Effect of radiofrequency ablation on in vivo and in vitro renal tissue

    LIU Xi, DUAN Yunª²You, ZHAO Baiª²Shan, SUN Siª²Guo, BIAN Ling, BAO Guoª²Qiang, CHEN Sheng, RUAN Liª²Tao

    1Department of Ultrasound Diagnostics, 2Department of Orthopaedics, 3Department of General Surgery, Tangdu Hospital, Fourth Military Medical University, Xi¡¯an 710038, China

    ¡¾Abstract¡¿ AIM: To study the effect of radiofrequency ablation on the in vivo or in vitro renal tissues and to evaluate the veracity of ultrasonography measurement in renal radiofrequency. METHODS: Six rabbits were sacrificed for the in vivo experiment and ten in vitro kidneys were used in vitro experiment. The kidneys were exposed after anesthesia and then the electrode was inserted into the pole of the kidney. Radio frequency ablation was performed with different original power and ablation size. The time was recorded. Every kidney was scanned with ultrasonography and the parameters were recorded. The specimen was excided and measured anatomically and the difference was compared between ultrasonography and anatomy. RESULTS: ¢ÙThere were three layers between lesion and normal region: Carbonization region, coagulation necrosis region and edema cincture. ¢ÚOn the same electrode size and original power, in vivo condition seemed to need more time to reach the peak impedance. ¢ÛThe difference between ultrasonographical and anatomical size of lesions was significant in vivo but not significant in vitro. It seemed that the lesion in vivo was larger than that of in vitro under the same conditions (P<0.05). CONCLUSION: The size and shape of ablation lesion is related to the renal blood condition. Low original power is considered in plenty blood supplied tissues to get larger lesion area, but expanding space of radiofrequency coagulation in renal tissue demands caution. Ultrasonography is prone to overestimate or underestimate of lesion size at the instant moment of ablation. ......