Radiofrequency ablation of renal cell carcinoma

Radioactive seed localization of renal cell carcinoma in a patient with Von Hippel-Lindau disease

This report describes the case of a patient, who had successful radioactive seed localization (RSL) performed to improve the identification and excision of a renal cell carcinoma. RSL is a new method of preoperative localization, which can ease the surgical procedure, minimize tissue trauma, and ultimately benefit the patient.

Radiofrequency thermal ablation of renal tumors

Percutaneous radiofrequency ablation (PRFA) of renal malignancies is currently a therapeutic option for patients who are not able to undergo surgery. Some authors consider PRFA as the therapeutic standard in the treatment of renal neoplasms in non-operable patients due to comorbid conditions and in patients with mild-moderate renal failure, to preserve residual renal functionality. The use of PRFA has become more and more widespread due to a rise in the incidental detection of renal cell carcinomas with the ever-increasing use of Imaging for the study of abdominal diseases. Clinical studies indicate that RF ablation is an effective therapy with a low level of risk of complications, which provides good results in selected patients over short and medium term periods of time, however up to now few long-term studies have been carried out which can confirm the effectiveness of PRFA.

Electrolysis - a new method of renal ablation?

OBJECTIVE

• To present a novel method of renal ablation using direct current electrolysis, using a porcine model to assess the safety and efficacy of the technique.

MATERIALS AND METHODS

• In all, 20 anaesthetised pigs were used, after receiving ethical approval. The pigs were housed and managed in accordance with Institute of Medical and Veterinary Science guidelines. • A single 6 F catheter incorporating cathode and anode was inserted directly into the renal parenchyma via a loin incision. A direct current of 100 mA was applied for varying times. • Several treatments were performed in each pig and a total of 72 treatments were analysed. • The pigs were recovered and observed for 3 days with an analysis of electrolytes and creatinine after ablation. The pigs were humanely killed at 3 days and the kidneys submitted for histological analysis.

RESULTS

• Complete tissue destruction was seen in the area of kidney treated with no viable cells. • A sharp line of demarcation was noted between normal renal parenchyma and the area of coagulative necrosis. The area of tissue ablation was reliably predicted from the duration of application of the electrolytic current. • One pig developed a secondary haemorrhage.

CONCLUSIONS

• Renal electrolysis is a new method of focal renal ablation. The procedure may be carried out using a fine ablation catheter (6 F) allowing for the development of minimal intervention treatment of small renal masses. • This study shows the technique to be effective and safe. As with other renal ablative techniques there is a small risk of postoperative haemorrhage.

Contrast-enhanced ultrasonography evaluation of radiofrequency ablation of the prostate: a canine model

BACKGROUND AND PURPOSE

Currently, there is no reliable method of monitoring the propagation of radiofrequency lesions in real time. We report our animal experience using contrast-enhanced ultrasonography (CEUS) to evaluate the lesion produced by radiofrequency ablation (RFA) in a canine model and investigate the feasibility to predict these lesions.

MATERIALS AND METHODS

Five male beagle dogs underwent RFA of the prostate. Radiofrequency was delivered under transrectal ultrasonography guidance. We created a lesion in the right and left lateral lobes of canine prostate. Post-RFA lesion size was measured with conventional ultrasonography and contrast-enhanced low-mechanical index perfusion imaging (ESAOTE DU8, CnTI) with a second-generation contrast agent (Sonovue). The prostates were assessed for a contrast void corresponding to the ablated tissue. All dogs were then immediately killed, and the prostates were harvested for pathologic analysis. The gross RFA lesions were measured to compare lesion size with that measured using CEUS.

RESULTS

The RFA lesions could not be imaged accurately in real time with conventional grayscale or power Doppler sonography. With CEUS imaging, a clear lesion was identified at the site of each RFA application. As measured by CEUS, the lesions volume averaged 1.30 +/- 0.50 cm(3), compared with 1.32 +/- 0.53 cm(3) by measurement in the gross specimen (p = 0.324).

CONCLUSIONS

CEUS appears to be an accurate modality for immediate monitoring of RFA procedure. Further study is necessary to assess the clinical utility of CEUS for monitoring RFA of localized prostate cancer.

Radiofrequency ablation for renal tumors: our experience

OBJECTIVES

To report our results of percutaneous radiofrequency ablation (RFA) for renal tumors and to assess predictors of therapeutic efficacy.

METHODS

Forty patients (median age 73 years) with renal tumors were treated with RFA under local or epidural anesthesia. All of them had high surgical risk or refused radical surgery. Tumors were punctured percutaneously using the Radionics Cool-tip RF System under computed tomography or ultrasonographic guidance. Median tumor diameter was 24 mm. After RFA, contrast-enhanced computed tomography or magnetic resonance imaging was performed within 1 month. Complete response (CR) was defined as no enhancement inside the tumor. Factors related to the outcome and to renal function were assessed.

RESULTS

Median follow up was 16 months. CR was observed in 34 cases (85.0%). A significant difference in CR rate was observed between tumors < or =30 mm and those >30 mm. Outcomes tended to be better for tumors in the mid to lower kidney, and those away from the renal hilum. Recurrence was observed in one case (2.9%), but a CR was obtained again by additional RFA. Out of a total of 77 RFA procedures, complications occurred in only three cases (3.9%), and conservative treatment was possible in all cases. Serum creatinine levels 3 months after RFA did not differ from those before RFA.

CONCLUSIONS

Percutaneous RFA is a safe and effective treatment for small renal tumors in patients with high surgical risk or who refuse radical surgery.