Percutaneous renal tumor cryoablation with magnetic resonance imaging guidance

Purpose: Cryoablation of small renal tumors has been performed mainly via the laparoscopic or open approach. This study was done to assess the feasibility and safety of performing percutaneous renal tumor cryoablation using interventional magnetic resonance imaging (MRI) for monitoring. Materials and Methods: Patients with radiography documented small renal tumors 4 cm. or less in diameter were offered percutaneous renal tumor cryoablation performed in an interventional MRI unit. Patients received general anesthesia or intravenous sedation and were placed into the interventional MRI unit. Under MRI guidance a 2 or 3 mm. cryoprobe was advanced into the renal mass and the mass was subjected to 3 freeze-thaw cycles at -80 to 70C. Patients were hospitalized overnight for observation. Followup imaging with MRI or computerized tomography and physical examinations were done at 1 week, and 1, 3, 6 and 12 months. Results: Ten men and 10 women 49 to 76 years old (mean age 58) with a total of 22 tumors have been treated, including 1 with bilateral lesions and another with 2 tumors in 1 kidney. Mean tumor diameter was 3 cm. (range 1.8 to 7.0). Two patients with a mass exceeding study entry criteria (5 and 7 cm., respectively) who were not open surgery candidates were treated on a compassionate basis. Average treatment time was 97 minutes (range 56 to 172). To date 1 patient has had evidence of persistent tumor on followup imaging and required re-treatment. The only complication was a superficial wound abscess. Mean followup was 9.1 months (range 3 to 14) with no radiographic evidence of disease recurrence or new tumor development. Conclusions: In this small series of patients percutaneous renal tumor cryoablation was technically feasible with minimal morbidity. At limited followup there appears to be no radiological evidence of new tumor development. Percutaneous cryoablation may prove to be an additional treatment option for small renal tumors.