Impact Of The Percutaneous Ultrasound-guided Lauromacrogol Ablation In VX2 Rabbit Liver Tumor Models

Objectives To assess whether US-guided percutaneous lauromacrogol ablation(PLA)could be a new ablation therapy to replace percutaneous ethanol ablation(PEA)in the treatment of small HCC.Methods A total of 27 healthy New Zealand white rabbits were implanted with tumor blocks under ultrasound guidance to establish rabbit VX2 small hepatocellular carcinoma model.Two weeks later,VX2 tumor-bearing rabbits were randomly divided into three groups:percutaneous lauromacrogol ablation group(PLA),percutaneous ethanol ablation group(PEA),and blank control group(BC).After ultrasound(US)and contrast-enhanced ultrasound(CEUS)examination,the drugs were injected into the tumor under US guidance.Blood samples were taken from 3 rabbits selected randomly in each group to detect the concentrations of alanine aminotransferase(ALT),aspartate aminotransferase(AST),blood urea nitrogen(BUN)and creatinine(Cr)before treatment,and the 1st,3rd,7th day after treatment.The rest of the rabbits were examined by US and CEUS on the 3rd,5th and 7th day after treatment,and the time intensity(TIC)curve was analyzed.All the remaining rabbits were sacrificed on the 7th day after the treatment,and the specimens were stained with hematoxylin-eosin staining(H&E)and immunohistochemistry staining(VEGF,Ki67).Results(1)A total of 21 rabbits were successfully modeled,3 rabbits were died of bleeding and infection,and 3 rabbits had no tumor formation in the liver;(2)Liver and kidney function:No significant changes of BUN and Cr levels in each group before and after treatment;ALT and AST levels in PEA group were significantly increased after treatment(P<0.05),and returned to the level before treatment on the 7th day after treatment,however,the PLA group and control group had no significant differences.There were no significant changes of ALT and AST in the BC group before and after treatment(P>0.05).(3)2-D US:Fourteen days after tumor inoculation,all the tumors presented sphere or sphere-like homogeneous hypo-or even isoechoic masses with clear contour on 2-D US images.Five days after treatment,the tumors in the PEA were heterogeneous echoic and deformed with ill-defined margin but no obvious changes in the PLA and BC group.(4)CEUS and TIC:CEUS imaging showed that the tumors were significantly enhanced with abundant and inhomogeneous blood perfusion in the early arterial phase and then quick wash-out of contrast agents in all groups before the treatment.After the treatment,CEUS results showed that the unique tumor enhancement vanished,instead of a significant perfusion defect in the tumor with few rim enhancement still visible at the edges in both the PLA group and the PEA group whereas the BC group still showed "rapid wash-in and wash-out" vascular pattern without perfusion defect.The ratio of tumor to liver parenchyma ’A×k’ post-treatment was less than 1 and the ratio pre-treatment was greater than 1 in both the PLA group and the PEA group(p<0.05).However,there were no significant differences in the ratio of the BC group all the time(p>0.05).(5)Tumor volume:Before ablation,there were no significant differences in tumor volumes of those three groups.On the 3rd day after the treatment,tumor volumes in the PEA and PLA group were significantly reduced compared with those in the BC group(p<0.05)while there were no significant differences between the PEA and PLA group.On the 7th day after the treatment,both PEA and PLA demonstrated significantly smaller than the BC group(p<0.05),and the PLA group was smaller than the PEA group(p<0.05).Meanwhile,the mean tumor growth inhibition rate of the PLA group was 76%,which was higher than that in the PEA group(51%).(6)H&E:Three different types of necrosis in the tumor on day 7 post-treatment.There was a large patchy infarction in the tumor with a marginal residual active tumor surrounded by a rim of new inflammatory bands in PEA.However,there was a large patchy necrosis in the tumor and the inflammatory bands which were mainly induced by the VX2 implantation in the PLA group.And fewer inflammatory tissue without any active tumor cells remained compared to the PEA was observed under microscope.Besides,the adjacent hepatocytes were all ballooning degeneration in both PLA and PEA.Comparatively,spontaneous discrete necrosis with irregular and map appearance in the tumor was shown in the BC group.(7)Immunohistochemistry staining:The ki-67 staining was negative in the necrosis tumor in the PLA group.However,the remaining active tumor cells showed positive ki-67 staining in the PEA group which was less than that in the BC group.Similarly,negative VEGF staining of the necrosis tumor was in the PLA group,but the PEA group showed more positive VEGF staining in the remaining active tumor cells than that in the BC group.Conclusions The ultrasound guided percutaneous lauromacrogol ablation therapy is a promising approach for small HCC.