Objective To explore the feasibility of tracking migration and distribution of SD-rat adipose derived stem cells (ADSCs) labeled with Polyethylene Glycol/Polyehthyleneimine modified superparamagnetic iron oxide (PEG/PEI-SPIO) in rats with chronic cerebral ischemia using MRI.Methods Thirty female SD rats underwent permanent occlusion of bilateral common carotid arteries 6 months were divided into PEG/PEI-SPIO labeled group and unlabeled group (each n =15).Labeled or unlabeled ADSCs suspension was injected into the right ventricle of rats in two groups,respectively.MR scans were performed at the 7th,14th and 21st day after transplantation for each 5 rats.T2 value of T2mapping sequence in hippocampus,cortex and cerebellum were measured.Then the rats were scarified,and the brains were obtained,and Prussia dyeing was performed.Under high magnification,blue dye cells at each time points and brain area were counted.T2 values and blue dye cells were statistically analyzed.Results Class round hypointensity areas were detected in temporol-parietal cortex and hippocampus in both groups on T2WI,T2* WI and SWI.T2 value of the right temporolparietal cortex and hippocampus in the labeled group was shorter than those of the unlabeled group on the 14th day after transplantation (P=0.013,0.045).T2 value of the right temporol-parietal cortex in the labeled group was shorter than that of the unlabeled group on the 21st day after transplantation (P=0.007).The number of blue dye cell of the right temporol-parietal cortex on the 14th and 21th day,hippocampus on the 14th day in the labeled group were more than those of the unlabeled group after transplantation (P=0.029,0.032,0.043).Conclusion ADSCs labeled with PEG/PEI-SPIO transplanted into lateral ventricle of SD rat could migrate to the damaged areas caused by chronic cerebral ischemia.It is possible to use quantitative MRI to track migration and distribution of ADSCs labeled with PEG/PEI-SPIO in rat brain.