To evaluate novel, 17-gauge cryoprobes with a modified heat exchange mechanism to evaluate the area of ablation that could be achieved with 17-gauge (1.47-mm) cryoprobes.

Eleven pigs were divided into four groups. Each animal underwent laparoscopic creation of three cryolesions with an ellipical iceball-generating 17-gauge cryoprobe (group 1), one that generates a teardrop-shaped iceball (group 2), a template of three standard 17-gauge cryoprobes (group 3), or a single, standard, large-caliber (3.4-mm) cryoprobe (group 4). Each cryolesion was created with a standard double-freeze cycle. Intraoperative ultrasonography was used to measure the maximal iceball dimensions, and the renal temperatures were measured with a thermocouple. The animals were killed after 14 days. The gross lesion size and histopathologic area of necrosis were documented.

The mean temperature for the surrounding renal parenchyma was not significantly different among the groups. No statistically significant difference was noted in the size of the gross or histopathologic lesions created among the four groups. The gross lesion size correlated statistically significantly with the histologic area of necrosis (P <0.01).

Despite the diminutive size of the 17-gauge cryoprobes tested, the probes ablated tissue volumes equivalent to that ablated using the larger, standard 3.4-mm cryoprobe or a configuration of three standard 17-gauge cryoprobes. These novel 17-gauge cryoprobes may facilitate ablation of small and medium-size renal tumors and may have expanded application for percutaneous ablation owing to the decreased risk of hemorrhage.