Application of contrast-enhanced ultrasonography after radiofrequency ablation for renal cell carcinoma: is it sufficient for assessment of therapeutic response?

Abstract

Despite its limitation of false-positive value, CEUS is potentially effective in assessing the therapeutic response to RFA of RCC.

Imaging of renal cell carcinoma

“…In the setting of focal therapy, CEUS may perform similarly to CT for follow-up imaging, despite CEUS' potential limitation of higher false-positive rates. A study comparing CEUS to CT involving 64 RCC cases did not find a major difference in follow-up results after RFA, shown by the 100% diagnostic concordance between the 2 modalities at 1-month follow-up [18]. The sensitivity, specificity, positive predictive values, and negative predictive values of CEUS for detecting recurrence during follow-up were, respectively, 100%, 96.6%, 50%, and 100% when using CT as the reference imaging method for RFA in this study.…”

Contrast enhanced ultrasound in the evaluation and percutaneous treatment of hepatic and renal tumors

“…After the first year, follow-up was performed every 4 months with CEUS, and CECT or CEMRI every 8 months to reduce costs and the effects of iodinated contrast agents [39]. The reported sensitivity and specificity of CEUS for the evaluation of residual or recurrent RCC are 82.2-100%, and 96.6-100% [39,40,43,44], respectively, with an accuracy of 90.5-98.1% [39,40,43]. The concordance of CEUS with CECT or CEMRI ranges between 80 and 100% [38][39][40][41][42].…”

Contrast-Enhanced Ultrasound-Guided Radiofrequency Ablation of Renal Tumors

“…In practice, UCAs possess a low incidence of side effects and are considered safe for patients, especially those with decreased renal function (4,10,12,13). These patients benefit from the fact that UCAs are not excreted into the urine and therefore not nephrotoxic, a contradistinction to the agents used for CT and magnetic resonance imaging (MRI).…”

“…However, the tissue destruction around the applicator tip limits the achievable ablation size by decreasing the energy deposition through increased electrical impedance. With this in mind, it is suggested for larger tumors (>2 cm) to use either multiple probes simultaneously or a single probe repositioned after each ablation to ensure complete destruction (4,7,9).…”

“…Though RFA is a relatively new treatment for renal tumors and long-term efficacy remains to be seen, the initial data suggest that not only is it safe and well tolerated by patients, but also has a comparable 5-year success rate to that of partial or total nephrectomy (4,5,8). One of its biggest benefits is that the procedure is renal sparing, and RFA is currently used for small tumors, usually less than 5 cm, in patients who are not candidates for surgical removal (7).…”