Brundage B H
Department of Medicine, University of California at Los Angeles, School of Medicine, USA.
Am J Cardiol. 1995 Apr 13;75(11):69D-73D.
Ultrafast computed tomography (CT) has been available for the clinician for nearly 10 years. Although cost, as well as availability of competing technologies, have limited its application, several investigative groups have demonstrated the feasibility of measuring regional myocardial blood flow by this method. Ultrafast CT provides accurate measurements when myocardial blood flow is normal or reduced. However, when flow is increased (e.g., by pharmacologic vasodilation), the technique underestimates flow. (This can apparently be corrected by using a complex curve-fitting technique.) Direct injection of contrast medium into the aorta distinguishes differences in endocardial and epicardial blood flow. Although imaging of myocardial perfusion has proven clinical value, there is a need for new noninvasive approaches for detecting silent coronary atherosclerosis before coronary events occur. Here it is possible to make use of the close association between coronary atherosclerosis and coronary intimal calcium, recognized over 35 years ago. Even though the amount of coronary calcium is a function of age, individuals with coronary artery disease usually have greater amounts, and the greater the number of coronary vessels with calcium, the greater the likelihood of obstructive coronary disease. Ultrafast CT has proven value for visualizing coronary calcium. No contrast medium is required and radiation exposure is approximately 425 mrads.
超快速计算机断层扫描（CT）已可供临床医生使用近10年。尽管成本以及其他竞争技术的可用性限制了其应用，但几个研究小组已证明通过这种方法测量局部心肌血流量的可行性。当心肌血流量正常或减少时，超快速CT可提供准确的测量结果。然而，当血流量增加时（例如，通过药物性血管舒张），该技术会低估血流量。（显然，这可以通过使用复杂的曲线拟合技术来校正。）将造影剂直接注入主动脉可区分心内膜和心外膜血流量的差异。尽管心肌灌注成像已证明具有临床价值，但仍需要新的非侵入性方法来在冠状动脉事件发生前检测无症状冠状动脉粥样硬化。在此，可以利用35多年前就已认识到的冠状动脉粥样硬化与冠状动脉内膜钙之间的密切关联。尽管冠状动脉钙的含量是年龄的函数，但患有冠状动脉疾病的个体通常含量更高，并且有钙的冠状动脉血管数量越多，发生阻塞性冠状动脉疾病的可能性就越大。超快速CT已证明在显示冠状动脉钙方面具有价值。无需使用造影剂，辐射暴露量约为425毫拉德。
