Influence of the Imaging Method on Regional Cerebral Blood Flow Value in Arterial Spin Labeling (ASL): Comparison of Pulsed-ASL with Two-dimensional Acquisition and Pseudo-continuous-ASL with 3D Spiral Acquisition

Purpose: The purposes of this study were to compare regional cerebral blood flow (rCBF) images acquired by the pulsed arterial spin labeling with two-dimensional acquisition (PASL-2D) and the pseudo-continuous-ASL with three-dimensional spiral acquisition (pCASL-3D spiral), and to clarify the characteristics of rCBF values in both ASL methods. Methods: PASL-2D and pCASL-3D spiral were performed in five healthy volunteers with no history of brain disease using 3T scanners from two venders in the same center. 3D T1-weighted images and rCBF images were acquired by both ASL methods for a total of 3 sessions: twice at the initial visit (1st and 2nd), and 1 hour and 1 week later. The rCBF images calculated by each MR machine were anatomically standardized using SPM12. The regions of interest (ROIs) were set on the territory of the anterior cerebral artery (ACA), the middle cerebral artery (MCA), and the posterior cerebral artery (PCA). Mean and relative rCBF values were calculated at each arterial territory in each session. Reproducibility for rCBF value in each method was analyzed using Bland-Altman plots, the coefficient of repeatability (CR), and the repeatability index (RI). Results: In all sessions, mean values of rCBF were the highest at PCA for PASL-2D and at MCA for pCASL-3D spiral. RIs of pCASL-3D spiral were lower than those of PASL-2D in all arterial territories. Conclusion: In the PASL-2D and the pCASL-3D spiral, we confirmed the characteristics of the mean and reproducibility of rCBF values in each arterial territory.