University, Jikei University School of Medicine, University of Fukui. A publication produced by Toshiba Medical Systems February 2006

10 How Effective is Cardiac CT? Physicians Speak Out GUEST SPEAKERS Gerald M. Burma, MD, PhD Cardiologist, Cardiovascular Clinic at Parma, Ohio Peter S. Fail, MD Director of Cardiac Catheterization Lab and Interventional Research, Cardiovascular Institute of the South INTRODUCTION: We asked physicians for their views on 64-detector cardiac CT technology in routine practice and how cardiac imaging might be advanced in the future. Steven R. Gunberg, DO Diversified Radiology of Colorado, P.C. Clinical Assistant Professor, University of Colorado Health Sciences Center Bruce S. Lachterman, MD Medical Director for the Cardiac Catheterization Laboratories at Houston Northwest Medical Center and St. Luke s Community Medical Center, The Woodlands Ron M. Peshock, MD, PhD Professor of Radiology and Internal Medicine and Assistant Dean for Informatics, University of Texas Southwestern Medical Center at Dallas Recent statistics indicate that more than 300,000 Americans annually suffer from heart disease, with their first symptom being a heart attack or even sudden death. How do you think cardiac CT will impact these patients? Dr. Lachterman: Cardiac CT will have an enormous impact on those patients with undiagnosed coronary artery disease. With the ability to detect diseases beyond coronary artery stenosis, which is what other modalities normally detect, we now have the opportunity to detect cardiac disease at an early stage to treat and prevent a broader spectrum of cardiovascular events. Cardiac CT is a breakthrough technology, and I believe it will become the gold standard for cardiac disease detection. Dr. Burma: I agree, and calcium scoring will also play a significant role in identifying patients with high-risk coronary artery disease. While screening will not identify disease in all patients, it may prove effective in 75 percent of the at-risk population. A certain percentage will seek medical intervention, but at least those patients will be made aware of their disease and its symptoms, potentially leading to early treatment. 10 February 2006 A publication produced by Toshiba Medical Systems

11 Stented LAD with neointimal hyperplasia. Cardiac Function Analysis. Dr. Gunberg: Certainly the impact of cardiac CT cannot be underemphasized. With this new technology, we can rapidly conduct cardiac procedures and triage patients more quickly to assess low probability or indeterminate probability for a cardiac event. Dr. Peshock: Identifying at-risk patients and preventing problems in those who don t present symptoms prior to death or their first attack, is obviously vital. It s important to point out the potential role that cardiac CT could play here. There are a number of clinical studies on the horizon that may clarify the role of cardiac CT in addressing these types of patients. How important is the ability to accurately visualize the vessel wall and characterize plaque? Dr. Fail: This is an important clinical benefit because if we can image arteries before they reach 50 percent blockage, we can be fairly comfortable that the vessel wall will not rupture and be less concerned about patients with thin, fibrous plaque or what looks to be a vulnerable lesion. Cardiac CTs may help us image noninvasively, with a high degree of accuracy, from 50 to 60 percent blockage of vulnerable plaque that has a chance of rupturing which may not be angiographically impressive, but is histologically impressive. We may be able to intervene early with a drug-eluting stent much more aggressively to prevent the plaque from rupturing and endangering the life of the patient. Dr. Burma: It s very important to identify calcified plaque as well as soft plaque. Higher soft plaque burden, as opposed to calcified plaque burden, correlates to a higher risk and adverse event rate. In the near future, we might see the development of a cardiac CT with algorithms able to assess the amount of soft plaque that is visible through CT angiography. Dr. Gunberg: I concur. The 64- detector cardiac CT enables us to visualize evolving plaque, or plaque considered vulnerable, far more easily than conventional coronary angiography. We re also able to see changes in the coronary vessels during the procedure and follow those changes much more accurately than before. What role will calcium scoring ultimately play as a risk factor in coronary artery disease? Dr. Burma: From my perspective, cardiac CT will become the mammogram of cardiology. A publication produced by Toshiba Medical Systems February

12 H o w E f f e c t i v e i s C a r d i a c C T Therefore, it is very important to have a mechanism in place for reading these studies. In many cases, the mechanism should involve a radiologist. The second point is to realize that when there are other findings beyond coronary anomalies in the heart, the patient might have significant valvular disease or other important findings. Dr. Fail: We all recognize that coronary artery disease continues to be the number one killer so, as we perform more CTAs on a routine basis and discover incidental findings, it gives us more and more opportunity to intervene and to positively impact the patient s life. Chest pain triage protocol to rule out a coronary event, PE or aortic dissection. Dr. Peshock: Calcium scoring has What are the implications when undergone quite an evolution over there are incidental findings of the last several years, but there are other disorders outside studies coming out now that point to the heart? significant value in calcium scoring. Dr. Burma: The implications are significant for cardiologists, because Dr. Gunberg: Calcium scoring will in 25 percent of the cases, we re seeing be an ideal screening test for patients in nodules and other incidental findings. lower risk situations or those patients In one recent instance we actually interested in determining their heart detected breast cancer on a patient condition. However, my feeling is during a routine cardiac CT exam. In that while calcium scoring is a useful our first 500 cardiac CT cases, we clinical tool, a coronary CT angiogram detected five lung cancer cases. This using the same 64-detector cardiac leads to an interesting issue: the use of CT offers far more comprehensive 64-detector CT technology to screen for diagnostic benefits. lung cancer. In each case, it s crucial to detect disease at the earliest stage. Dr. Lachterman: In my opinion, coronary artery calcium scoring will Dr. Peshock: In my view, there are become another form of secondary risk two important points here. First, there factor that will add to our diagnostic will be incidental findings. I ve seen capabilities when evaluating patients for supporting data to suggest that if we re cardiac disease. I don t believe it s going evaluating patients with chest pains, to be a primary risk factor nor a test for we ll find more cases of incidental detecting cardiac disease. findings than in screening studies. Dr. Gunberg: In our practice, radiologists and cardiologists are collaborating to ultimately benefit the patient. This is key because there are so many minute caveats impacting coronary artery disease, as well as in visualizing the lungs or even the liver. Given the complexity of imaging the human body, cardiologists and radiologists should be required to collaborate to provide patients with the best possible care. With collaboration, radiologists and cardiologists can not only provide better patient care, they can also take the next leap forward in cardiovascular medicine. How will radiology and cardiology professionals work together, if at all, using 64- detector cardiac CT? Dr. Burma: I think it is essential for radiology and cardiology departments to work together to develop a successful program. All cardiac CT studies should be reviewed jointly by cardiologists and radiologists to ensure that the studies are properly interpreted. We obtain an enormous amount of data 12 February 2006 A publication produced by Toshiba Medical Systems

13 H o w E f f e c t i v e i s C a r d i a c C T from a cardiac CT, and it goes without saying that we can t ignore incidental but potentially vital findings simply because they reside outside the heart. Dr. Fail: With a cardiac CT scan, we re capturing a huge amount of data that we ve never seen from an angiographic standpoint. A cardiologist may look at the intra-luminal aspects of vessels, whether coronary or peripheral, but they don t necessarily look at the whole anatomy. Cardiologists may not be as well equipped to understand all the subtle nuances of CT scans that a radiologist might, therefore, it s important to develop a partnership between two different medical specialties that come together for mutual benefit. Dr. Lachterman: I expect this new technology will encourage a more collaborative working relationship between radiology and cardiovascular imaging professionals. That is the way we conduct procedures at our facility, with both cardiology and radiology staffs providing input. What are some clinical uses for cardiac CT other than coronary imaging? Dr. Burma: In patients with dilated cardiomyopathy documented by echocardiography, especially those cases in which ejection fraction is very low for unknown reasons, a cardiac CT exam can be very helpful. It helps us to determine the etiology and whether the coronaries are normal or abnormal due to coronary artery disease. CABG follow up. Cardiac CT does a great job of clearly imaging the treatment area. We also can visualize valves more clearly, as well as ejection fraction and wall motion. All of these procedures, previously performed with ultrasound, have been improved using 64-detector cardiac CT. Dr. Lachterman: Functional analysis, ejection fraction and visualization of regional wall motion are essential elements of cardiac study interpretation and an important advent of 64-detector cardiac CT technology. Utilizing this technology for detecting congenital heart disease also contributes to imaging the coronary artery anatomy. What is the role of 64-detector CT in procedures such as cardiac catheterization follow-ups? Dr. Fail: What the cardiac CT enables us to do is identify patients without advanced heart disease, who can manage the disease by modifying the risk factors, without exposing them to the risk of cardiac cath. For patients with peripheral vascular disease or abdominal aortic inclusions, all followup procedures are performed at our practice with CT. For patients with anomalous coronary arteries that are difficult to reach using cardiac cath, CTA does a beautiful job of visualizing the aorta and the appropriate avenue for performing a comprehensive study. Dr. Burma: Another example in which cardiac CT will be valuable in follow-up is with stent and bypass surgery patients. We ve also been able to identify graft disease and visualize lesions, which frequently are not calcified. These procedures may be questionable for patients with little or no symptoms, but cardiac CT could vastly improve follow-up for bypass patients after seven or eight years. CA Dr. Fail: One of the new and exciting medical technologies still in research is visualizing the left atrial appendage occluder something that basically puts a plug in the left atrial appendage. Plaque imaging using Toshiba s clinically validated SURE Plaque software. A publication produced by Toshiba Medical Systems February

14 Aquilion 64 Case Study Incidental Finding of Metastatic Lesion profile: 71-year-old female with a history of small cell lung cancer. Coronary CTA showed no vessel disease. Left ventricular septal wall images reveal a hyper vascular mass suspicious of a metastatic lesion. FINDINGS: Left ventricular septal mass. Scan parameters: 0.5mm x s/R acquired in 8 seconds at a range of 118mm. Image 1: 3D VR shows the left main, LAD and circumflex arteries. Image 2: Slab maximum intensity projection in a 4 chamber view shows the left ventricular mass. Image 3: 5mm, MIP projection in the short axis plane shows the extent of the mass. Image 4: Incidental finding of a possible metastatic lesion seen on Coronary CTA. 14 February 2006 A publication produced by Toshiba Medical Systems

15 Aquilion 64 Case Study Coronary CTA: Anomalous Left Coronary Artery profile: 51-year-old man referred for a coronary CTA. Patient has a strong family history of heart disease and increased LDL. FINDINGS: 3D volume, curved MPR and MIP renderings were reviewed. An anomalous left coronary artery rises from the RCA. The LAD travels anterior to the pulmonary outflow tract. There is a branch from the RCA that traverses between the aortic outflow tract and the pulmonary outflow tract and ending in the left ventricular septal wall. Dominant RCA shows mild peripheral calcified plaque. The RCA supplies a large PDA with multiple posterior lateral ventricular branches. Scan parameters: 120kV, 380mA, 0.5mm x 64-slice. Scan time of 7.5 seconds. Image 1: 3D volume rendered image of the anomalous LAD traveling anterior to the pulmonary out flow tract. Image 2: Posterior volume rendered view of the anomalous LAD origin and dominant RCA is clearly visualized. Image 3: Curved MPR of the RCA mild calcified plaque is visible in the proximal and mid vessel. Image 4: Curved MPR shows the anomalous LAD. Image 5: Four-chamber long axis MIP projection of the RCA branch traversing between the aortic and pulmonary outflow tracts. A publication produced by Toshiba Medical Systems February

16 Characterizing Vulnerable Plaque Excerpts from Narula et al. J Am Coll Cardiol 2005; 45: More than 13 million subjects suffer from coronary artery disease in the United States alone and a large number of patients develop acute coronary events. Over 1.1 million patients present with acute myocardial infarction every year, about 150,000 new cases of unstable angina are diagnosed and 450,000 die suddenly as the first manifestation of the atherosclerotic process. In spite of tremendous advances in the management of coronary disease, we have been unable to clinically identify patients who would sustain acute coronary events. Although it is feasible to identify vulnerable patients by virtue of various biomarkers, it will be of utmost importance that we identify plaques that are likely to lead to acute events. Such a strategy would allow prevention of acute events. For such a strategy to be successful, we would need to move away from the focus on luminal occlusion only and identify the morphological characteristics of atherosclerotic plaques. Our current management strategy is based on the demonstration of critical luminal obstruction, which is able to identify the extent of symptomatic disease, but is not able to identify the prognostic nature of the plaque. As such, to be able to develop prevention-based management algorithms, we will need to pay divided attention to both the lumen and the vessel wall. The advent of high resolution multi-slice computed tomographic (MSCT) imaging has, for the first time, allowed characterization of the 16 February 2006 A publication produced by Toshiba Medical Systems

17 PLAQUE VOLUME AND NECROTIC CORE Plaque volume > 50% Positive Remodeling Characteristics of vulnerable plaque (courtesy of J. Narula, MD) composition of the plaques. MSCT is capable of detection of the large necrotic core, which is becoming established as the sine qua non of plaque vulnerability. The larger the plaque volume and necrotic core, the higher the likelihood of plaque rupture. Recent investigations using MSCT have demonstrated that hypodense areas in the plaques can be equated with the necrotic lipid cores, or so-called soft plaques. Pathologic Substrates for Imaging Vulnerable Plaque Plaque rupture is responsible for up to three-fourths of the victims of acute coronary events. The rupture of the fibrous cap of the atherosclerotic plaque exposes the thrombogenic core to the luminal blood and leads to acute thrombosis. Ruptured plaques invariably demonstrate a sizable necrotic core and their thin (ruptured) fibrous cap is intensely infiltrated by foamy macrophages. The plaques that are vulnerable to rupture are likely to harbor the same histopathologic signatures, except that the thin cap has not yet broken. Further, the necrotic core in the ruptured lesions is significantly larger than the intact vulnerable plaques, substantiating that the progressive enlargement of the necrotic core is associated with vulnerability to rupture. Enormity of Plaque Volume and the Size of Necrotic Cores Cardiologists have traditionally believed that the plaques that rupture are minimally occlusive. This belief is based on the angiographic characterization of the vessels in A publication produced by Toshiba Medical Systems February

18 C h a r a c t e r i z i n g V u l n e r a b l e P l a q u e patients presenting with acute coronary syndromes, cores in ruptured and vulnerable plaques are often large which demonstrated that up to 66% of patients with and measure 2-22mm in length; the average longitudinal unstable angina, and 50% of those presenting with extent is 9mm. Necrotic cores associated with ruptured acute myocardial infarction, had angiographic luminal plaques occupy more than 60º circumferential stenosis of less than 50%. However, involvement of the vessel. the pathologic characterization of coronary lesions in the victims of Evolution of the Necrotic Core acute coronary syndrome reveal that two-thirds of vulnerable plaques are >50% and one-quarter are >75% cross-sectionally occlusive, whereas three-quarters of ruptured plaques are >50% and one-half are >75% stenotic. Less than 50% cross sectional narrowing is observed only in less than 20% of ruptured plaques. The reason for the discrepancy between the angiographic and pathologic data can be explained by Progressive enlargement of the necrotic core is associated with vulnerability to rupture During the evolution of atherosclerotic plaque, the ongoing death of macrophages contributes to the formation of a necrotic core. Worsening hypoxia in the necrotic core, on one hand, adds to the necrotic death and enlargement of the necrotic core, and on the other hand promotes neovascularization. These nascent vessels are inherently leaky and allow extravasation of red blood cells (RBC) into the the expansive outward remodeling of the vessel, which plaque. It is well appreciated that the cholesterol content prevents apparent luminal narrowing. Positive remodeling of erythrocyte membranes exceeds that of all other cells is not seen in stable plaques which have diminutive in the body, with lipid constituting 40% of the weight, necrotic cores and more fibrotic contents. and may contribute to the cholesterol pool of the necrotic In addition to actual plaque volume, the magnitude core. Intraplaque hemorrhages due to the rupture of these of the necrotic core in a given plaque needs to exceed immature vessels may contribute to the accumulation a critical threshold to render the plaque vulnerable to of a large number of RBCs and hence cholesterol. It has rupture. It occupies more than 25% of the plaque area in been tacitly proposed for many decades that intraplaque more than two-thirds of disrupted plaques. The necrotic hemorrhage is a major contributor to the progression of Axial view of the proximal LAD which has low HU suggestive of soft plaque. Same plaque in CMPR view of proximal LAD. 18 February 2006 A publication produced by Toshiba Medical Systems

19 C h a r a c t e r i z i n g V u l n e r a b l e P l a q u e LAD with atherosclerotic plaque and positive remodeling. coronary atherosclerosis. We have observed that plaque hemorrhages are more common in the coronary arteries in patients dying from rupture, compared with stable lesions as detected by glycophorin A (a protein exclusively associated with RBC membrane). The degree of reactive glycophorin A staining and the level of iron deposits in the plaque was directly proportional to the size of the necrotic core, and the macrophage density. 1 By contributing to the deposition of free cholesterol, enlargement of the necrotic core and macrophage infiltration, the RBC build up within neointima may render plaques unstable. Circulating hyperlipidemia contributes to RBC accumulation in the neointimal microenvironment. First, the number of vasa vasorum is increased 2-fold in vulnerable and 4-fold in disrupted plaques compared to stable plaques with severe luminal narrowing. Microvessels that perforate from the adventitial layer to the medial layer are well formed because they are enveloped by smooth muscle cell (SMC), unlike neointima where they appear immature and leaky. It is plausible A publication produced by Toshiba Medical Systems February

20 C h a r a c t e r i z i n g V u l n e r a b l e P l a q u e that abundant T helper cells found at the medial wall coronary arteries and such plaques are only rarely seen in perforation points may inhibit SMC proliferation the distal vessels. through interferon 7-gamma, contributing to medial disruption and absence of SMC. The extent of vasa Ability to Image Vulnerable Plaques and the vasorum correlated with intimal macrophage content Role of MSCT in Plaque Detection and with previous cardiovascular Since vulnerable plaques occur in a events. Extensive experimental proof patient only in very small numbers, is available to this effect, as the they often have large dimensions density of vasa vasorum (measured by and are located in relatively micro-ct) increases markedly during hypercholesterolemia and resolves with statins. The increase in vasa vasorum is associated with vascular endothelial growth factor expression in the neointima and neoangiogenesis. Interestingly, the internal mammary artery, a vessel with low incidence of atherosclerosis, shows significantly low vasa vasorum density. Positive remodeling is not seen in stable plaques proximal parts of the major coronary trunks. It is expected that they should be easily identifiable by appropriate imaging techniques. Intravascular ultrasound (IVUS) of patients presenting with acute coronary syndromes demonstrates positive vascular remodeling and plaques containing relatively signalfree necrotic cores. IVUS imaging In addition to hypercholesterolemia-induced of coronary arteries in 200 patients often demonstrated vasa vasorum proliferation, erythrocyte membranederived cholesterol is elevated in patients with of the infarct-related vessel occurred in two-thirds of actual plaque rupture sites, and that plaque rupture hypercholesterolemia and is sensitive to short-term statin patients presenting with acute myocardial infarction. It therapy. Because RBCs are not capable of synthesizing was therefore proposed that intact plaques with similar lipids de novo, most of the membrane lipid content findings should be deemed vulnerable. Such presumption originates from an exchange with plasma lipoproteins. has been validated by serial observations in a two-year The excess membrane cholesterol leads to crystalline follow-up of 100+ patients. The lesions which lead to an cholesterol deposition in necrotic cores as the RBC acute coronary event over time were characteristically undergo crenation. In addition to leaky vasa vasorum, large, containing prominent and shallow echolucent plaque fissuring can also account for the accumulation of zones. erythrocytes, which has also been described to occur in The features of non-triviality, large necrotic cores the coronary vasculature of patients dying from sudden and outward remodeling should be identifiable by MSCT. coronary death. Density-based software should be able to mechanically define the plaque characteristics and identify the Number and Location of Vulnerable Plaques necrotic cores. The best available low-contrast, highresolution and minimum available slice thickness (such Although the presence of risk factors render the patients vulnerable to acute coronary syndromes, it is becoming as 64x0.5mm) capability of the hardware should allow increasingly clear that only 1-3 vulnerable plaques may better differentiation of the fibrous from soft plaques. be seen in an individual presenting with acute coronary It is imperative that the ultimate technology allow syndromes. Pathologically, vulnerability of a plaque this differentiation, rather than a simple distinction of is a very discrete and localized phenomenon and the calcified from non-calcified lesions. Arterial remodeling of perceived instability in an artery as a whole is an unlikely the vessel wall is the most important marker that can set phenomenon. Further, more than 95% of vulnerable the MSCT apart from angiography since the vessel wall lesions are confined to the proximal or middle parts of the can be easily observed. CA Excerpts from Picking Plaques That Pop... Narula J, Finn A, DeMaria A, J Am Coll Cardiol 2005; 45: February 2006 A publication produced by Toshiba Medical Systems

21 Aquilion 64 Case Study Coronary CTA: Multiple Mixed Plaques profile: 62-year-old male presented with complaint of chest tightness and pain during rest. Coronary CTA performed. FINDINGS: Curved MPR, MIP and 3D volume rendered images were reviewed. The left main coronary artery is normal in caliber with no visible plaque. There is a densely calcified plaque in the LAD causing mild narrowing. The first diagonal also has a calcified plaque with minimal stenosis. Mild soft plaque is present throughout the proximal and mid circumflex. There is a focal soft plaque in the proximal right coronary artery causing a 50% stenosis. Irregular soft and hard plaques are present in the mid RCA with a 30-40% stenosis. Scan parameters: 120kV, 400mA, 0.5mm x 64-slice. Scan time of 8 seconds with 13cm coverage. Image 1: 3D vessel tree with multiple calcified plaques in the LAD, circumflex and RCA. Image 2: 3D volume with vessel probe CMPR images. There is a large calcified plaque in the proximal LAD with mild narrowing of the lumen. Image 3: Curved MPR views with multiple soft and calcified plaques along the RCA and LAD. Image 4: 3D Volume rendered MIP image. A focal soft plaque is seen in the proximal vessel along with multiple calcified lesions. Image 5: Transparent background rendering of the myocardium clearly displays the anatomical relationship of the coronary vessel tree. Image 6: 3D angio emulation view of the coronary tree. A publication produced by Toshiba Medical Systems February

22 Practical Matters Education and Reimbursement GUEST SPEAKERS Gerald M. Burma, MD, PhD Cardiologist, Cardiovascular Clinic at Parma, Ohio Peter S. Fail, MD Director of Cardiac Catheterization Lab and Interventional Research, Cardiovascular Institute of the South Steven R. Gunberg, DO Diversified Radiology of Colorado, P.C. Clinical Assistant Professor, University of Colorado Health Sciences Center INTRODUCTION: The guidelines set forth by the American College of Cardiology and the American College of Radiology for cardiac CT imaging have spurred a new debate on the best approach for implementing this revolutionary technology in clinical practice. We asked several physicians for their views in a roundtable discussion. Bruce S. Lachterman, MD Medical Director for the Cardiac Catheterization Laboratories at Houston Northwest Medical Center and St. Luke s Community Medical Center, The Woodlands Ron M. Peshock, MD, PhD Professor of Radiology and Internal Medicine and Assistant Dean for Informatics, University of Texas Southwestern Medical Center at Dallas What does today s 64-detector cardiac CT allow physicians to do that they couldn t do in the past? Dr. Lachterman: With 64-detector cardiac CT, we have gained a much better understanding of the heart by being able to image not only the cardiac structures, but also the cardiac vessels. This can be performed on CT systems with less than 64 detectors, but not to the same extent. Today s advanced 64-detector cardiac CT allows much shorter scan time, which is crucial for imaging the beating heart. Dr. Burma: The use of 64-detector CT has affected three areas in cardiac care. First, calcium scoring using cardiac CT has become an extremely important test for screening the population for coronary artery disease. Calcium scoring enables us to determine those patients that need treatment, and those that don t because they are at such a low risk of cardiac event. The second use is coronary CT angiography. In our practice, we re using CT on patients with equivocal stress tests who are demonstrating low to intermediate risk, as well as those with unexplained chest pains with intermediate risk. The third use is for cardiac CT scanning as chest pain triage for emergency rotation and the diagnosis of peripheral vascular disease. Dr. Peshock: As a cardiologist by training, what attracted me most to the fast multi-detector CT with gating was the low-contrast performance and the ability to do rapid assessment of the coronary arteries in a variety of patients. 22 February 2006 A publication produced by Toshiba Medical Systems

23 What will be required to secure adequate, Dr. Burma: The other area that needs to be addressed consistent reimbursement for the is the role of cardiac CT on the reduction of healthcare professional and technical components costs. At our practice, we are investigating the economic of cardiac CT studies? impact carefully with our first 500 patients. Specifically, Dr. Peshock: I believe that the multi-center trial (CorE we re measuring the cost difference between patients who 64) that Toshiba is sponsoring is ordinarily elect to have a cardiac absolutely critical to moving us forward cath, priced anywhere from $5,000 in addressing the reimbursement issue. to $6,000, and those opting for The critical piece of information is the correlates more specifically, absolute cath invasive correlates for the cardiac CT studies. The result is cardiac CTobtained data that is reliable and robust enough to convince those responsible for reimbursement that 64-detector cardiac CT is a definitive approach to assessing the coronary arteries. The CorE 64 multi-center trial will be the crux of the reimbursement issue cardiac CT angiography, which costs approximately $500. How will the 64-detector CT multi-center trial affect the validation and reimbursement of CT angiography? Dr. Burma: It s going to be meaningful for those third parties who require a significant level of data Dr. Fail: It will be important to demonstrate the impact of to determine cardiac CT exam reimbursement. While some 64-detector cardiac CTs on patients. Hopefully, Centers for smaller third parties may not be convinced, I certainly think Medicare and Medicaid Services and insurance companies the data will be helpful in moving us forward. will realize the benefits of impacting patients at an early stage with medications which should result in lower costs Dr. Fail: To reiterate, a multi-center trial will be an through more infrequent use of angiograms, stenting or important step toward validating the use of 64-detector bypass surgery. cardiac CTs. With that said, my concern with CTAs versus conventional angiograms is that they are two distinct studies. In a CTA, we re visualizing the vessel, its walls, the thickness of the wall, and the lumen we re able to look at almost everything whereas in an angiogram, we re looking at the true luminal diameter. In turn, we re taking a less sophisticated test to validate a more sophisticated test, which, unfortunately, is how a validation study typically works. Ultimately, the goal for us through research, like the CorE 64, is to make CTAs the gold standard in detecting heart disease. Dr. Gunberg: From my point of view, the CorE 64 multi-center trial will be the crux of the reimbursement issue. Once these trials are completed and prove to those responsible for reimbursement the importance of imaging coronary artery disease, they might very well decide the future role of cardiac CTs in medicine. The CorE 64 multi-center trial will provide clinically important correlation between catheter angiography and cardiac CTA. Given the lack of formal, post-training education on the diagnostic capabilities of 64-detector cardiac CT, how should the new guidelines for using this clinical tool evolve? Dr. Peshock: The existing guidelines have been A publication produced by Toshiba Medical Systems February

24 P r a c t i c a l M a t t e r s 3D volume rendering. Volume rendered tricuspid valve. thoughtfully prepared because these new technologies written primarily for academia without consideration of the require radiologists and cardiologists to acquire new skills many cardiac CT studies that have already been performed in all cases. I think we ll see a dramatic increase in the in private practices. This needs to be addressed as the number of educational opportunities in these areas over guidelines evolve. the next several years. To successfully perform these studies, it s important that radiologists and cardiologist Dr. Fail: With the explosion of multi-slice CT technology have exposure to a wide range of studies. What is needed in the cardiology arena, the technology has outpaced many is greater expertise in the details of practitioners ability to understand its the individual imaging techniques, as clinical benefits. From an educational well as increased familiarity with the standpoint, there are numerous occurring artifacts. textbooks and training programs Dr. Lachterman: Cardiac CT is a new and evolving technology and most physicians practicing today have very minimal experience, if any, with this modality in clinical applications. Some of the training programs available do not offer the same formal training in cardiac CT imaging as they do in nuclear medicine, echocardiography or Learning to properly apply the new technology may be the biggest challenge offered by vendors covering CT angiography (CTA), but it s difficult to expect cardiologists to learn all the subtle nuances of reading a CTA in just a week it s not that simple. Even after two years, I am still in the process of learning how to read and interpret CTAs. Guidelines are premature but they will help us in the future to conduct better cardiac CT exams. invasive cardiology. The guidelines have to include didactic training, at least to a limited degree, so physicians can gain How will the new guidelines and the increasingly first-hand experience in reading cardiac CT studies. Clearly, difficult credentialing requirements impact these guidelines must constantly evolve with the technology. physicians? Dr. Peshock: I think the guidelines are crucial to assure Dr. Burma: In my opinion, the guidelines have been the highest level of expertise in both acquisition and 24 February 2006 A publication produced by Toshiba Medical Systems

25 P r a c t i c a l M a t t e r s interpretation. My personal thought is that physicians properly apply the new technology may be the who are sincerely interested in pursuing this field will biggest challenge. need to dedicate significant time to it. I don t think this will be particularly onerous but, on the other hand, it s Dr. Lachterman: Initially, this will not be much of important to devote sufficient time and energy to master a burden because there are no definitive guidelines or the technology. credentialing requirements yet and the current requirements are lenient. Dr. Fail: Unfortunately, there will be some physicians who are going to be left behind. A lot of cardiologists who have experience with traditional angiograms expect CTAs to be the same, and that s just not the case. CTAs are an entirely different study that is more complex, with subtle nuances that require more time to read and interpret. Guidelines may require physicians to not only prove that they can read a CTA properly, but also perform advanced procedures beyond CTA. Dr. Gunberg: Since many of the advances in cardiac CT imaging are driven by technology, I don t think the guidelines and credentialing requirements will be as burdensome as some might assume. However, learning to Unfortunately, there will be some physicians who are going to be left behind However, in the near future, as the technology evolves and formal training guidelines are developed, the new guidelines could prove burdensome to physicians because formal training will take time out of their practice. How will cardiac CT education affect the routine practice of cardiology and the use of this evolving clinical tool? Dr. Burma: If the educational requirements are stringent, such as a mandatory six months of formal training, they could become a hurdle to further technological development. While I don t think the requirements will ultimately be this stringent, I do anticipate at least a one-week formal training course. There is also the issue of physicians needing to be grandfathered into the process, which needs to be addressed. Dr. Fail: At the physician level, we re still learning. There are still many small practices that do not have a CT scanner to perform routine imaging or access to a more advanced 64-detector cardiac CT although, I think this is changing. It s a similar situation when you consider sophisticated PET scanning for coronary artery disease and MRI scanning, where more advanced modalities are available at university centers but not necessarily in private practice. However, thanks to its clinical benefits, 64-detector cardiac CTs will eventually become more routine in private practice settings. 3D volume rendering of multiple vessel disease. Dr. Peshock: I think we all agree that the 64-detector cardiac CT is a new and exciting technology requiring supplemental education of referring clinicians. As clinical studies point to the best indication for this technology, we have to educate internists, as well as interventional and diagnostic cardiologists, to help them understand how to apply this technology wisely. CA A publication produced by Toshiba Medical Systems February

26 Aquilion 64 Case Study Coronary CTA: Stent Follow-up profile: 68-year-old male presented with complaint of increasing chest pain and discomfort. Coronary CTA performed. Follow-up post stenting of the RCA, LAD and circumflex arteries. FINDINGS: The left main coronary is normal. There is a stent in the proximal LAD. Just proximal to the stent there is a low signal intensity soft plaque, suspicious for a lipid rich lesion. Also noted is a calcified lesion in the same area. The stent in the circumflex artery is patent with no visible stenosis. Two stents are visible in the proximal to mid RCA. In the distal stent, there is low signal intensity in the lumen, suspicious for neo-intimal hyperplasia. Scan parameters: 120kV, 350mA, 0.5mm x 64-slice. Scan time of 8 seconds. Image 1: 3D volume rendered vessel tree with transparent myocardium. Stents are visible in the LAD, RCA and circumflex. Image 2: Curved MPR view of the RCA showing multiple stents. There is low signal intensity in the mid portion that represents neo-intimal hyperplasia. Image 3: Curved MPR of the stent placed in the proximal LAD. Note the low intensity soft plaque lesion just proximal to the stent. Image 4: Curved MPR of the stent placed in the circumflex vessel. Good flow is seen through this patent stent. Image 5: Posterior 3D volume view of the distal portion of the RCA stent and PDAs. 26 February 2006 A publication produced by Toshiba Medical Systems

27 Aquilion 64 Case Study Coronary CTA: Multiple Vessel Disease profile: 40-year-old female with history of hypertension states she has pain and discomfort in the left arm and shoulder during exercise. Coronary CTA performed. FINDINGS: The left main coronary artery is normal with no visible plaque or stenosis. A complex calcified and soft plaque is visible in the proximal LAD, causing a 70% narrowing. The circumflex artery is normal. The RCA is well visualized with a large soft and calcified plaque in the proximal-to-mid portion causing a 60% narrowing. Scan parameters: 120kV, 360mA, 0.5mm x 64-slice. Scan time of 9 seconds. Image 1: 3D volume rendering with vessel probe CMPR. Normal left main coronary artery is visible; LAD artery shows multiple soft and calcified plaques. Image 2: Curved MPR view rendered with single click vessel probe. Soft plaque remodeling is noted along the RCA and LAD. Image 3: Thin slab axial MIP shows normal left main and soft plaque stenosis of the proximal LAD. Image 4: Short axis MIP of the RCA easily identifies a complex soft and calcified lesion in the proximal-to-mid vessel. A publication produced by Toshiba Medical Systems February

28 DI_OUTSERT 15