Single‐shot EPI for ASL‐CMR

Purpose To evaluate single‐shot echo planar imaging (SS‐EPI), as an alternative to snapshot balanced steady state free precession (bSSFP) imaging, for arterial‐spin‐labeled cardiac MR (ASL‐CMR). This study presents a practical implementation SS‐EPI tailored to the needs of ASL‐CMR at 3T and demonstrates sequential multi‐slice ASL with no increase in scan time. Methods Reduced field of view SS‐EPI was performed using a 2DRF pulse. A spin‐echo was used with crushers optimized to maximize blood suppression and minimize myocardial signal loss, based on experiments in 4 healthy volunteers. SS‐EPI was evaluated against the widely used bSSFP reference method in single‐slice ASL‐CMR in 4 healthy volunteers, during both systole and diastole. Sequential multi‐slice ASL‐CMR with SS‐EPI was demonstrated during diastole (3 slices: basal, mid, and apical short‐axis) and during systole (2 slices: mid and apical short‐axis), in 3 volunteers. Results Global myocardial perfusion for diastolic SS‐EPI (1.66 ± 0.73 mL/g/min) and systolic SS‐EPI (1.50 ± 0.36 mL/g/min) were found to be statistically equivalent (2 one‐sided test with a difference of 0.4 mL/g/min) to diastolic bSSFP (duration of 1 cardiac cycle, 1.60 ± 0.80 mL/g/min) with P ‐values of 0.022 and 0.031, respectively. Global myocardial perfusion for sequential multi‐slice experiments was 1.64 ± 0.47, 1.34 ± 0.29, and 1.88 ± 0.58 for basal, mid, and apical SAX slices during diastole and was 1.61 ± 0.35, and 1.66 ± 0.49 for mid and apical slice during systole. These values are comparable to published ASL‐CMR and positron emission tomography studies. Conclusion SS‐EPI is a promising alternative to bSSFP imaging for ASL‐CMR and can potentially improve the spatial coverage of ASL‐CMR by 3‐fold during diastole and 2‐fold during systole, without increasing scan time.