Radiofrequency ablation for the treatment of renal cell carcinoma: initial experience

Purpose The aim of this retrospective study was to evaluate the clinical value of percutaneous radiofrequency ablation (RFA) for the treatment of renal cell carcinoma (RCC). Materials and Methods In a recent 3 years seven RCCs in six patients were treated by percutaneous RFA. RCC had been diagnosed based on the typical findings by computed tomography and/or magnetic resonance imaging. A cool-tip RF system (Vallylab) was mainly used with a RF2000 generator. The maximum tumor size ranged from 8 to 40 mm in diameter. The follow-up period was 14–36 months after initial RFA treatment. Results Complete disappearance of contrast enhancement during the early arterial phase was noted immediately after each session of percutaneous RFA. Two RCCs ≥ 3 cm in diameter showed tumor recurrence and required re-RFA during the follow-up period. In one patient, retroperitoneal hematoma was observed as a noteworthy complication. Conclusion Despite our limited number of patients, we believe that percutaneous RFA is clinically feasible and can be an alternative treatment of choice for RCC.     

Radiofrequency ablation of renal tumors

Percutaneous thermal ablation is increasingly applied in the therapy of renal tumors. Various techniques are available, allowing a safe and accurate therapy of renal tumors either using hyperthermia such as radiofrequency ablation (RFA), laser-induced thermotherapy (LITT) and microwave ablation (MW) or by hypothermia (cryoablation). As thermal ablation is a minimally invasive and nephron-sparing procedure, it is ideally suited for patients with a single kidney, multiple tumors or contraindications for resective surgery. Although cryotherapy is the most extensively studied technique, RFA has become the most accepted thermal ablation technique over the last years. Modern RFA probes allow ablation volumes between 2 and 5 cm in diameter. A major advantage of RFA is the ability to avoid tract bleeding and tumor seeding by coagulating the puncture channel during RF probe withdrawal. The increasing number of clinical reports on RFA of the kidney show the promising potential of renal RFA for minimally invasive tumor treatment. Due to its technical benefits, RFA seems to be advantageous when compared to cryoablation or laser ablation. However, there are no long-term follow-up or comparative data proving an equal effectiveness to surgery.     

Percutaneous radiofrequency ablation of renal cell carcinoma

Conventional curative therapy for renal cell carcinoma has been open nephrectomy. However, several less invasive and/or nephron-sparing procedures have been developed as alternatives in selected patients. The newest of these therapeutic modalities involves percutaneous image-guided ablation with straight or expandable needle applicators that deposit energy. Radiofrequency ablation is the modality for which there is the largest reported experience with percutaneous application, and involves the use of electrical current to generate frictional heating of tissue. Animal studies confirm the ability of radiofrequency ablation to cause regions of necrosis within normal kidney and in VX2 tumors. Clinically, radiofrequency ablation of small renal cell carcinoma is increasingly being performed in selected patients who are not ideal surgical candidates. Results are excellent for small exophytic tumors, but successful treatment is less likely as tumor size increases or the location becomes more central. Complete treatment of most tumors requires one or more overlapping ablations with the needle electrodes positioned so as to cause necrosis in the entire volume of tumor. The number of overlapping ablations and the position of the needle electrodes vary based on tumor size and geometry. For very large tumors, pre-ablation catheter embolization may enhance the results of ablation by decreasing blood flow and perfusion mediated cooling. Following ablation, imaging with CT or MR is performed to assess the result and to diagnose any residual tumor so that it can be treated. Because the tumor remains in situ, imaging follow-up continues indefinitely. The complication rate of radiofrequency ablation is favorable when compared to surgical techniques. Long-term survival data are not yet available.     

Image-guided radiofrequency ablation of renal cell carcinoma

The incidence of renal cell carcinoma is rising with the increased number of incidental detection of small tumours. During the past few years, percutaneous imaging-guided radiofrequency ablation has evolved as a minimally invasive treatment of small unresectable renal tumours offering reduced patient morbidity and overall health care costs. In radiofrequency ablation, thermal energy is deposited into a targeted tumour by means of a radiofrequency applicator. In recent studies, radiofrequency ablation was shown to be an effective and safe modality for local destruction of renal cell carcinoma. Radiofrequency applicator navigation can be performed via ultrasound, computed tomography or magnetic resonance guidance; however, ultrasound seems less favourable because of the absence of monitoring capabilities during ablation. On-line monitoring of treatment outcome can only be performed with magnetic resonance imaging giving the possibility of eventual applicator repositioning to ablate visible residual tumour tissue. Long-term follow-up is crucial to assess completeness of tumour ablation. New developments in ablation technology and radiological equipment will further increase the indication field for radiofrequency ablation of renal cell carcinoma. Altogether, radiofrequency ablation seems to be a promising new modality for the minimally invasive treatment of renal cell carcinoma, which was demonstrated to exhibit high short-term effectiveness.     

Wide-bore 1.5 Tesla MR imagers for guidance and monitoring of radiofrequency ablation of renal cell carcinoma: initial experience on feasibility

This study was conducted to test and demonstrate the feasibility of magnetic resonance (MR)-guided radiofrequency (RF) ablation of renal cell carcinoma (RCC) using a 1.5 T whole-body scanner equipped with a wide-bore superconductive magnet. Two patients with contrast-enhancing renal masses were treated with multipolar RF ablation (Celon ProSurge). Applicator navigation and near real-time ablation monitoring were performed in a wide-bore 1.5 T scanner using adapted fluoroscopic and diagnostic sequences. In addition to T2-weighted imaging for ablation monitoring, perfusion-weighted images acquired with an arterial spin-labeling technique (FAIR-TrueFISP) were applied. Results were compared to a previous study on 12 patients performed at 0.2 T. Navigation and monitoring of RF ablation using the wide-bore system operating at 1.5 T were clearly improved compared to former experiences on a 0.2 T MR unit. Fluoroscopic and diagnostic images for MR guidance could be acquired with distinctly higher image quality and shorter acquisition time resulting in higher accuracy of applicator placement and shorter treatment time. Spin-labeling perfusion imaging exhibited good image quality, potentially providing additional clinically important information. MR-guided RF ablation of RCC can safely be performed in a 1.5 T wide-bore scanner offering higher image quality, shorter acquisition time, and new monitoring modalities not feasible at 0.2 T.     

Complications of image-guided radiofrequency ablation of renal cell carcinoma: causes, imaging features and prevention methods

Radiofrequency (RF) ablation is an alternative treatment for renal cell carcinoma (RCC) in patients unable to undergo surgery. Although RF ablation has a low complication rate because of its minimally invasive nature, unintended heat may be conducted by several critical organs during ablation procedures, leading to a variety of complications. Major complications that usually require treatment include bowel injury, ureteral injury, massive bleeding and residual or recurrent tumour. Minor complications that may require only observation include pain, haematoma, haematuria, neuromuscular injury, pneumothorax, infarction and inflammatory tract mass. The most common cause of complications is the tumour’s proximity to neighbouring organs. In addition, careless electrode manipulation and the patient’s comorbidities may also lead to complications. To avoid many of these complications, the distance between the tumour and neighbouring organs should be widened using methods such as changing the patient’s position, using the RF electrode as a lever and hydrodissection. Furthermore, carefully manipulating the RF electrode and assessing the patient’s general condition help to prevent complications. In this review, we discuss the complications resulting from RF ablation of RCC with an emphasis on causes, imaging features and prevention methods.     

Radiofrequency ablation of renal cell carcinoma

Small renal cell carcinomas of less than 4 cm diameter have been detected increasingly in asymptomatic patients because of the widespread use of cross-sectional imaging. Radical or partial nephrectomy is generally considered the reference for the treatment of a solitary renal cell carcinoma. However, for those patients who are not candidates for surgery, minimally invasive procedures may be desirable. Although percutaneous radiofrequency ablation for the treatment of renal cell carcinoma is a recent innovation, the results of preliminary clinical series and animal studies are encouraging, and show it to be technically feasible with minimal morbidity. In this article, we review the technique, indications, imaging findings, as well as the results of clinical and animal studies of radiofrequency ablation for the treatment of renal cell carcinoma.     

Image-guided radiofrequency ablation of Bosniak category III or IV cystic renal tumors: initial clinical experience

The purpose of this study was to assess the efficacy of image-guided radiofrequency (RF) ablation of cystic renal tumors. Between November 2005 and August 2007, computed tomography (CT) or ultrasound-guided RF ablation was performed in nine patients with 14 Bosniak category III (n = 5) or IV (n = 9) cystic renal tumors using an internally cooled RF ablation system. We evaluated the number of sessions, cycles and duration of energy application, treatment results, lesion size change, and complications. Together the cystic renal tumors required 15 sessions and 23 cycles of energy application. The duration of energy application per one tumor ablation ranged from 1 to 12 min (mean 6 min). The last follow-up CT indicated complete coagulation of 14/14 (100%) lesions. None of these tumors had recurred within 1-19 months (mean 8 months). The maximum diameter of the cystic renal tumors was significantly reduced from 2.5 +/- 0.6 cm before ablation to 1.7 +/- 0.7 cm at the last follow-up CT (P < 0.01). Complications were pneumothorax (n = 2), inguinal paresthesia (n = 1), and arteriovenous fistula (n = 1). Image-guided RF ablation is an effective treatment for Bosniak category III or IV cystic renal tumors, which might need relatively shorter duration of energy application than purely solid renal tumors of the same size.     

Percutaneous radiofrequency ablation of renal cell carcinomas in patients with solitary kidney: 6 years experience

Objective

In this study we attempt to present our clinical experience in RFA under CT-guidance, in patients with renal cell carcinoma in a solitary kidney.

Material and Method

Between October 2000 and June 2005, 18 patients with solitary kidney and renal cell carcinoma underwent percutaneous CT-guided radiofrequency ablation in our institution. Tumors diameter ranged from 1 to 7 cm and there was no evidence of spread beyond the kidney. The RFA-system used was with expandable needle electrode (7 or 9 arrays). Technical success, recurrence and survival rate and complications were accessed. Patients were available for clinical and laboratory evaluation at a mean follow-up time of 31.2 months (range: 12–72 months).

Results

In all cases the electrode was successfully placed at the lesion. The 18 tumors were treated with totally 24 RFA sessions. In small (1–3 cm) exophytic tumors technical success was 85.7%. Residual disease was totally seen in 6/18 tumors which required a 2nd RFA session. The recurrence rate was 11.1% but no recurrence was noticed in tumors less than 3 cm in diameter. No major complications were observed. Serum creatinine values were normal in 17/18 patients till the 3rd-month follow-up. Survival ranged from 12 to 72 months.

Conclusion

RFA is an acceptable alternative for patients with small RCCs in a solitary kidney, which are not ideal candidates for surgical resection as their renal function must be preserved. They have an immediate solution to their clinical problem, under a minimally invasive therapy with no serious complications.     

Transarterial embolization (TAE) as add-on to percutaneous radiofrequency ablation (RFA) for the treatment of renal tumors: Review of the literature,overview of state-of-the-art embolization materials and further perspective of advanced image-guided tumor ablation

Percutaneous radiofrequency ablation (RFA) for the treatment of stage I renal cell carcinoma has recently gained significant attention as the now available long-term and controlled data demonstrate that RFA can result in disease-free and cancer-specific survival comparable with partial and/or radical nephrectomy. In the non-controlled single center trials, however, the rates of treatment failure vary. Operator experience and ablation technique may explain some of the different outcomes. In the controlled trials, a major limitation is the lack of adequate randomization. In case reports, original series and overview articles, transarterial embolization (TAE) before percutaneous RFA was promising to increase tumor control and to reduce complications. The purpose of this study was to systematically review the literature on TAE as add-on to percutaneous RFA for renal tumors. Specific data regarding technique, tumor and patient characteristics as well as technical, clinical and oncologic outcomes have been analyzed. Additionally, an overview of state-of-the-art embolization materials and the radiological perspective of advanced image-guided tumor ablation (TA) will be discussed. In conclusion, TAE as add-on to percutaneous RFA is feasible and very effective and safe for the treatment of T1a tumors in difficult locations and T1b tumors. Advanced radiological techniques and technologies such as microwave ablation, innovative embolization materials and software-based solutions are now available, or will be available in the near future, to reduce the limitations of bland RFA. Clinical implementation is extremely important for performing image-guided TA as a highly standardized effective procedure even in the most challenging cases of localized renal tumors.     

Dual-energy CT in assessing therapeutic response to radiofrequency ablation of renal cell carcinomas

Purpose

To investigate the utility of dual-energy (DE) CT using virtual noncontrast (VNC) and iodine overlay (IO) images to assess therapeutic response to radiofrequency ablation (RFA) for renal cell carcinomas (RCCs).

Materials and methods

In this institutional review board-approved study (with waiver of informed consent), 47 patients with RCCs that underwent DECT after RFA were enrolled in this study. DECT protocols included true noncontrast (TNC), linearly blended DE corticomedullary and late nephrographic phase imaging. Two types of VNC and IO images were derived from corticomedullary and late nephrographic phases, respectively. To predict local tumor progression at RFA site, linearly blended and IO images were analyzed both qualitatively and quantitatively. Contrast-to-noise ratios (CNR) of renal cortex-to-RFA zones were calculated. The overall imaging quality of VNC images was compared with TNC images.

Results

The IO images from corticomedullary and late nephrographic phases showed excellent diagnostic performance (each sensitivity 100% and each specificity 91.5%) for predicting local tumor progression. The degree of enhancement of local tumor progression was not significantly different between linearly blended and IO images (P > 0.05). The mean CT numbers were not significantly different between TNC and VNC images (P > 0.05). In renal cortex-to-RFA site, CNR between linearly blended and IO images was not significantly different (P > 0.05). The VNC imaging quality from the two phases was given a good rating.

Conclusion

VNC and IO images from DECT may allow acceptable diagnostic performance with less radiation exposure as a follow-up imaging tool after RFA for RCC, compared to the linearly blended CT images.     

胰腺癌术中射频消融治疗效果及安全性分析

 目的 评估术中射频消融治疗不能切除胰腺癌病例的有效性和安全性.方法 对23例不能切除的胰腺癌病例实施术中射频消融,观察患者手术前后疼痛、黄疸、CA19-9、CEA、淀粉酶、影像学改变及术后并发症和生存率.结果 术后87.05%的患者腹痛缓解,92%黄疸消退,CA19-9、CEA明显下降,淀粉酶一过性增高,术后CT示病灶血供减少.并发出血6例,胰瘘6例,均治愈出院.所有患者均获得随访,存活12个月以上12例,最长者已达42个月,生活质量较好.结论 术中射频消融治疗不能切除的胰腺癌安全有效.     

Spontaneous regression of pulmonary and adrenal metastases following percutaneous radiofrequency ablation of a recurrent renal cell carcinoma

The spontaneous regression of metastatic lesions from renal cell carcinoma (RCC) is extremely rare, but may be encountered following cytoreductive treatments. We report a case of a recurrent RCC with multiple metastatic lesions which spontaneously regressed after undergoing radiofrequency ablation of the renal tumor.     

Radiofrequency ablation of hepatocellular carcinoma: Current status

Ablation therapy is one of the best curative treatment options for malignant liver tumors, and can be an alternative to resection. Radiofrequency ablation (RFA) of primary and secondary liver cancers can be performed safely using percutaneous, laparoscopic, or open surgical techniques, and RFA has markedly changed the treatment strategy for small hepatocellular carcinoma (HCC). Percutaneous RFA can achieve the same overall and disease-free survival as surgical resection for patients with small HCC. The use of a laparoscopic or open approach allows repeated placements of RFA electrodes at multiple sites to ablate larger tumors. RFA combined with transcatheter arterial chemoembolization will make the treatment of larger tumors a clinically viable treatment alternative. However, an accurate evaluation of treatment response is very important to secure successful RFA therapy. Since a sufficient safety margin (at least 0.5 cm) can prevent local tumor recurrences, an accurate evaluation of treatment response is very important to secure successful RFA therapy. To minimize complications of RFA, clinicians should be familiar with the imaging features of each type of complication. Appropriate management of complications is essential for successful RFA treatment.     

Radio-frequency ablation of renal cell carcinoma: early clinical experience

PURPOSE: To report the authors' early experience with radio-frequency (RF) ablation of renal cell carcinoma. MATERIALS AND METHODS: Twenty-four percutaneous RF ablation treatments for nine tumors were performed in eight patients with renal cell carcinoma. Indications included coexistent morbidity, previous surgery, or solitary kidney in patients with a life expectancy shorter than 10 years. Smaller (3 cm) and/or central lesions (n = 6) were treated with cluster or multiple electrodes. Patients returned for a second treatment when follow-up imaging depicted tumor enhancement. Follow-up imaging was performed at 1 and 3 months and then at 6-month intervals, with a mean follow-up of 10.3 months. Seven patients were alive at least 6 months after their initial treatment. RESULTS: All five exophytic tumors were free of enhancement. One of three central tumors was free of enhancement. One tumor had both central and exophytic components and was free of enhancement. Three tumors were 3 cm or smaller and free of enhancement. Of the six tumors larger than 3 cm, four were free of enhancement. CONCLUSION: Percutaneous RF ablation is a promising treatment for select patients with renal cell carcinoma. The ultimate role of this modality will continue to evolve and warrants further study.     

Radiofrequency thermal ablation of liver tumors

Radiofrequency ablation (RFA) of liver tumors was first proposed in 1990. New technologies enable us to produce liver thermal lesions of approximately 3–3.5 cm in diameter; RFA has consequently become an emerging percutaneous therapeutic option both for small hepatocellular carcinoma (HCC) and for non-resectable liver metastases, mainly from colorectal cancer. New devices (for example, triplet of cooled needles, wet needles) and combined therapies (tumor ischemia and RFA) have made it possible to treat large tumors. RFA can be carried out by a percutaneous, laparoscopic or laparotomic approach. Percutaneous RFA can be performed with local anaesthesia and mild sedation; deep sedation or general anaesthesia are also used. The guidance system is generally represented by ultrasound. CT or MR examinations are the more sensitive tests for assessing therapeutic results. The series of patients treated with RFA allow the technique to be considered as effective and safe, achieving a relatively high rate of cure in properly selected cases; it should be classified as curative/effective treatment for HCC, replacing percutaneous ethanol injection. The complication rate of RFA is low but not negligible; key elements in a strategy to minimize them are identified.     

射频消融治疗肾癌现状

近年来射频消融日益广泛应用于肾癌治疗,随着操作技术的不断发展,已在临床上取得显著的近期疗效,具有微创、安全、操作方便、并发症轻、患者痛苦少等特点。其未来发展的关键在于改进电极针,提高射频技术,联合c其他疗法等以提高疗效,并建立更合理的包括影像检查技术在内的疗效评价标准。     

Radiofrequency Ablation of Renal Tumors: Four-Year Follow-Up Results in 47 Patients

Objective

To retrospectively evaluate the intermediate results of radiofrequency ablation (RFA) of small renal masses (SRMs).

Materials and Methods

Percutaneous or laparoscopic RFA was performed on 48 renal tumors in 47 patients. The follow-up studies included a physical examination, chest radiography, creatinine level, and contrast-enhanced CT or MRI. To confirm the pathologic criteria of complete ablation, 35 patients underwent a follow-up biopsy. Recurrence was defined as contrast enhancement on imaging studies after 3 months, lesion growth at subsequent imaging, or viable cancer cells on follow-up biopsy.

Results

Technical success was achieved in 43 (89.6%) of 48 renal tumors. The mean tumor size was 2.3 cm and the mean follow-up period was 49.6 months. Repeated RFA was necessary in 5 tumors due to incomplete ablation. The overall complication rate was 35.8%, of which 96.2% were mild complications. Serum creatinine levels at 12 months after RFA did not differ from those before RFA (1.28 vs. 1.36 mg/dL). Four patients were found to have recurrence at various follow-up intervals, and distant metastasis was not found in any cases.

Conclusion

RFA appears to be a useful treatment for selected patients with SRMs. Our 4-year follow-up results disclose an excellent therapeutic outcome with RFA, while achieving effective local tumor control.     

Using an electrode as a lever to increase the distance between renal cell carcinoma and bowel during CT-guided radiofrequency ablation

The technique of using an electrode as a lever to increase the distance between renal cell carcinoma (RCC) and bowel during CT-guided radiofrequency ablation (RFA) is described. CT-guided percutaneous RFA was performed in two patients with two RCCs, which were in close proximity to the adjacent bowel. A sterile drape was placed on the electrode handle following appropriate electrode placement within the tumor in order to displace the kidney upward and to widen the distance to >5 mm between RCC and bowel (RCC-to-bowel distance). In patient 1, the RCC-to-bowel distance increased from 3 mm to 6 mm; in patient 2, from less than 2 mm to 6 mm. Follow-up CT performed 1 month after RFA demonstrated not only complete ablation of the two RCCs but also no thermal injury to the bowel adjacent to the tumors. In conclusion, an electrode might be used as a lever to increase RCC-to-bowel distance during CT-guided RFA by placing a sterile drape on it.     

Radiofrequency ablation of large size liver tumours using novel plan-parallel expandable bipolar electrodes: Initial clinical experience

Purpose

Although radiofrequency ablation (RFA) is a promising method for local treatment of liver malignancies, with conventional monopolar systems recurrence rates for large size tumours (≥3.5 cm) remain high. The objective of this study was to evaluate the safety, feasibility and local effectiveness of a novel bipolar plan-parallel expandable system for these larger tumours.

Methods and materials

Eight consecutive patients with either unresectable colorectal liver metastases (CRLM in 6 patients), carcinoid liver metastases (1 patient) and hepatocellular carcinoma (HCC in 1 patient) of ≥3.5 cm were treated with bipolar RFA during laparotomy with ultrasound guidance. Early and late, major and minor complications were recorded. Local success was determined on 3-8 month follow-up CT scans of the upper abdomen.

Results

Nine CRLM, one carcinoid liver metastases and one HCC (3.5-6.6 cm) were ablated with bipolar RFA. Average ablation time was 16 min (range 6-29 min.). Two patients developed a liver abscess which required re-laparotomy. In both cases bowel surgery during the same session probably caused bacterial spill. There were no mortalities. The patients were released from hospital between 5 and 29 days after the procedure (median 12 days). The 6-12 month follow-up PET-CT scans showed signs for marginal RFA-site tumour recurrence in three patients with CRLM (3/11 lesions).

Conclusion

Preliminary results suggest bipolar RFA to be a reasonably safe, fast and feasible technique which seems to improve local control for large size hepatic tumour ablations.