Comparison of myocardial blood flow quantification models for double ECG gating arterial spin labeling MRI: reproducibility assessment

Background: Arterial spin labeling (ASL) allows non-invasive quantification of myocardial blood flow (MBF). Double-ECG
\ngating (DG) ASL is more robust to heart rate variability than single-ECG gating (SG), but its reproducibility requires further
\ninvestigation. Moreover, the existence of multiple quantification models hinders its application. Frequency-offset-corrected-inversion (FOCI) pulses provide sharper edge profiles than hyperbolic-secant (HS), which could benefit
\nmyocardial ASL.
\nPurpose: To assess the performance of MBF quantification models for DG compared to SG ASL, to evaluate their reproducibility and to compare the effects of HS and FOCI pulses.
\nStudy Type: Prospective.
\nSubjects: Sixteen subjects (27 8 years).
\nField Strength/Sequence: 1.5 T/DG and SG flow-sensitive alternating inversion recovery ASL.
\nAssessment: Three models for DG MBF quantification were compared using Monte Carlo simulations and in vivo
\nexperiments. Two models used a fitting approach (one using only a single label and control image pair per fit, the
\nother using all available image pairs), while the third model used a T1 correction approach. Slice profile simulations were conducted for HS and FOCI pulses with varying B0 and B1. Temporal signal-to-noise ratio (tSNR) was
\ncomputed for different acquisition/quantification strategies and inversion pulses. The number of images that minimized MBF error was investigated in the model with highest tSNR. Intra and intersession reproducibility were
\nassessed in 10 subjects.
\nStatistical Tests: Within-subject coefficient of variation, analysis of variance. P-value <0.05 was considered
\nsignificant.
\nResults: MBF was not different across acquisition/quantification strategies (P = 0.27) nor pulses (P = 0.9). DG MBF quantification models exhibited significantly higher tSNR and superior reproducibility, particularly for the fitting model using multiple images (tSNR was 3.46 2.18 in vivo and 3.32 1.16 in simulations, respectively; wsCV = 16%). Reducing the
\nnumber of ASL pairs to 13/15 did not increase MBF error (minimum = 0.22 mL/g/min).
\nData Conclusion: Reproducibility of MBF was better for DG than SG acquisitions, especially when employing a fitting
\nmodel.
\nLevel of Evidence: 2
\nTechnical Efficacy: Stage 1