Ultrasound-guided percutaneous laser and ethanol ablation of rabbit VX2 liver tumors

Background: Only a small percentage of patients with hepatocellular carcinoma (HCC) may benefit out of surgical resection. Thus, lots of these patients are in need of local control, such as percutaneous ethanol injection (PEI), percutaneous laser ablation (PLA), or radiofrequency thermal ablation (RF). Purpose: To investigate the effects of ultrasound-guided PLA combined with PEI on rabbit VX2 liver tumors, using conventional gray-scale ultrasonography (US), color/power Doppler (CD/PD)US, contrast-enhanced (CE) US, and histologic examination. Material and Methods: VX2 tumors were implanted in the livers of 80 rabbits. Fourteen days after implantation, animals were randomly separated into four groups of 20 rabbits. Treatment of the four groups was with: (i) PLA; (ii) PEI; (iii) combined therapy of PLA immediately followed by PEI; and (iv) combined therapy of PEI immediately followed by PLA. Conventional gray-scale US, CD US, PD US, and CE US were performed before and after ablation. The effects on ablated areas were assessed by histologic examination. Results: Conventional gray-scale US showed a clear boundary around the ablated area in groups 1, 3, and 4. An isoechoic treated region with an irregular boundary was seen in group 2. On CE US, coagulated areas demonstrated a perfusion defect. Both conventional gray-scale US and CE US showed that the ablated volume in group 4 was larger than that in groups 1, 2, and 3. CD US and PD US demonstrated residual tumor in the periphery of ablated areas in groups 1 and 2, but not in groups 3 and 4. CE US demonstrated no residual tumor in group 4, unlike in groups 1, 2, and 3. Examination of treated tumors demonstrated necrosis in the ablated zones and increasing surrounding fibrous bands in the four treatment groups. Residual viable tissue in group 4 was less than that in groups 1, 2, and 3. Conclusion: Combined therapy of PEI immediately followed by PLA can coagulate significantly larger volumes of tumor and reduce residual tumor.