Clinical use of multi-slice CT coronary angiography

As compared to conventional CT scanners, multi-slice spiral CT (MSCT) has improved temporal and spatial resolution. Dedicated image reconstruction algorithms permit to create cross-sectional images with a temporal resolution of approximately 150-250 ms, and a slice thickness of 0.75-1.3 mm (see Figure 1). In addition, image reconstruction can be synchronized to the ECG. This permits to use MSCT for visualization of the coronary artery lumen and detection of stenosis (see Figures 2 and 3). Various post-processing techniques can be used to display the coronary arteries. A low heart rate has been identified as an important prerequisite to obtain a sufficiently high image quality, and most authors recommend routine use of beta blocker premedication. Comparisons Of 4-slice MSCT to invasive angiography concerning the detection of hemodynamically relevant coronary artery stenoses have resulted in sensitivities ranging from 72-93% and specificities ranging from 84-98%. However, up to 32% of all coronary segments had to be excluded from evaluation due to impaired image quality, in most cases due to severe calcification or insufficient suppression of motion artifacts. Initial results obtained with 16-slice MSCT scanners,which provide somewhat higher temporal and -through decreased slice thickness - improved spatial resolution, show promise that diagnostic accuracy may be increased while the number of coronary artery segments with nondiagnostic image quality may be reduced as compared to the prior generation of 4-slice scanners. Further studies are necessary to identify patient subgroups which might benefit from MSCT "noninvasive coronary angiography" in a clinical setting.