| Objective To evaluate the role of ultrasonic integrated backscatter (IBS) in assessing the pathological response to radiofrequency ablation (RFA) in normal rabbit liver,and to explore the radiofrequency lesions correlation between two-dimensional and pathological findings.Methods RFA lesions were created under ultrasonic guide in the normal liver of twenty-one healthy New Zealand white rabbits, which were divided into three groups randomly. HP Sonos 5500 image system with quantitative analysis function was used for IBS measurement. With the machine setting fixed, and optimal image obtained, twenty-one lesions were evaluated with ultrasonic IBS and two-dimensional before and after the treatment of radiofrequency ablation at 1day,7 days and 14 days. Further the measurements of IBS in the same depth were performed respectively. The IBS and its changes in the lesions and the regions of interest were examined and compared before and after the treatment. In the meantime, save the two-dimensional imaging and peripheral blood was taken out respectively before and after RFA. Animals underwent hepatic RFA were killed after performing ultrasonic IBS and imaging at 1day,7days and 14 days after the procedure respectively to study the pathology.Results 1.The standard IBS and the change of IBS% can well correlate the hispathological changes by RFA in the rabbit normal liver and can display the necrosis areas exactly. The values of ultrasonic IBS showed significant difference before and after the ablation. They was respectively : normal liver : 23.02±0.43dB, peripheral of the target :49.15±1.47dB, the change of IBS% was 0.5316,center of the target :54.15±1.31dB, the change of IBS% was 0.5748, the IBS of after RFA was higher than that before,the IBS of the center of target was higher than that of peripheral. The change of IBS %were over 50%, can be determined necrosis. The standard IBS(IBS%) and the change of IBS %can display the necrosis histopathological changes by RFA in normal rabbit liver. Through analyzing the values of standard IBS and IBS% and pathological findings, shows standard IBS and IBS% can well correlate the histopathological changes by RFA in the normal liver, with the increase of fibrin organization, the IBS increase constant,The change of IBS% over 50%.The IBS of different organize according the go up order was: normal liver, peripheral of the target, center of the target. The average image intensity (AII) and standard IBS(IBS%) of the normal rabbit liver was respectively 23.71±2.15dB,23.02±0.43dB.After RFA, the AII and IBS% became respectively 55.78±1.07dB, 54.15±1.31dB,were all higher than that before. The difference between two groups was significant (p<0.01). But the AII, IBS% of the normal liver around the lesions was no significant(p>0.05).That is say: there was no significant difference of IBS in the normal liver of the around between the before and after RFA. Significant differences of IBS were found between the normal liver and the center of target, and the normal liver and the peripheral of target. 2.The imaging of two-dimensional can be well show the necrotic areas, the necrotic areas of the two different ways measured was no significantly difference(p>0.05) .3. After RFA hepatic function changed apparently in seven days and restored gradually to the normal level in 14 days. Concrete variety : total protein(TP) and albumin(A) obviously lowers, total bilirubin(T-BIL),ALT,AST,AkP were all increased . Besides TP,ALP, the rest index sign were all restored on about 14 days. After RFA, the kidney function analyzes was BUN and Cr increased on the 1 shorterly,in a while recovered the normal level.Conclusion The IBS heralds a new method of noninvasive quantitative measurement in the assessment of therapeutic response to radiofrequency ablation of the rabbit's normal liver.
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