Decision Making: Thermal Ablation Options for Small Renal Masses

Abstract

Renal cell carcinoma is a relatively common tumor, with an estimated 63,000 new cases being diagnosed in the United States in 2016. Surgery, be it with partial or total nephrectomy, is considered the mainstay of treatment for many patients. However, those patients with small renal masses, typically less than 3 to 4 cm in size who are deemed unsuitable for surgery, may be suitable for percutaneous thermal ablation. We review the various treatment modalities, including radiofrequency ablation, microwave ablation, and cryoablation; discuss the advantages and disadvantages of each method; and review the latest data concerning the performance of the various ablative modalities compared with each other, and compared with surgery.

Keywords: cryoablation; interventional radiology; microwave ablation; radiofrequency ablation; renal cell carcinoma.

Fig. 1

A 72-year-old man who had undergone a previous RFA of a right renal tumor. Approximately 3 years later, a routine surveillance CT was performed ( a ), revealing recurrent tumor (arrow) in the prior ablation zone (arrowhead). He elected to undergo microwave ablation ( b ), with the immediate postprocedure CT showing some small pockets of gas in the right kidney ( c , arrowheads). A follow-up CT 2 months later revealed no evidence of residual or recurrent tumor in the ablation zone ( d , arrowhead).

Fig. 2

A 67-year-old man with a 5-cm renal cell carcinoma in the lower pole of the left kidney. Axial contrast-enhanced CT ( a ) demonstrates a heterogeneously enhancing mass in the lower pole of the left kidney (arrowhead). Cryoablation was performed with three probes ( b ), together with hydrodissection (arrowheads) to protect the nearby bowel. Follow-up CT after 4 weeks revealed no evidence of residual or recurrent disease ( c , arrowhead).

Fig. 3

A 59-year-old man with a small renal cell carcinoma in the left kidney. Axial T1 fat-saturated postcontrast image ( a ) shows a 2.5-cm mass in the left kidney (arrow). Image from the cryoablation procedure ( b ) shows the advancing ice ball (arrowheads), with the ureter protected by the indwelling stent (arrow), through which pyeloperfusion was obtained. Follow-up coronal T1 fat-saturated postcontrast subtracted image ( c ) at 6 weeks shows no evidence of residual tumor (arrow), and no hydronephrosis.

Fig. 4

A 55-year-old woman with a 2.4-cm mass in the left kidney (arrowhead), biopsy-proven papillary renal cell carcinoma ( a ). Prior to cryoablation, hydrodissection was performed with dilute iodinated contrast ( b , arrowhead), to displace the nearby large and small bowel. The ice ball was visualized after 10 minutes ( c , arrowhead), the adjacent structures were successfully protected.