Abstract 20468: Regional Myocardial Blood Flow Variability Is Associated With the Presence of Coronary Artery Disease in Clinical Rubidium-82 Cardiac Positron Emission Tomography

IntroductionMyocardial Perfusion Imaging (MPI) with Rb-82 PET is increasingly used clinically and has improved sensitivity and specificity for detecting the presence of coronary artery disease (CAD). In addition to MPI, Rb-82 PET provides global and regional quantitative myocardial blood flow (MBF) measurements. The interpretation of regional MBF and myocardial blood flow reserve (MBFR) is still unclear, however, as both epicardial CAD and microvascular function contribute to MBF and MBFR for a given territory.HypothesisCoronary microvascular disease (CMVD) is a global myocardial process reflected in global MBFR, whereas CAD is predominantly regional. We therefore hypothesize that regional MBF can be used to differentiate between CAD and CMVD and that increased regional variability in MBF indicates the presence of CAD.MethodsThis is a single center retrospective study of consecutive patients who underwent dipyridamole Rb-82 PET studies between February 2012 and August 2014. Studies were performed on a Siemens Biograph mCT PET/CT system and syngoMBF software was used for regional and global MBF and MBFR calculations. Regression analysis, discretization analysis, and student’s t-test were used to evaluate the relationship between regional MBF and the presence of obstructive CAD by angiography.ResultsThis study included 1282 patients, 395 (30.9%) of whom had coronary angiography. There was no relationship between regional MBFR obtained with clinical Rb-82 PET and coronary artery stenosis by coronary angiography. However, we developed a novel variable which is associated with the presence of CADSDstress / MBFRglobal, where SDstress is the standard deviation in regional stress MBF measurements and MBFRglobal represents the global MBFR for a given patient. This variable correlated with the presences of CAD (p = 0.0041), and a ratio of greater than 0.21 was highly suggestive of CAD.ConclusionsWe define a new variable based on variability in regional stress MBF that is associated with the presence of CAD in clinical cardiac Rb-82 PET studies.