Hybrid Multi-Delay PCASL of Time-Encoded and Variable-TR Schemes for the Assessment of Cerebral Perfusion in Moyamoya Disease [Presidential Award Proceedings]

Multi-delay PCASL acquisition with a hybrid scheme that combines time-encoded and variable-TR schemes was developed. This hybrid scheme combines the advantages of a high signal-to-noise ratio (SNR) obtained using a time-encoded scheme with the timing flexibility of a variable-TR scheme. This study aimed to investigate the ability of a hybrid scheme for cerebral blood flow (CBF) and arterial transit time (ATT) quantification in patients with Moyamoya disease. A total of 13 patients with Moyamoya disease were included in the present study. The MRI protocol included a variable TR scheme with 12 delays (vTR12), a time-encoded scheme with seven delays (TEnc7), and a hybrid scheme with 4×3 delays (Hyb12). The temporal SNR (tSNR), CBF, and ATT were measured using a vascular atlas template. The tSNR of Hyb12 was significantly higher than those of vTR12 (P<0.0001) and TEnc7 (P<0.0001). The CBF of Hyb12 was significantly lower than that of vTR12 (P＝0.0186) and TEnc7 (P＝0.0005). The ATT of Hyb12 was significantly shorter than those of vTR12 (P<0.0001) and TEnc7 (P<0.0001). CBF measured with Hyb12 showed significant correlations and excellent agreement with those measured with vTR12 (r＝0.8269, ICC＝0.8966) and TEnc7 (r＝0.8586, ICC＝0.9585). The quantitative capability of CBF and ATT in the hybrid scheme was confirmed in the assessment of cerebral perfusion in Moyamoya disease.