A Narrative-Review on Transient Ischemic Dilatation from Single Photon Emission Computed Tomography Myocardial Perfusion Imaging

Context: Transient ischemic dilatation (TID) of the left ventricle is a non-invasive marker of suspected or known Coronary Artery Disease (CAD), and is used for the prediction of prognosis. Because the value of TID has been emphasized by current publications in clinical nuclear cardiology field, the current review of the literature was conducted to present comprehensive overview on the findings in this field.
Evidence Acquisition: Relevant literature was obtained by searching online databases, including MEDLINE/PubMed, Google Scholar, and Science Direct using the following keywords: transient ischemic dilation, Single Photon Emission Computed Tomography Myocardial Perfusion Imaging (SPECT MPI), procedural guidelines for myocardial perfusion imaging, and coronary artery disease. Articles were inspected to obtain good agreement criteria pertinent to the objective of the study. Overall, 21 relevant articles were selected to be included in the review.
Stress-induced subendocardial hypoperfusion, post-ischemic stunning, and impaired coronary flow reserve have been reported as common causes of TID. Transient Ischemic Dilatation can be easily measured by available automatic software on the market, including Emory Cardiac Toolbox, 4D-MSPECT, etc. A close correlation between TID and LV volume/function has been emphasized by previous researchers. Transient Ischemic Dilatation, in the setting of a cardiac SPECT MPI with abnormal findings, has been known to be a robust indicator of severe/extensive CAD and future cardiac events. However, only a limited number of publications are available for its probable use in the setting of normal MPI, especially based on patients at high-risk and those with TID.
By using an upper limit value of TID that is derived according to the optimum imaging procedure of a particular laboratory, routine reporting of TID measurement as part of conventional SPECT MPI analysis may be useful.