Hepatic cryosurgery via minilaparotomy in a porcine model - An alternative to open cryosurgery

Background: Cryosurgery of liver lesions is becoming increasingly accepted for the ablation of liver tumors. Attempts at laparoscopic cryosurgery have been very limited and often need to be converted to open laparotomy due to the complexity of the procedure. Methods: Seven domestic pigs were anesthetized, and 17 small (0.7 cm mean diameter) tumor mimicking agar "lesions" were percutaneously placed in the liver. Two small subcostal incisions (similar to 2.0 cm) were placed, and an endocavitary ultrasound transducer (with a 2.4-mm cryoprobe mounted on it) was placed on the liver surface. Lesions were localized and directly punctured with one or two cryoprobes under ultrasound guidance, and a single 15-min freeze was undertaken. The animals were then killed, and their livers were removed and serially sectioned. Results: Total time for probe placement was approximately 10 min after incisions had been made. Animals tolerated the procedure well and all survived until they were killed. No intraabdominal complications were detected at exploration. Mean cryolesion dimensions were 3.0 cm (single probe) and 3.3 cm (dual probe) (p > 0.05). Positive margins were detected in one lesion treated with a single probe, and in none of the lesions treated with dual probes. Mean margins were 0.9 cm: 1.2 cm for the single probe and dual probe techniques, respectively. Liver surrounding control agar lesions demonstrated a thin rim of necrosis, approximately 0.5 mm wide. Conclusions: We conclude that minilaparotomy is an effective, safe, and simple method for performing hepatic cryosurgery in this animal model. This minimally invasive technique may benefit a subset of patients with lesions in accessible locations. Lesions in posterior locations may not be as amenable to this technique due to deterioration of ultrasound image quality in the far field.