CONTINUING EDUCATION

Coronary CT *

Udo Hoffmann1,2, Maros Ferencik1, Ricardo C. Cury1, and Antonio J. Pena1

1Department of , Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts; and 2Harvard School of Public Health, Boston Massachusetts

examinations, including patient preparation, image acqui- Advances in multidetector CT (MDCT) technology with sub- sition, and evaluation techniques. In addition, the potential millimeter slice collimation and high temporal resolution permit clinical applications and limitations of the technique are contrast-enhanced imaging of and coronary discussed. plaque during a single breath hold. Appropriate patient prepara- tion, detailed technical and technological knowledge with regard to recognition of typical imaging artifacts (such as beam harden- PATIENT PREPARATION ing or motion artifacts), and the adequate choice of postprocess- High-quality source images are the most important pre- ing techniques to detect stenosis and plaque are prerequisites to requisite for the diagnostic assessment of coronary CTA. achieving diagnostic image quality. A growing number of studies have suggested that 64-slice coronary CT angiography is highly Image quality must be ensured through multiple steps, in- accurate for the exclusion of significant coronary artery stenosis cluding patient preparation, the actual coronary CTA scan (.50% luminal narrowing), with negative predictive values of protocol, and the synchronization of raw image data with 97%–100%, in comparison with invasive selective coronary an- (ECG) information, which enables the giography. In addition, several studies have indicated that MDCT reconstruction of axial ECG-gated images. Because the also can detect calcified and noncalcified coronary atheroscle- injection of iodinated contrast material is necessary to visu- rotic plaques, especially in proximal vessel segments, showing alize the coronary artery lumen, coronary CTA is absolutely a good correlation with intracoronary ultrasound. Studies on clin- ical utility, cost, and cost-effectiveness are now warranted to contraindicated in some subjects. Relative contraindications demonstrate whether and how this technique can change and exist with respect to conditions that are known to limit diag- improve the current management of patients with suspected or nostic image quality. Table 1 summarizes absolute and rela- confirmed . tive contraindications. Key Words: coronary CT angiography; coronary MDCT; coro- nary artery stenosis; Premedication J Nucl Med 2006; 47:797–806 The image quality of coronary CTA is substantially improved in patients with a rate of less than 65 beats per minute. Motion artifacts observed in patients with higher heart rates contribute substantially to the degrada- tion of image quality. Multiple studies have demonstrated ver the last five years a dramatic improvement in multi- O that the highest image quality of coronary CTA for current detector CT (MDCT) technology has occurred. The ability generations of 16- and 64-slice MDCT scanners can be to noninvasively image the coronary artery lumen and wall achieved at low heart rates (,65 beats per minute) (1–3). and obtain information on the presence, severity, and char- Recent investigations have demonstrated that heart rate is acteristics of coronary artery disease (CAD), including the decreased by approximately 6 beats per minute as a result visualization of luminal obstruction and atherosclerotic of the inspirational breath hold only (4). Therefore, aggres- plaque, constitutes an attractive addition to currently avail- sively reducing a patient’s hea