CT-Based Myocardial Perfusion Imaging-Practical Considerations: Acquisition, Image Analysis, Interpretation, and Challenges

Abstract

Methods for non-invasive, cardiac risk assessment have historically relied on exercise stress testing with or without echocardiography or radionuclide imaging and pharmacological stress testing when appropriate. More recently, CT-based modalities like CT angiography (CTA) have been shown to reliably differentiate low from high-risk coronary disease. The advent of newer CT technology now allows for CT-based myocardial perfusion imaging (CTP) that provides functional information, that when analyzed with anatomic data from CTA, can provide a comprehensive risk assessment strategy. In this review, we discuss the research and implementation; as well as the quantitative, semiquantitative, and qualitative methods of image analysis of CT-based perfusion. We also discuss the present state of technology and challenges associated with the methodology. In each section, when appropriate, we provide some information regarding the translation of these methods being utilized in the international, multicenter CORE320 study that is evaluating the combined CT-based imaging (CTA and CTP) strategy of risk assessment in comparison to the combined reference standard of radionuclide myocardial perfusion imaging and invasive angiography.

A stepwise approach to the visual interpretation of CT-based myocardial perfusion

“…10 In subjects with no coronary disease, the mean (6 SD) TPR is 1.12 6 0.13, and it is considered potentially abnormal when it is ,0.99 or .1 SD below the mean normal TPR. 26 It has been shown that there is a significant inverse linear correlation between the TPR and the percentage of diameter stenosis as measured by coronary angiography (R 5 20.63, P 5 0.001). 10 For scoring of perfusion deficits as well as calculation of TPR, the myocardium may be divided into 13, 17, or 20 segments similar to that used for other tomographic imaging modalities.…”

Computed tomography

“…Using standard ECG-gated spiral CT protocols, the radiation exposure of 64-slice scanners exceeded that of single-photon emission tomography (SPECT, [15][16][17][18][19][20]. While the diagnostic performance of cardiac CT improved dramatically from 4-to 64-slice CT, this came at the expense of increasing exposure to radiation.…”

Cardiac CT for myocardial ischaemia detection and characterization—comparative analysis

“…This method has been used in an early animal study, 104 but no clinical trials are currently available for DMP CT . 105 As most available clinical trials have used a dual source CT system, a modified deconvolution method, compatible with the slower sampling rate of shuttle mode, has been most frequently used in available studies to date. 96,97,99,100,102 Since dynamic myocardial CT perfusion is a rather recent development, available clinical data are sparse and cut-off values have not been conclusively established.…”