Abstract 9764: Simultaneous Assessment of Coronary Flow Reserve and Left Ventricular Strain During Vasodilator Stress Measured by 13 N-ammonia Positron Emission Tomography/Magnetic Resonance Imaging

Abstract

Introduction: Hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI) is able to yield important information regarding molecular and functional imaging in a one-stop examination. The aim of this study was to investigate the relationship between coronary flow reserve (CFR) and left ventricular longitudinal strain (LVLS) using simultaneous acquisitions on hybrid 13 N-ammonia PET/MRI. Methods: Thirty-eight patients with suspected coronary artery disease (CAD) who underwent 13 N-ammonia PET/MRI were enrolled. Vasodilator stress was induced by intravenous injection of adenosine. CFR was calculated from dynamic acquisition of 13 N-ammonia PET. LVLS was evaluated by feature-tracked MRI. Myocardial flow reserve (MFR) and LVLS values were based on a 17-segment model and three coronary territories, left anterior descending artery (LAD), left circumflex artery (LCx), and right coronary artery (RCA). Results: We analyzed 577 myocardial segments in the left ventricle. LVLS under vasodilator stress was significantly increased compared with LVLS at rest in myocardial segments with MFR ≥2.0 (P<0.01), whereas there were no changes between LVLS under stress and LVLS at rest in the segments with MFR < 2.0 (P=0.24). Similarly, regional values of LVLS under vasodilator stress were significantly increased compared with those measured at rest in the coronary territories of LAD (P<0.01), LCx (P<0.01), and RCA (P<0.01) with MFR ≥ 2.0, whereas there were no differences between LVLS at rest and LVLS under stress in those territories with CFR < 2.0 (P=0.45). These data revealed that left ventricular strain under vasodilator stress was impaired in segments with lower CFR. Conclusion: Simultaneous assessment of regional CFR and LV strain was feasible using by 13 N-ammonia PET/MRI. 13 N-ammonia PET/MRI was able to detect not only impaired CFR but also morphological abnormalities, which may improve diagnostic and predictive capacity in patients with CAD.