Radiofrequency ablation in a pig liver model: effect of transcatheter arterial embolization on coagulation diameter and histologic characteristics.

To determine whether transcatheter arterial embolization (TAE) can alter radiofrequency (RF)-induced coagulation necrosis, we evaluated the morphology and histologic characteristics of RF ablation lesions combined with TAE in normal pig liver. Using a RF ablation system, consisting of a RF generator and 2-cm expandable LeVeen needle electrodes, nine lesions were generated by RF ablation combined with TAE and 11 lesions by RF ablation alone in five animals. On completion of treatment, the lesions were excised for gross and histologic examination. Gross examination demonstrated a core of ablated tissue surrounded by a narrow rim of hemorrhagic necrosis. The final shape of the lesion in the RF ablation group was frequently altered by patent intrahepatic vessels at the periphery of the lesion, whereas the lesions in the RF ablation and TAE group were spherical (P<0.05, chi(2)-test). The coagulation diameter was significantly larger in the RF ablation and TAE group than in the RF ablation group (28.7+/-4.2 vs. 24.1+/-3.2 mm, P<0.05). Histochemical (lactate-dehydrogenase, maleate-dehydrogenase and NADPH-diaphorase) stainings showed what appeared to be 100% cellular destruction in the ablated lesion and its hemorrhagic rim in both groups. We conclude that RF ablation combined with TAE induces greater and more spherical areas of coagulation necrosis in normal pig liver tissue than RF ablation alone.