Development of fast multi-slice apparent T(1)mapping for improved arterial spin labeling MRI measurement of cerebral blood flow

Purpose To develop fast multi-slice apparent T-1(T-1app) mapping for accurate cerebral blood flow (CBF) quantification with arterial spin labeling (ASL) MRI. Methods Fast multi-sliceT(1app)was measured using a modified inversion recovery echo planar imaging (EPI) sequence with simultaneous application of ASL tagging radiofrequency (RF) and gradient pulses. The fast multi-sliceT(1app)measurement was compared with the single-sliceT(1app)imaging approach, repeated per slice. CBF was assessed in healthy adult Wistar rats (N = 5) and rats with acute stroke 24 hours after a transient middle cerebral artery occlusion (N = 5). Results The fast multi-sliceT(1app)measurement was in good agreement with that of a single-sliceT(1app)imaging approach (Lin's concordance correlation coefficient = 0.92). CBF calculated usingT(1app)reasonably accounted for the finite labeling RF duration, whereas the routine T-1-normalized ASL MRI underestimated the CBF, particularly at short labeling durations. In acute stroke rats, the labeling time and the CBF difference (Delta CBF) between the contralateral normal area and the ischemic lesion were significantly correlated when using T-1-normalized perfusion calculation (R= 0.844,P= .035). In comparison,T-1app-normalized Delta CBF had little labeling time dependence based on the linear regression equation of Delta CBF = -0.0247*tau + 1.579 mL/g/min (R= -0.352,P= .494). Conclusions Our study found fast multi-sliceT(1app)imaging improves the accuracy and reproducibility of CBF measurement.