Invasive versus noninvasive (MSCT) coronary angiography. Importance of cardiac diagnostics with multislice computed tomography

Cardiac imaging with fast computed tomography (CT) is a quickly evolving field starting to become established in the cardiac routine work-up. The exclusion of coronary calcification is the most accurate noninvasive method to exclude significant coronary stenosis whereas the detection of calcification identifies coronary arteriosclerosis. The total calcium load correlates with the risk of coronary stenosis, but there is not a 1 : 1 relationship. CT angiography with contrast enhancement offers promises to increase diagnostic accuracy. 4-slice scanners acquire data with a slide width down to 1 mm. The spatial resolution of invasive coronary angiography cannot be achieved yet. Severe coronary stenosis may be excluded with 90% specificity if image quality is not impaired by artifacts, severe calcification, arrhythmia, and a heart rate > 70 beats/min. With present technology, about 26% of segments may not be adequately assessed. Despite these limitations CT angiography is a useful tool to reduce the number of invasive diagnostic angiography. In patients with known coronary artery disease (CAD), progression as well as stent occlusion can be assessed. Instent stenosis can only be diagnosed indirectly. The patency of arterial and venous grafts can be assessed very well including also the bypass insertion site. Actual studies on the significance of noncalcified plaques are in progress.A CT angiography should take place in order to avoid further exposure to radiation. Therefore, patients with typical angina or significant signs of coronary ischemia have to be investigated by invasive methods and do not profit from a CT scan. Preparation and implementation of this method should only be applied in cooperation with radiologists and cardiologists in an experienced center.