Computed Tomography of the Coronary Arteries
Pim J. de Feyter, MD, PhD, and Gabriel P. Krestin, MD, PhD, eds.
208 pp. London, UK: Taylor & Francis; 2005. $85.00. ISBN 1-84184-439-X
Nearly 5 decades have passed since F. Mason Sones, MD, performed the first coronary angiogram. Despite transformative advances in the treatment of coronary atherosclerosis, this traditional procedure remains the foundation on which state-of-the-art diagnosis and management rests. Noninvasive imaging modalities such as scintigraphy and echocardiography have contributed immeasurably to the care of the patient with coronary disease, but these techniques only indirectly determine coronary patency. During the past few years, imaging methods that approach the accuracy of x-ray angiography have become increasingly available with the advent of the latest generation of MRI and multidetector/multislice CT scanners.
Although these 2 modalities use a common vocabulary, considerably more attention has been focused recently on CT, primarily because of its strikingly clear image quality. Not to be overlooked are the economic implications of CT in terms of reimbursement and control of technology. The arrival of coronary CT has opened a new front in the seemingly perpetual to and fro between the cardiology and radiology camps, with battles now being fought at the state and national regulatory levels. Coverage of coronary CT in the lay press and aggressive marketing of CT imaging technology to cardiologists and patients only serves to increase tension. A recently posted animated advertisement on The New York Times web site beckons patients to “ask their doctor” about the latest-generation CT scanners that can scan the heart in 8 to 10 seconds and provide an instant diagnosis. Widespread awareness necessitates that the general cardiologist familiarize him- or herself with this new imaging language. In fact, it is now necessary to understand the fundamentals of MRI and CT imaging to critically review the contemporary literature.
It is in this context that Drs de Feyter and Krestin have crafted an exquisitely illustrated and clearly written text entitled Computed Tomography of the Coronary Arteries. This is neither a technical manual nor an exhaustive reference text, but rather a concise overview of CT technique for the general cardiologist or non–CT-educated specialist in cardiac imaging. The text reflects the collaboration between a radiologist (Dr Krestin) and cardiologist (Dr de Feyter) from Erasmus Medical Center, Rotterdam, The Netherlands, and is representative of the importance of collaboration across specialties. Well aware of the turf wars this technology has incited, the editors note in the preface that this book would not have been written “without the faithful and friendly cooperation between cardiologists and radiologists in our institution.”
The book is organized as a comprehensive introductory text, with 20 concise chapters. The first 2 chapters cover the basic principles of CT imaging and specific relevant aspects of image processing. There is less emphasis on CT technique and more on image interpretation. This is appropriate, for in practice, CT technology has advanced to a degree that the acquisition of data is largely automated. In contrast, cardiovascular MRI (CMR), which has the potential to provide a comprehensive functional examination including coronary imaging, is more demanding at the image-acquisition stage.
The book then covers coronary imaging, beginning with normal coronary anatomy (Chapter 3) and a review of the histological basis of coronary disease with illustrations by CT (Chapter 4). Chapters 5 through 12 progress through topics systematically including stenosis/occlusion, plaque imaging, stent patency and collateral flow assessment, imaging of coronary anomalies, and bypass-graft imaging. There is also a chapter that reviews the data relevant to coronary calcification (Chapter 7) and the Agatston calcium scoring algorithm. Although a calcium score can be obtained with multidetector CT, typically, an electron-beam CT system (EBCT) is used for this test. Noncoronary applications of CT, including evaluation of cardiac masses and imaging of the great vessels, are discussed in Chapters 13 to 16. There is an invaluable review of artifacts and their manifestations (Chapter 18), beautifully illustrated in sharp, clear examples. Chapter 19, which reviews the timing techniques during the iodinated contrast bolus, seems better placed at the beginning of the book because it reviews the technical aspects of image acquisition. The text concludes with a brief discussion of left ventricular function assessment and presents the editors’ perspective on the future of coronary CT, including a few 64-slice studies.
The straightforward explanations of potentially complex concepts and striking illustrations of volume-rendered and multiplanar reconstructed images, nearly always presented with the correlative gold standard, x-ray angiography, make this an excellent foundation book. Furthermore, the crisp cartoon-like illustrations reiterate points made in the accompanying text and reinforce the concepts.
Multidetector CT technology has rapidly evolved during the past 4 years from 4- to 8- to 16- and now 64-slice devices, each capable of imaging the coronary arteries in less time. The majority of examples in this book, and in the literature, are taken with 16-slice systems. Although individual institutions with access to the newest systems (including the editors of this text) have reported high sensitivities/specificities as compared with cardiac catheterization for the detection of significant coronary stenoses, the rapid pace of change has not permitted large-scale, multicenter demonstrations of efficacy. In spite of the potential for CT to be used as a screening tool for low- to intermediate-risk patients, nearly all of the published studies have examined patients with a high clinical suspicion of coronary artery disease. Data from an intermediate-risk population for which CT may be most beneficial have yet to be reported. The editors do include a chapter entitled “The Emergency Department” (Chapter 14), which seems to suggest that coronary CT has a role in the evaluation of patients with chest pain in the emergency department; however, the chapter reviews the data supporting stratification of risk based on CT-determined calcium score and not angiography. CT angiography may prove useful in this setting and the high negative predictive value (>97%) reported with 16-slice devices does suggest that CT may be good at screening. The text presents CT angiography as a safe procedure with minimal risk as compared with x-ray angiography, and in the acute setting, this is undoubtedly true; however, a risk–benefit analysis must also include consideration of radiation exposure because with 16- and 64-slice CT, the dose may be at least 4-fold greater than diagnostic x-ray angiography. The long-term risk associated with this level of exposure, perhaps multiplied by repeats scans, is undefined.
That being said, noninvasive coronary imaging by CT is likely here to stay. Its importance to the future of cardiology is evidenced by the preparation of Core Cardiology Training Symposium (COCATS) guidelines to specify fundamental and advanced training requirements in cardiology fellowship programs. Whoever ultimately reads CT scans, and this reviewer strongly advocates a cooperative model as put forth in Computed Tomography of the Coronary Arteries, interpretation of the scan results in the context of the patient’s overall clinical presentation will be essential. The general cardiologist will need to integrate imaging information with functional stress testing. Interestingly, interventional cardiologists may receive more referrals for previously unrecognized and clinically silent stenoses. Although we are potentially nearing a time when a patient’s coronary anatomy can be defined in <10 seconds, we as cardiologists will need to understand the applications and limitations of CT techniques. Computed Tomography of the Coronary Arteries is a concise and easy-to-follow overview of the relevant concepts of CT coronary angiography. The authors and editors should be commended for producing this exceptional introduction to a complex yet promising technique.