Current development of cardiac imaging with multidetector-row CT

Multidector-row CT (MDCT) with retrospective ECG gating allows scanning the entire heart with 1.25 mm slice thickness and 250 ms effective exposure ti me within 35 s investigation time. The resulting images allow for an accura te high-resolution assessment of morphological detail of both the coronary arteries and the cardiac chambers. Performing a contrast-enhanced MDCT angi ography (MD-CTA) in addition to a non-enhanced scan for the detection and q uantification of coronary calcifications may be indicated in patients with atypical chest pain and in young patients with high cardiovascular risk. Th is group of patients may show non-calcified plaques as the first sign of th eir coronary artery disease. As the proximal part of the coronary arteries is well displayed by MD-CTA it also helps to delineate the course in anomal ous coronary vessels. Additional information is drawn from the preoperative use of MD-CTA do determine the distance of the left internal mammarian art ery to the left anterior descending coronary artery prior to minimal invasi ve bypass grafting. Additional indications for MD-CTA are the non-invasive follow up after venous bypass grafting, PTCA, and coronary stent interventi ons. MD-CTA allows following the course of the coronary vessels to the leve l of third generation coronary segmental arteries. A definite diagonis to r ule out coronary artery disease can be reliably made in vessels with a diam eter of 1.5 mm or greater. With MDCT a number of different atherosclerotic changes can be observed in diseased coronary arteries. Non-stenotic lesions may show tiny calcifications surrounded by large areas of irregularly dist ributed soft tissue. Calcifications in this type of atherosclerotic coronar y artery wall changes appear as 'the tip of iceberg'. Heavy calcifications usually tend to be non-stenotic because of vessel remodelling resulting in a widening of the coronary vessel lumen. Therefore, heavy calcifications ap pear to ack like an 'internal stent' for a coronary vessel segment. Humps o f soft tissue either with or without calcifications are more likely to caus e significant coronary artery disease and con elate with stenoses of > 50% on selective coronary catheter. These humps consist of well-defined soft ti ssue in the coronary artery wall. The density of this soft tissue may Vary between 30-70 HU. In cases where a coronary vessel is occluded by thromboti c material, a typical sign is found with enlargement of the coronary vessel , a hypodense center and a hyperdense rim. Vessel occlusion without thrombu s may also appear within a collapsed and dense lumen. In addition to the in vestigation of the coronary arteries, CTA with MDCT is well suited to asses s the presence and morphology of myocardial scars and aneurysms, intracardi al tumors and thrombi. (C) 2000 Elsevier Science Ireland Ltd. All rights re served.