Abstract 14190: Simultaneous Analysis of Myocardial Flow Reserve and Intra-Ventricular 4D Flow Using Hybrid ¹³ N-ammonia Positron Emission Tomography/Magnetic Resonance Imaging in Patients With Coronary Artery Disea

Introduction: Intra-left ventricular (LV) blood flow dynamics is closely related to wall kinetics and myocardial perfusion. 4D flow magnetic resonance imaging (MR) has been developed to simulate and quantify intra-LV blood flow. We aimed to evaluate the usefulness of simultaneous analysis of myocardial flow reserve (MFR) and intra-LV 4D flow measured by hybrid ¹³ N-ammonia positron emission tomography (PET)/MR in patients with coronary artery disease (CAD).

Methods: Forty patients (mean 65±18 years, male 32) with CAD who underwent pharmacological stress PET/MR were enrolled. MFR was calculated from a series of dynamic rest-stress PET scans. Simultaneously, 4D flow MR acquisition was performed during the stress PET scan. The intra-LV 4D flow was visually assessed, where the smooth flow was defined as normal pattern, and random, or reverse flow was defined as abnormal (Figure A). The velocity of LV inflow and outflow were measured.

Results: A normal flow pattern was found in 22 patients, while abnormal pattern was found in 18. MFR showed a significant correlation with the velocity of LV inflow and outflow (inflow: R = 0.552, P < 0.001; outflow: R = 0.563, P < 0.001). MFR was significantly lower in the abnormal flow compared to the normal flow (1.484 ± 0.559 vs. 1.931 ± 0.775, P = 0.041, Figure B). Additionally, when analyzing MFR in coronary artery territories, MFR in the left anterior descending artery was significantly lower in the abnormal flow compared to the normal flow (1.405 ± 0.526 vs. 1.881 ± 0.791, P = 0.029, Figure C).

Conclusion: Simultaneous analysis of MFR and intra-LV 4D flow has a potential to serve as a novel indicator for assessing the severity of ischemia in patients with CAD.