Ultrasound-guided Percutaneous Laser Combined With Ethanol Ablation On Rabbit VX2Liver Tumors

Part1Establish of A VX2Rabbit Liver Tumor ModelObjective: To evaluate technical feasibility and experimental usefulness ofpercutaneous ultrasound-guided implantation of VX2carcinoma in rabbitliver.We compared percutaneous ultrasound-guided implantation and surgicalimplantation in establishing VX2rabbit liver tumor model investigated the valueof ultrasonography in the implantation process and the evaluation.Methods: Thirty New Zealand rabbits were randomly divided into two groups，each having15rabbits：group I: surgical implantation; group II: percutaneousultrasound-guided implantation. After implantation, On7d,14d and21d,respectively,5rabbits in each group were examined by using conventional2-dimensional gray-scale ultrasonography (US), color Doppler (CD) US, powerDoppler (PD) US, and contrast enhanced (CE) US. Pathological examination wasperformed by hematoxylin-eosin (HE).Results: A new percutaneous US-guided implantation was technically feasible in all rabbits. Evaluation parameters showed that the percutaneousultrasound-guided implantation method is less invasive than the surgicalimplantation. After implantation,13rabbits survived in group I, and13rabbitssurvived in group II. The tumor volume measured by conventional2-dimensionalgray-scale US increased from0.30±0.15cm3,9.23±2.65cm3on7d to on21d ingroup I, and from0.28±0.18cm3to8.90±2.52cm3in group II. No significantdifference existed between two groups (P>0.05). On CD US, PD US and CE US,before14d most tumors were hypervascular and some tumors were observed withvessels and the central hypovascular areas after14d.Conclusions: Percutaneous ultrasound-guided implantation of VX2carcinoma inrabbit liver is a less invasive alternative to the surgical implantation, achievingequally successful tumor growth in the liver. Conventional2-dimensionalgray-scale US, CD US, PD US and CE US were valuable in assessment of tumorgrowth.Part Two Experimental Studies of Effects ofUltrasound-guided Percutaneous Laser Ablation on RabbitVX2Liver TumorObjective: To evaluate the safety and effects of ultrasound-guided percutaneouslaser ablation (PLA) on rabbit VX2liver tumors by using a neodymium-yttrium-aluminum-garnet (Nd: YAG) laser fiber placed through a skinny needle.Material and Methods: Fourteen days after implantation of VX2tumors inlivers of60rabbits, animals were randomly separated into three groups, eachhaving20rabbits. Echo Laser tumor ablation equipment was used. It deliveredenergy: group Ⅰ (3W/1800J), group Ⅱ (5W/1800J) and group Ⅱ(7W/1800J). The volume of tumors and ablated regions in three groups are measured byconventional gray-scale US and CE US, the effects on ablated areas wereassessed in terms of CE US and histopathological examination.Results: Conventional gray-scale US showed ablated areas clear boundary, acentral core of anechoic vaporization, hyperechoic carbonization and surroundinghypoechoic in groupⅠ，Ⅱand Ⅱ, On CE US, coagulated areas depictedperfusion defect. Conventional gray-scale US and CE US showed: the ablatedvolume in group Ⅰ was smaller than that in group Ⅱ and Ⅱ. CD/PD US and CEUS showed residual lesions in periphery ablated areas in three groups. Thevolume of ablated regions in groupⅠand Ⅱ, Ⅰ andⅡ was compared withsignificant difference (P<0.05). The volume of ablated regions in groupⅡand Ⅱwas compared with no significant difference (P>0.05). Hematoxylin-eosinstaining demonstrated necrosis in ablated zones and increasing surrounding fibrabands in three groups.Conclusions: ultrasound-guided percutaneous laser ablation of liver tissue issafe in this rabbit tumors model. Percutaneous laser ablation can cause fast，precise and effective necrosis of the liver tumors.Part Three Ultrasound-guided Percutaneous LaserCombined with Ethanol Ablation on Rabbit VX2LiverTumorsBackground: Only a small percentage of patients with large hepatocellularcarcinoma (HCC) may benefit out of surgical resection. Thus, most of thesepatients are in need of a form of local control, such as percutaneous ethanolinjection (PEI), percutaneous laser ablation (PLA), or radiofrequency thermal ablation (RFA).Objective: To investigate the effects of ultrasound-guided PLA combined withPEI on rabbit VX2liver tumors by using conventional gray-scaleultrasonography (US), color/power Doppler (CD/PD)US, contrast-enhanced (CE)US, histopathology examination and liver function.Material and Methods: Fourteen days after implantation of VX2tumors inlivers of80rabbits, animals were randomly separated into four groups, eachhaving20rabbits:(Ⅰ) PLA;(Ⅱ) PEI;(Ⅱ) combined therapy of PLAimmediately followed by PEI;(Ⅳ) combined therapy of PEI immediatelyfollowed by PLA. The length, width, depth and volume of tumors and ablatedregions in four groups are measured by conventional gray-scale US and CE US,the effects on ablated areas were assessed in terms of histopathologicalexamination and liver function.Results: Conventional gray-scale US showed ablated areas clear boundary, acentral core of anechoic vaporization, hyperechoic carbonization and surroundinghypoechoic in group Ⅰ, Ⅱ and Ⅳ, and the irregular ablation region withisoechoic in group Ⅱ. On CE US, coagulated areas depicted perfusion defect.Conventional gray-scale US and CE US demonstrated: the ablated volume ingroup Ⅳ was larger than that in group Ⅰ, Ⅱ and Ⅱ. In ablate areas, CD/PD USshowed residual lesions in groupⅠ and Ⅱ, but no residual lesion in group Ⅱ andⅣ. CE US represented no residual lesion in periphery ablated areas in group Ⅳthan that in groupⅠ, Ⅱ and Ⅱ. The length, width, depth and volume of tumorsand ablated regions in group Ⅱ and Ⅳ was compared with significant difference(P<0.05). Hematoxylin-eosin staining demonstrated necrosis in ablated zones andincreasing surrounding fibra bands in four groups, residual viable tissues inablated zones of group Ⅳ were less than those of group Ⅰ, Ⅱ and Ⅱ. In four groups after ablation ALT increased on the first day, and decreased to level ofbefore ablation in fourteen days.Conclusion: Combined therapies of PEI immediately followed by PLA cansignificantly coagulate larger volumes of tumor and reduce residual lesions.