Comparative Study of MRI and Photoacoustic Imaging on Brain Blood Perfusion Function of Rat/Mouse

The aim of this work is to assess the cerebrovascular reserve capacity (CVRC) by MR PWI and photoacoustic brain imaging with “ACZ” tolerance test in mouse and rat, and to compare their role in evaluating the CVRC. Experimental animals included 2 groups: Wistar-Kyoto rats (WKY) (12-week-old, 235~265g) were assessed by MRI and BALB/c mice (4-week-old, 25~35g body weight) were assessed by our photoacoustic imaging system. On photoacoustic imaging, the diameter of the vascular in the superficial layer of the mouse cortex were measured and compared between the resting and acetazolamide (Acz)-activated mice, which reflected cerebral blood flow (CBF) without blood sampling. MR PWI was performed respectively before and after acetazolamide administrated orally on a clinical 1.5 Tesla GE Signa MR fx/i whole-body MR system. The region of interest (ROI) was chosen in the bilateral frontal lobe to measure the value of rCBV, rCBF and MTT. The results show that there was statistical difference between the resting and acetazolamide (Acz)-activated animals in the values of the diameter of the vascular in the superficial layer of the mouse cortex by photoacoustic imaging and in the values of rCBV and rCBF（P＞0.05）of the rat by MRI. It was concluded that the method of PWI and photoacoustic imaging combined with the “ACZ stress test” can be used to evaluate the CVRC by measuring values of rCBV and rCBF and diameter of the vascular, respectively.