Abstract
Breath-hold ECG-gated cardiovascular magnetic resonance (CMR) imaging is challenging during exercise due to motion, ECG-problems, and lengthy scans. To facilitate time-resolved volumetric measures from exercise-CMR, we aimed to develop a method for constructing time-resolved ventricular cines from real-time free-breathing exercise-CMR. Time-resolved ventricular cines were semi-automatically constructed from real-time exercise-CMR by identifying end-expiratory timeframes, identifying one R-R interval within these timeframes, and synchronizing R-R intervals across slice positions. To investigate utility, ECG-gated rest CMR and real-time exercise-CMR images were collected from ten healthy volunteers and ten heart failure patients. The consistency of the left ventricular mass (LVM) was assessed between rest and exercise at end diastole (ED), mid systole (MS), end systole (ES), and early rapid filling (ERF). When comparing LVM between rest and exercise for healthy volunteers, bias ± SD was 1.5 ± 2.7 g at ED, 0.9 ± 3.3 g at MS, 1.3 ± 3.3 g at ES, and 1.2 ± 3.3 g at ERF. When comparing LVM between rest and exercise for heart failure patients, bias ± SD was 1.6 ± 2.8 g at ED, 1.0 ± 2.7 g at MS, 1.5 ± 2.6 g at ES, and 1.6 ± 2.5 g at ERF. The bias ± SD between ED and ES in standard rest images was 0.0 ± 0.7 g for healthy volunteers, and 0.0 ± 0.5 g for heart failure patients. The method for constructing time-resolved ventricular cines from real-time exercise-CMR demonstrated utility for time-resolved volumetric measurements in healthy volunteers and heart failure patients.