MRI of VX2 carcinoma in rabbits after radiofrequency ablation:Comparison with pathological findings / 中国医学影像技术

ABSTRACT

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.