Objective To explore the value of MR diffusion tensor imaging ( DTI) in diagnosis of traumatic Axonal injury ( TAI) .Methods Twenty nine patients with traumatic brain injury ( TBI) and matched 22 control subjects were performed with DTI . Fractional anisotropy ( FA) was calculated from semioval center , corpus callosum , internal capsule and pons of controls and TBI pa-tients.According to Glasgow Score (GCS), TBI patients were divided into mild group (GCS≥13) and moderate-severe group (GCS≤12), each group compared with control group in FA value .The correlation between FA values in different regions and GCS score were analyzed in DTI group .Results FA value of semioval center was decreased in mild DTI group ( P <0.01 ) .FA values of semio-val center , corpus callosum , and internal capsule were decreased in moderate-severe DTI group ( P <0.05 ) .The FA values in semio-val center , corpus callosum , and internal capsule were positively correlated with GCS score in TBI group ( P <0.05 ) .Conclusions DTI is sensitive to detect the traumatic axonal injury??Changes of FA value in ROIs can access the severity of axonal injury ?? which ishelpful for diagnosis earlier and improving prognosis.

Objective To evaluate the effect of MRI in reflecting the pathological changes of VX2 carcinoma in rabbits after radiofrequency ablation (RFA) . Methods RFA was performed in the livers of 24 rabbits with planted VX2 carcinoma. The rabbits were divided into 4 groups. After RFA, the rabbits were killed after MR imaging on 0, 1, 2, and 4 weeks, respectively. The correlation between MRI and pathological findings was analyzed. Results In the acute phase, coagulative necrosis of the ablated tumors and inflammatory reaction with hyperemia around were detected at microscopic examination. The ablated tumor showed as hypointensity on T1WI and hyperintensity on T2WI, while rim of high signal intensity on T1WI and low signal intensity on T2WI was found. Gadolinium-enhanced MRI showed a thin high signal rim surrounding the central coagulative necrosis. In the subacute phase, extensive coagulative necrosis and marked infiltration by neutrophils, lymphocytes, macrophages and a peripheral fibrous generation rim were observed microscopically on the ablated tumor. The ablated tumor showed iso-or hyperintensity on T1WI and hypointensity on T2WI, while the periphery of ablated lesions was hypointensity on T1WI and hyperintensity on T2WI. There was prominent rim enhancement along the ablated margin. In the chronic phase, peripheral fibrous rim became obvious, more regular and thicker than at subacute phase as hypointensity on T1WI and T2WI, and unenhancement was observed. Residual or recurrence of tumor was found in 17 rabbits as hypointensity on T1WI and hyperintensity on T2WI, and irregular, thicker rim or nodular enhancing abnormalities. Conclusion MRI can effectively show the histopathological tissue changes of rabbit VX2 carcinoma after ablation and demonstrate the residual or recurrence of tumor.