Information about the coronary status is of greatest importance for the management of patients with Coronary Artery Disease (CAD).
Invasive coronary angiography is considered to be the gold standard for the evaluation of the coronary status. Cardiovascular CT is getting a more and more important role in selected patient groups, especially to rule out significant coronary stenosis in unclear chest pain. For the fist time in CT, the Definition Flash with its sub-mSv Heart scanning might allow for early detection of coronary heart disease to prevent potential myocardial infarction. Cardiovascular MR is not yet that suited for clinical all day routine, but offers advantages for specific indications like coronary anomalies. Echocardiography can provide additional physiological information through the analysis of the coronary flow reserve. The technical challenges in coronary imaging include a fast moving heart and coronary arteries, breathing and movement of the chest, and large density differences in the thorax, e.g. heart, spine, lung and diaphragm
Coronary angiography is capable to visualize even smallest coronary lumen alterations due to its high temporal and spatial resolution in all patients, irrespective of heart rhythm and heart rate. However it does not deliver any information about the coronary wall morphology. Coronary angiography is the only modality offering immediate therapeutic intervention in the case of a flow limiting coronary stenosis.
Coronary CT Angiography
Coronary CT angiography (CTA) is a useful diagnostic method in specific clinical situations, especially in acute patients with inconclusive results from initial ECG and lab testing (Appropriateness Criteria for Cardiac CT and Cardiac MRI). The diagnostic accuracy of coronary CTA relates to the detection of significant coronary artery stenosis (> 50%), diagnosed by invasive coronary angiography. Coronary CTA has a high negative predictive value (NPV) and therefore is especially useful for the exclusion of significant coronary artery stenosis. In several studies it could be demonstrated that cardiac CT not only improves quality of care for acute chest pain patients, but may also save money. Recent studies could demonstrate that Dual Source CT may overcome limitations of Single Source coronary CTA. Dual Source CT allows not only the evaluation of native coronary arteries, but also of stents and bypass grafts independent of the heart rate, e.g. in patients after heart transplantation.
Coronary MR Angiography
Coronary MR Angiography (MRA) is a promising technique for the diagnostic evaluation of the coronary arteries. According to the Appropriateness Criteria (Appropriateness Criteria for Cardiac CT and Cardiac MRI), CMR is indicated for the evaluation of coronary anomalies. The diagnostic accuracy to detect significant coronary stenoses is: sensitivity 72-93% and specificity 42-90%. Although MRA is not the method of choice for routine coronary evaluation, it can achieve better diagnostic performance compared to other non-invasive tests in patients with high coronary calcification. New non-invasive coronary MRA techniques, such as the 3D Whole-Heart MRA, enable a CT-like easy exam planning and image handling. 3D datasets can be reformatted in all planes and volume rendered images (VRT) can be created in a similar fashion. In a free-breathing acquisition, a 3D coronary MRA can be performed in less than 10 minutes. With motion adaptive respiratory gating, even diaphragm shifts can be compensated.
Publications of clinical experts
A) LCA without stenosis, SOMATOM Definition, Courtesy of Friedrich-Alexander University Erlangen-Nuremberg, Germany