Multi-delay arterial spin labeling using a variable repetition time scheme in Moyamoya disease: Comparison with single-delay arterial spin labeling

Purpose: To present a multi-delay arterial spin labeling (ASL) protocol that obtains the cerebral blood flow (CBF) considering the arterial transit time (ATT), and to assess the correlations with an iodine-123-N-isopropyl-p-iodoamphetamine single-photon emission computed tomography (¹²³I-IMP SPECT) reference standard between multi-delay ASL and single-delay ASL in patients with Moyamoya disease. Method: We retrospectively analyzed the images of 23 patients with Moyamoya disease (4–73 years, 5 men, 18 women), each of whom was imaged with 10-delay ASL using the variable repetition time (TR) scheme, single-delay ASL, and SPECT. Pearson correlation coefficients were calculated between the CBF values of each ASL and SPECT in the three divisions of the ATT, which we categorized as fast, normal, and slow regions. The threshold for statistical significance was set at P < 0.05. Results: The CBF measured by multi-delay ASL and single-delay ASL were positively correlated with that measured by SPECT, with correlation coefficients of 0.6701 and 0.5637, respectively (P < 0.001). In the fast, normal, and slow ATT divisions, the correlation coefficients between the CBF measured by multi-delay ASL and that measured by SPECT were 0.6745, 0.7055, and 0.6746, respectively. Similarly, the correlations between the CBF measured by single-delay ASL and that measured by SPECT were 0.3811, 0.5090 and 0.6178, respectively. Conclusions: Multi-delay ASL using the variable TR scheme showed a higher correlation with ¹²³I-IMP SPECT than single-delay ASL for measuring the CBF. The variable TR scheme potentially improved the quantification of CBF on ASL imaging.