Myocardial arterial spin labeling in systole and diastole using flow‐sensitive alternating inversion recovery with parallel imaging and compressed sensing

Quantitative myocardial perfusion can be achieved without contrast agents using flow‐sensitive alternating inversion recovery (FAIR) arterial spin labeling. However, FAIR has an intrinsically low sensitivity, which may be improved by mitigating the effects of physiological noise or by increasing the area of artifact‐free myocardium. The aim of this study was to investigate if systolic FAIR may increase the amount of analyzable myocardium compared with diastolic FAIR and its effect on physiological noise. Furthermore, we compare parallel imaging acceleration with a factor of 2 with compressed sensing acceleration with a factor of 3 for systolic FAIR. Twelve healthy subjects were scanned during rest on a 3 T scanner using diastolic FAIR with parallel imaging factor 2 (FAIR‐PI2(D)), systolic FAIR with the same acceleration (FAIR‐PI2(S)) and systolic FAIR with compressed sensing factor 3 (FAIR‐CS3(S)). The number of analyzable pixels in the myocardium, temporal signal‐to‐noise ratio (TSNR) and mean myocardial blood flow (MBF) were calculated for all methods. The number of analyzable pixels using FAIR‐CS3(S) (663 ± 55) and FAIR‐PI2(S) (671 ± 58) was significantly higher than for FAIR‐PI2(D) (507 ± 82; P = .001 for both), while there was no significant difference between FAIR‐PI2(S) and FAIR‐CS3(S). The mean TSNR of the midventricular slice for FAIR‐PI2(D) was 11.4 ± 3.9, similar to that of FAIR‐CS3(S,) which was 11.0 ± 3.3, both considerably higher than for FAIR‐PI2(S,) which was 8.4 ± 3.1 (P < .05 for both). Mean MBF was similar for all three methods. The use of compressed sensing accelerated systolic FAIR benefits from an increased number of analyzable myocardial pixels compared with diastolic FAIR without suffering from a TSNR penalty, unlike systolic FAIR with parallel imaging acceleration.