Dynamic Computed Tomography Myocardial Perfusion Imaging for Detection of Coronary Artery Disease

Coronary artery computed tomographic angiography (CTA) is a widely used, highly accurate technique for the detection of coronary artery disease (CAD), with sensitivity and negative predictive values of over 90% (1-4). Patients with normal CTA findings have an excellent prognosis and do not require further testing for CAD (5). However, like invasive coronary angiography (QCA), CTA is an anatomic test and, unless lesions are very severe (\>90% stenosis), cannot reliably predict the impairment of flow (functional significance) of intermediate grade stenoses. For this reason, in approximately 15-25% of patients, additional functional testing may be required after CTA, usually in the form of stress testing (6-8). Stress testing is commonly done by exercise or pharmacologic stress with electrocardiographic monitoring and often, imaging of myocardial perfusion by nuclear scintigraphy (MPI) or detection of abnormal contraction by echocardiography. This requires a separate procedure, entailing time, expense and limited risk. Furthermore, in patients with previously known CAD, CTA alone is not an adequate test, because in most cases there are multiple lesions that are possible sources of ischemia. Over the last 10 years, these investigators and others around the world have developed a method of imaging myocardial perfusion by CT (CTP). This test is an adjunct to the usual Cardiac Computed Tomography Angiography (CCTA) procedure and can be done immediately thereafter, using conventional pharmacologic stress agents. It has demonstrated accuracy in many single center trials, and in this large multicenter study, the CORE320 trial (9,10) which showed a high accuracy in predicting the combined results of QCA plus MPI testing and a second multicenter trial established non-inferiority of myocardial CTP compared with nuclear stress testing (11,12). Additionally, this investigator group has published a direct comparison of diagnostic performance of myocardial CTP imaging and SPECT my