Radiofrequency Ablation, Cryoablation, and Microwave Ablation for the Treatment of Small Renal Masses: Efficacy and Complications

Abstract

Over the last two decades the detection rate of small renal masses has increased, due to improving diagnostic accuracy, and nephron-sparing treatments have become the first-choice curative option for small renal masses. As a minimally invasive alternative, thermal ablation has increased in popularity, offering a good clinical outcome and low recurrence rate. Radiofrequency ablation, Cryoablation, and Microwave ablation are the main ablative techniques. All of them are mostly overlapping in term of cancer specific free survival and outcomes. These techniques require imaging study to assess lesions features and to plan the procedure: US, CT, and both of them together are the leading guidance alternatives. Imaging findings guide the interventional radiologist in assessing the risk of complication and possible residual disease after procedure. The purpose of this review is to compare different ablative modalities and different imaging guides, underlining the effectiveness, outcomes, and complications related to each of them, in order to assist the interventional radiologist in choosing the best option for the patient.

Keywords: ablation; imaging guide; renal cell carcinoma (RCC); small renal masses.

Figure 1

A 41-year-old woman with a biopsy-proven perihilar renal cell carcinoma of the right kidney ((a), arrow). Ureteral double-J stent was positioned right before the procedure to protect the pelvis and urinary tract with continuous refrigerated water flow (b). Precise positioning of the multi-tined RF probe in the right renal hilum mass (c). Contrast-enhanced CT after ablation shows the necrotic area (arrow), without any residual disease or immediate complication (d).

Figure 2

A 67-year-old man with a 34 mm renal cell carcinoma in the left kidney. Axial contrast-enhanced CT (a) demonstrates a heterogeneously enhancing mass (arrow). RF ablation was performed with multitined expandable electrods (b), but post-procedural contrast-enhanced CT revealed areas of enhancement in the mass (arrow) compatible with residual disease (c). A second target positioning was performed to achieve a complete ablation (d). Post-procedural CT shows no enhancement of the ablated lesion and a small hematoma (arrow, (e)). Follow-up CT after 4 weeks revealed no evidence of residual or recurrent disease (arrow) and partial reabsorption of the hematoma (f).

Figure 3

Arterial phase MRI shows a contrast enhancing anterior right kidney mass (arrow) in a 63-year-old man (a). Due to renal mass proximity to hepatic colon flexure, hydrodissection is obtained with 500 mL of glucose solution (double arrow, (b)). RFA is then performed with margin of safety between the probe and the colon (c). A follow-up MRI 2 months later revealed the necrotic mass (arrows) with no evidence of residual or recurrent tumor in the ablation zone: digital subtraction contrast-enhanced MRI (d) and T2w sequence (e).