To investigate the changes of magnetic resonance diffusion tensor image after traumatic brain injury (DAI) in rats brainstem. At various stages, diffusion tensor image was used to measure apparent diffusion coefficient (ADC) and fractional anisotropy (FA), with immunostaining being used to determine Aquaporin 4 (AQP4).

Forty-eight rats were randomly divided into 6 groups. Five separate parallel groups of eight rats per group were injured and imaged at 3h, 6h，12h，24h，72h post-injury by a weight drop trauma model. Rats in DAI group were sacrificed for histology immediately after the scan. A control group of 8 rats was imaged and sacrificed for histology but not injured. Each group was studied by conventional MR imaging, diffusion tensor imaging and histologically examination including HE，silver staining, and immunohistochemistry of AQP4. The results of conventional MRI and...

Histologically examination showed axonal damage and brain edema in rats of DAI groups. AQP4 expression increased regulated in rat brainstem ((Fig.1), reached the peak values at 24h and decreased gradually afterwards(Fig.2). ADC value increased and reached the peak values at 12h, and also decreased afterwards(Fig.3). FA value decreased consecutively(Fig.4). There was significant correlation of ADC value and AQP4 expression in brainstem between DAI group and control subjects within 12h and between 24 to 72h (P <0.01) respectively. There was no significant correlation between 12h to...

The expression of AQP4 protein after DAI is time-dependent and possibly implicated in the formation and resolution of DAI-induced cerebral edema. ADC measurements in brainstem were correlated with AQP4 after DAI. Combining with AQP4 expression and ADC value were helpful for reflecting the classification between vasogenic brain edema and cytotoxic brain edema.

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W.B. Zheng MD Department of Radiology, Second Affiliated Hospital, Medical College of Shantou University, Shantou 515041, Guangdong, China This work is supported by Natural Science Foundation of Guangdong Province, China No.0700819, Science and Technology Planning Project of Guangdong Province, China No. 2005B33801010；No.2010B031600129