Intraoperative ultrasonographically guided cryoablation of renal masses: initial experience

The purpose of this study was to evaluate the feasibility of intraoperative ultrasonography to guide cryoablation of renal masses. Renal cryoablation was performed on six patients with solid renal tumors. Under ultrasonographic guidance, cryoprobes measuring 3 mm in diameter were placed into the renal tumor parenchyma or into surrounding normal parenchyma. Intraoperative ultrasonography accurately delineated tumor size, cryoprobe placement, and depth of freezing. An echogenic interface was generated by the marked impedance differences at the junction of the normal renal parenchyma and frozen tissue. In addition, intraoperative ultrasonography identified a total of nine additional lesions in three patients that were not detected by preoperative imaging. These lesions also were treated cryosurgically during the same operation. There were no deaths. The patients have been followed with clinical and laboratory assessments as well as with MR imaging or CT scanning, and all have remained tumor free 3 to 22 months postoperatively. Ultrasonographically guided renal cryoablation is a feasible technique for treating malignant renal tumors while preserving renal parenchyma. Long-term follow-up studies in a larger series of patients are required to determine the true efficacy and safety of this procedure.