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

Abstract

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.

Improved reproducibility for myocardial ASL: Impact of physiological and acquisition parameters

“…Our simulation and phantom results further show that a mismatch between true and quantification $$$ {\mathrm{T}}_{1,B} $$$ may render myoASL‐MBF mildly dependent on HR. Cardiac ASL has previously been reported in the literature with intra‐subject variability between 7.5% 27 and 28% 28 . In the present study, those values ranged between 26% and 39%.…”

Update on state‐of‐the‐art for arterial spin labeling (ASL) human perfusion imaging outside of the brain

“…The first employs the intensity difference between label and control images acquired at a single TI for quantification, assuming that the T1 of blood and myocardium are nearly equal. In this context, both single [66][67][68][69][70] and double [71][72][73][74] ECG gating techniques have been used. The former allows gating of the readout to a particular cardiac phase with the use of a fixed TI.…”

“…69 Systolic and diastolic perfusion measurements have been compared using compressed-sensing techniques in combination with a bSSFP readout. 74 EPI readout has been shown to facilitate the coverage of three myocardial slices (basal, midventricular, and apex), at the expense of lower tSNR than that obtained with bSSFP. 73 The validity of myocardial FAIR ASL to detect hyperemia in healthy subjects has been tested with mild forms of stress 66,77,83 and pharmacological vasodilation.…”

“…Scan time efficiency of free‐breathing FAIR ASL was improved using a TR of ∼4 s, which had similar mean signal and tSNR compared to longer TR sequences, allowing the acquisition of more images in the same scan time 69 . Systolic and diastolic perfusion measurements have been compared using compressed‐sensing techniques in combination with a bSSFP readout 74 . EPI readout has been shown to facilitate the coverage of three myocardial slices (basal, midventricular, and apex), at the expense of lower tSNR than that obtained with bSSFP 73 …”

Non-contrast myocardial perfusion in rest and exercise stress using systolic flow-sensitive alternating inversion recovery

“…However, with conventional image acceleration systolic FAIR suffers from increased physiological noise. Even though advanced image acceleration techniques such as compressed sensing allow reducing the acquisition time to approximate the shorter systolic rest period, so far, systolic FAIR has only been demonstrated during rest [ 27 ]. The objective of this study was to evaluate systolic FAIR during rest and exercise stress in 10 healthy subjects.…”