With recent rapid technologic advances in multislice computed tomography (CT), cardiac CT has emerged as a promising noninvasive imaging modality for the assessment of coronary artery disease (CAD). Current-generation CT scanners can quickly and accurately identify oPstuctive coronary lesions or exclude disease in patients without known CAD. Even though large clinical trials are needed, the current indications for the assessment of CAD with cardiac CT are expanding and include the initial evaluation of chest pain in properly selected patients.
Coronary artery disease (CAD) remains the number-one cause of death in the United States; in 2003, it accounted for 1 of every 2.7 (37.3%) deaths.1 The traditional noninvasive approach to detecting CAD is stress testing. Stress testing provides physiological evidence of the hemodynamic consequences from flow-limiting stenoses through characteristic changes on the electrocardiogram, myocardial perfusion defects, or regional wall motion abnormalities.
Direct assessment of the coronary artery lumen for CAD has traditionally required invasive coronary angiography or catheterization. Catheter-based X-ray angiography is associated with significant cost, inconvenience to patients, and a small but not negligible risk of serious complications due to the inherent invasive nature of the procedure.2 From 1979 through 2003, the number of inpatient cardiac catheterizations in the United States had increased 373% to a total of 1.4 million diagnostic procedures in 2003; however, only approximately 40% were followed by an intervention.
Cardiac CT is a rapidly emerging technique for the noninvasive visualization of coronary arteries. It is an attractive alternative to invasive selective coronary angiography with the potential to reduce the number of purely diagnostic cardiac catheterizations. Electron beam CT, which was developed in the early 1990s, pioneered cardiac CT with coronary calcium assessment and initial work in coronary angiography. However, the relatively low spatial resolution (1.5- to 3-mm slice thickness) limited its applicability, especially with contrast-enhanced coronary angiography. During the past 5 years, rapid technologic advances have progressively improved the diagnostic accuracy of multidetector CT (MDCT) for the detection of CAD. Clinical application of 4-slice coronary CT angiography (CTA) was limited because of a substantial number of none valuable segments (up to 43%), limited resolution, and a long breath-hold (approximately 45 seconds).3 Multidetector CT with 16 slices has been shown to have an improved diagnostic accuracy for the detection of significant stenosis because of an increased temporal and spatial resolution, shorter breath-hold time (approximately 25 seconds) and a lower percentage of nondiagnostic segments.4" The introduction of contemporary 64-slice technology with very short image acquisition times (<12 seconds), gantry rotation times of 330 msec, and isotropic spatial resolution of 0.4 mm have further improved the diagnostic performance of cardiac CT.