A Guide to Percutaneous Cryoablation of Renal Masses in Difficult Anatomic Locations

Abstract

Purpose To discuss the pathophysiology of renal cell carcinoma, describe indications for treatment of small renal masses, present technical aspects of percutaneous cryoablation, and highlight adjunctive techniques used to improve success and safety during cryoablation of renal masses in more difficult anatomic locations. Material and Methods A case-based format will be utilized to highlight techniques to improve outcomes in cryoablation of renal masses in difficult anatomic locations. Four major topics will be presented, including maximizing position of the patient, utilization of retrograde pyeloperfusion, using hydrodissection to displace critical structures away from the zone of ablation, and angioplasty balloon interposition to displace adjacent structures from the ablation zone. In addition, combining ablation and embolization in the most difficult anatomic locations will be described. Results Utilizing adjunctive technique during cryoablation leads to successful cryoablation of renal masses in difficult anatomic locations. Placing patients in lateral decubitus position, with the affected side down, results in less aeration of the adjacent lung and reflex increased aeration of the contralateral lung. This allows for improved window to target upper pole renal masses. Retrograde ureteral catheter can be placed to infuse warm saline into the ureter and renal pelvis in an attempt to protect these structures during cryoablation. Hydrodissection can be used to infuse normal saline through a trocar to displace critical structures away from the zone of ablation. Similar to the concept of combining ablation and embolization for treatment of 3 to 5 cm liver tumors, one can combine therapies in an attempt to achieve a synergistic effect. This is particularly useful when there is concern that a complete ablation may not be possible given lesion location in a poor surgical candidate. Conclusions Nephron-sparing therapies have been increasingly utilized in treatment of renal masses. Lesions typically considered more difficult to ablate include central lesions, size larger than 3 cm, upper pole location, endophytic, and adjacent to ureter, colon, or other abdominal organs. Multiple techniques can be used to maximize the likelihood of successful cryoablation of masses in difficult anatomic locations, including hydrodissection, retrograde pyeloperfusion, maximizing patient positioning, and angioplasty balloon interposition.