Serial MR Analysis of Permanent and Transient Cerebral Ischemia in a Rat Model: High and Low B Value Diffusion Weighted Imaging and Diffusion Tensor Imaging

Ji-hoon Kim¹, Kee-Hyun Chang, Chul Ho Sohn, Sung Hong Choi, Yoo Jung Yim, Chang Min Park, In Chan Song

We tried to determine the serial changes in FA, ADC and DWI signal intensity at high and low b values during early cerebral ischemia and transient ischemia and investigated their relationships. With 30 male Sprague-Dawley rats of middle cerebral artery occlusion (MCAO) of the suture occlusion model, PWI, DTI, high and low b value DWI were performed for hyperacute (n=9) and acute (n=13) permanent ischemia groups and transient (n=8) ischemia group. Although time-ADC curve showed early initial decrease until 3 hour and then increasing tendency, Time FA curve showed initial increase, transient plateau until 1 hour, and then sequential decrease in permanent ischemia group. In transient ischemia group, FA showed transient reversibility and secondary decay in transient ischemia group, correlating with ADC change. Although the lesion contrast ratio of DWI in early ischemic tissue was larger at high b value. But, the lesion contrast ratio of ADC map was smaller at high b value than low b value. These results might be related to the initial shift of water from extracellular to intracellular space and biexponential decay of cerebral water diffusion.