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

Abstract

AbstractPurposeTo investigate and mitigate the influence of physiological and acquisition‐related parameters on myocardial blood flow (MBF) measurements obtained with myocardial Arterial Spin Labeling (myoASL).MethodsA Flow‐sensitive Alternating Inversion Recovery (FAIR) myoASL sequence with bSSFP and spoiled GRE (spGRE) readout is investigated for MBF quantification. Bloch‐equation simulations and phantom experiments were performed to evaluate how variations in acquisition flip angle (FA), acquisition matrix size (AMS), heart rate (HR) and blood relaxation time () affect quantification of myoASL‐MBF. In vivo myoASL‐images were acquired in nine healthy subjects. A corrected MBF quantification approach was proposed based on subject‐specific values and, for spGRE imaging, subtracting an additional saturation‐prepared baseline from the original baseline signal.ResultsSimulated and phantom experiments showed a strong dependence on AMS and FA (>0.73), which was eliminated in simulations and alleviated in phantom experiments using the proposed saturation‐baseline correction in spGRE. Only a very mild HR dependence (>0.59) was observed which was reduced when calculating MBF with individual . For corrected spGRE, in vivo mean global spGRE‐MBF ranged from 0.54 to 2.59 mL/g/min and was in agreement with previously reported values. Compared to uncorrected spGRE, the intra‐subject variability within a measurement (0.60 mL/g/min), between measurements (0.45 mL/g/min), as well as the inter‐subject variability (1.29 mL/g/min) were improved by up to 40% and were comparable with conventional bSSFP.ConclusionOur results show that physiological and acquisition‐related factors can lead to spurious changes in myoASL‐MBF if not accounted for. Using individual and a saturation‐baseline can reduce these variations in spGRE and improve reproducibility of FAIR‐myoASL against acquisition parameters.