Percutaneous radiofrequency ablation of nodal metastases

We report our experience with percutaneous image-guided radiofrequency (RF) ablation to treat isolated nodal metastases. Four patients underwent image-guided percutaneous RF ablation of metastatic disease involving retrocrural nodes, retroperitoneal nodes, or pelvic nodes. Coagulation necrosis was achieved in all cases.     

Radiofrequency ablation of pulmonary tumors

The development of image-guided percutaneous techniques for local tumor ablation has been one of the major advances in the treatment of solid tumors. Among these methods, radiofrequency (RF) ablation is currently established as the primary ablative modality at most institutions. RF ablation is accepted as the best therapeutic choice for patients with early-stage hepatocellular carcinoma when liver transplantation or surgical resection are not suitable options and is considered as a viable alternate to surgery for inoperable patients with limited hepatic metastatic disease, especially from colorectal cancer. Recently, RF ablation has been demonstrated to be a safe and valuable treatment option for patients with unresectable or medically inoperable lung malignancies. Resection should remain the standard therapy for non-small cell lung cancer (NSCLC) but RF ablation may be better than conventional external-beam radiation for the treatment of the high-risk individual with NSCLC. Initial favourable outcomes encourage combining radiotherapy and RF ablation, especially for treating larger tumors. In the setting of colorectal cancer lung metastases, survival rates provided by RF ablation in selected patients, are substantially higher than those obtained with any chemotherapy regimens and provide indirect evidence that RF ablation therapy improves survival in patients with limited lung metastatic disease.     

Percutaneous radiofrequency ablation of hepatic colorectal metastases: technique, indications, results, and new promises

Surgical resection is the standard of care for colorectal metastases isolated to the liver. However, only 10-25% of the patients are eligible for resection because of extent and location of the disease in the liver or concurrent medical conditions. Image-guided radiofrequency (RF) ablation is a minimally invasive technique that is emerging as a viable alternate treatment of nonsurgical patients with limited hepatic metastatic disease. Several series have shown that RF ablation can result in complete tumor eradication in properly selected candidates and have provided indirect evidence that the treatment improves survival. In a recent multicenter trial including 423 patients, overall survival of RF-ablation treated patients reached 47% at 3 years and 24% at 5 years. RF ablation technology is undergoing continuous improvement, and its clinical application has been successfully expanded to the treatment of colorectal metastases to the lung. Randomized trials comparing RF ablation with either surgical resection or chemotherapy protocols, however, are still missing. In this article, we review technique, indications, clinical results, and future prospects of RF ablation in the therapeutic management of metastatic colorectal cancer patients.     

Actual role of radiofrequency ablation of liver metastases

The liver is, second only to lymph nodes, the most common site for metastatic disease irrespective of the primary tumour. More than 50% of all patients with malignant diseases will develop liver metastases with a significant morbidity and mortality. Although the surgical resection leads to an improved survival in patients with colorectal metastases, only approximately 20% of patients are eligible for surgery. Thermal ablation and especially radiofrequency ablation emerge as an important additional therapy modality for the treatment of liver metastases. RF ablation shows a benefit in life expectancy and may lead in a selected patient group to cure. Percutaneous RF ablation appears safer (versus cryotherapy), easier (versus laser), and more effective (versus ethanol instillation and transarterial chemoembolisation) compared with other minimally invasive procedures. RF ablation can be performed by a percutaneous, laparoscopical or laparotomic approach, and may be potentially combined with chemotherapy and surgery. At present ideal candidates have tumours with a maximum diameter less than 3.5 cm. An untreatable primary tumour or a systemic disease represents contraindications for performing local therapies. Permanent technical improvements of thermal ablation devices and a better integration of thermal ablation in the overall patient care may lead to prognosis improvement in patients with liver metastases.     

Radiofrequency ablation therapy of remnant colorectal liver metastases after a course of hepatic arterial infusion chemotherapy

The present study evaluated the feasibility of combined therapy employing repeated hepatic arterial infusion chemotherapy (HAIC) via a port-catheter system and radiofrequency (RF) ablation for unresectable metastatic liver cancer from the colo-rectum. RF ablation was performed for six patients with liver malignancies that had been well controlled and had decreased in number and size with repeated HAIC. After RF ablation subsequent to repeated HAIC, all six patients had stable disease or complete or partial remission as documented by follow-up contrast-enhanced computed tomographic (CT) imaging. Fluorodeoxyglucose positron emission tomography (18F) showed complete response in all ablated lesions. In conclusion, RF ablation after a course of HAIC achieved complete necrosis in residual lesions after HAIC therapy.     

Radiofrequency ablation of liver cancer

The development of image-guided percutaneous techniques for local tumor ablation has been one of the major advances in the treatment of liver malignancies. Over the past two decades, several methods for chemical or thermal tumor destruction have been clinically tested. Among these methods, radiofrequency (RF) ablation is currently established as the primary ablative modality at most institutions. RF ablation is accepted as the best therapeutic choice for patients with early stage hepatocellular carcinoma (HCC) when liver transplantation or surgical resection is not suitable options. In addition, RF ablation is emerging as a viable alternative to surgery for inoperable patients with limited hepatic metastatic disease, especially from colorectal cancer. Several series have shown that RF ablation can result in complete tumor eradication in properly selected candidates, and have provided indirect evidence that the treatment improves survival. In this article, we review technique, indications, and clinical results of percutaneous RF ablation in the treatment of HCC and colorectal hepatic metastases.     

Radiofrequenzablation von Lebermetastasen

The liver is the second only to lymph nodes as the most common site of metastatic disease irrespective of the primary tumor. Up to 50% of all patients with malignant diseases will develop liver metastases with a significant morbidity and mortality. Although the surgical resection leads to an improvement of the survival time, only approximately 20% of the patients are eligible for surgical intervention. Radiofrequency (RF) ablation represents one of the most important alternatives as well as complementary methods for the therapy of liver metastases. RF ablation can lead in a selected patient group to a palliation or to an increased life expectancy. RF ablation appears either safer (vs. cryotherapy) or easier (vs. laser) or more effective (percutaneous ethanol instillation [PEI], transarterial chemoembolisation [TACE]) in comparison with other minimal invasive procedures. RF ablation can be performed percutaneously, laparoscopically or intraoperatively and may be combined with chemotherapy as well as with surgical resection. Permanent technical improvements of RF systems, a better understanding of the underlying electrophysiological principles and an interdisciplinary approach will lead to a prognosis improvement in patients with liver metastases.     

射频消融治疗椎旁软组织转移性肿瘤的初步应用

目的 探讨经皮射频消融(RFA)治疗椎旁软组织转移瘤方法及可行性.方法 应用1500X型多极温控射频发生器,对3例椎旁转移瘤患者予以RFA治疗.在DSA引导下,穿刺入椎旁转移瘤内,插入射频电极针,射频功率设定为30～80 W.消融温度设定为60～90℃,消融治疗时间8～15 min.结果 3例患者术前疼痛症状均有不同程度缓解,无感染、针道转移等并发症.结论 经皮RFA具有安全、微创、操作简便的特点,为治疗椎旁软组织转移性肿瘤提供了一种新的治疗手段,其远期效果需进一步观察.     

Percutaneous treatment of liver tumors with an adapted probe for cooled-tip,impedance-controlled radio-frequency ablation under open-magnet MR guidance: initial results

Percutaneous radio-frequency (RF) ablation of liver tumors is usually performed under guidance of real-time US, but some tumor nodules in some patients cannot be adequately visualized with this technique. We report our preliminary results with an MR-compatible, internally perfused 17-G RF probe adapted to a standard RF generator for impedance-controlled RF ablation under MR guidance. Following initial testing of the probe for MR compatibility, artifacts and macroscopic effects on an ex vivo pig liver, four patients with eight neoplastic liver nodules (five metastatic and three primary), which could not be properly targeted by US, were treated with the cooled-tip technique under MRI guidance in an open 0.23-T magnet. Metallic artifacts produced by the probe were useful for accurate placement and did not interfere with MRI monitoring at the end of the procedure. Based on imaging findings, the immediate result of RF was considered adequate in all instances. Local recurrence occurred in one instance after 6 months, requiring repeat treatment. No adverse effects were noted. Initial experience suggests that the probe we used allows to perform impedance-controlled cooled-tip RF ablation of liver tumors under open-magnet MR guidance. Electronic Publication     

Radiofrequency thermal ablation of a metastatic lung nodule

Pulmonary metastases are a common finding in patients with colonic adenocarcinoma. We report the treatment of a metastatic lung nodule with radiofrequency (RF) ablation under CT guidance. This case illustrates the use of RF ablation in a patient in whom surgical resection was no longer possible and where chemotherapy was unlikely to produce benefit. This technique may offer a viable method of cytoreduction when other treatments have not succeeded.     

Effectiveness of Radiofrequency Ablation in the Treatment of Painful Osseous Metastases: A Correlation Meta-Analysis with Machine Learning Cluster Identification

A systematic review and meta-analysis of pain response after radiofrequency (RF) ablation over time for osseous metastases was conducted in 2019. Analysis used a random-effects model with GOSH plots and meta-regression. Fourteen studies comprising 426 patients, most with recalcitrant pain, were identified. Median pain reduction after RF ablation was 67% over median follow-up of 24 weeks (R² = −.66, 95% confidence interval −0.76 to −0.55, I² = 71.24%, fail-safe N = 875) with 44% pain reduction within 1 week. A low-heterogeneity subgroup was identified with median pain reduction after RF ablation of 70% over 12 weeks (R² = −.75, 95% confidence interval −0.80 to −0.70, I² = 2.66%, fail-safe N = 910). Addition of cementoplasty after RF ablation did not significantly affect pain scores. Primary tumor type and tumor size did not significantly affect pain scores. A particular, positive association between pain after RF ablation and axial tumors was identified, implying possible increased palliative effects for RF ablation on axial over appendicular lesions. RF ablation is a useful palliative therapy for osseous metastases, particularly in patients with recalcitrant pain.     

Percutane Image-Guided Cryoablation of Painful Osseous Metastases: A Retrospective Single-Center Review

PurposePainful osseous metastases are a common problem in patients with malignancy, and they can be associated with significant morbidity owing to immobility, pain, pathologic fracture, or neurovascular compromise or all of these. We retrospectively evaluated pain levels and tumor enhancement in patients who underwent palliative percutaneous cryoablation for painful bone metastasis.MethodsIn this institutional review board-approved, health insurance portability and accountability act-compliant study, we retrospectively searched our department׳s picture archiving system for patients who underwent computed tomography (CT)-guided percutaneous cryoablation for treatment of painful metastatic osseous disease over a 6-year period (1/1/2005-12/31/2011). The preprocedure and postprocedure images and imaging reports, primary tumor type, CT-guided cryoablation procedure details, treated tumor response, immediate and 3-month postprocedure complications, reported pain response to cryoablation, postprocedural tumor imaging characteristics, and imaging response of noncryoablated systemically treated metastatic lesions were reviewed in patients with metastatic osseous disease who underwent cryoablation.ResultsAll 16 patients reported improvement in pain within 1 week after the procedure and at 3-month clinical follow-up. A total of 6.2% had tumor growth and 93.8% had tumor arrest or shrinkage on follow-up CT, although all study patients had progression of noncryoablated metastases at other sites despite systemic therapy. A total of 62.5% of patients with posttreatment contrasted CT demonstrated marginal enhancement at the ablation site, although only single patient had interval growth.ConclusionMost of our patients had tumor arrest or shrinkage on follow-up imaging, despite progression of noncryoablated metastases treated with preprocedure and postprocedure systemic therapy. Radiation therapy, chemotherapy, and analgesics have a moderate failure rate and require repeat treatments where quality of life is the foremost objective. CT-guided cryoablation is a safe palliative treatment to reduce pain in patients with painful osseous metastatic disease, achieve effective local tumor control, and in some cases, provide a curative option for a target lesion.     

Radiofrequency Ablation for the Palliative Treatment of Bone Metastases: Outcomes from the Multicenter OsteoCool Tumor Ablation Post-Market Study (OPuS One Study) in 100 Patients

PurposeTo evaluate the effectiveness of radiofrequency (RF) ablation as measured by change in worst pain score from baseline to 3 mo after RF ablation for the palliative treatment of painful bone metastases.Materials and MethodsOne hundred patients (mean age, 64.6 y) underwent RF ablation for metastatic bone disease and were followed up to 6 mo. Subjects’ pain and quality of life were measured before RF ablation and postoperatively by using the Brief Pain Index and European Quality of Life questionnaires. Opioid agent use and device-, procedure-, and/or therapy-related adverse events (AEs) were collected.ResultsEighty-seven patients were treated for tumors involving the thoracolumbar spine and 13 for tumors located in the pelvis and/or sacrum. All ablations were technically successful, and 97% were followed by cementoplasty. Mean worst pain score decreased from 8.2 ± 1.7 at baseline to 3.5 ± 3.2 at 6 mo (n = 22; P < 0.0001 for all visits). Subjects experienced significant improvement for all visits in average pain (P < .0001), pain interference (P < .0001), and quality of life (P < .003). Four AEs were reported, of which 2 resulted in hospitalization for pneumonia and respiratory failure. All 30 deaths reported during the study were attributed to the underlying malignancy and not related to the study procedure.ConclusionsResults from this study show rapid (within 3 d) and statistically significant pain improvement with sustained long-term relief through 6 mo in patients treated with RF ablation for metastatic bone disease.     

Radiofrequency thermal ablation of a metastatic lung nodule

European Radiology - Pulmonary metastases are a common finding in patients with colonic adenocarcinoma. We report the treatment of a metastatic lung nodule with radiofrequency (RF) ablation under...     

Repeat radiofrequency ablation for local progression of lung tumors: does it have a role in local tumor control?

PURPOSE: To retrospectively evaluate the role of repeat radiofrequency (RF) ablation for local progression of lung tumors in local tumor control. MATERIALS AND METHODS: From June 2001 to February 2007, the authors treated 797 lung tumors (primary lung cancer, n=66; metastatic lung neoplasm, n=731; mean tumor size, 1.7 cm) in 295 patients with RF ablation. After RF ablation, patients were followed-up with contrast-enhanced chest computed tomography at 1, 3, 6, 9, and 12 months and thereafter at 6-month intervals. Local progression was observed in 117 of the 797 lung tumors. Fifty repeat RF ablation sessions were performed for 56 tumors (primary lung cancer, n=9; metastatic lung neoplasm, n=47; mean tumor size, 2.7 cm) in 46 patients (33 men, 13 women; mean age, 59.6 years). Repeat RF ablation was not performed for the remaining 61 locally progressing tumors because it was not presumed to provide survival benefit. For all 797 tumors, the overall primary and secondary technique effectiveness rates (TERs) after the first RF ablation were compared with each other. To determine the risk factors for local control with repeat RF ablation, multiple variables were analyzed. Next, local control with repeat RF ablation was evaluated for tumors with and tumors without risk factors. RESULTS: The overall secondary TERs were significantly higher than the overall primary TERs (P<.00001). Tumor size of at least 2 cm at the first RF ablation (P=.045) and contact with bronchi (P=.045) or vessels (P=.048) were risk factors for local control with repeat RF ablation. The secondary TERs after the first RF ablation were 94% at 1 year, 68% at 2 years, and 55% at 3 years for tumors without risk factors and 60% at 1 year and 40% at 2 years for tumors with at least one risk factor. Among the 50 repeat RF ablation sessions, pneumothorax occurred in 13 sessions (26%), one of which necessitated chest tube placement; pleural effusion occurred in nine sessions (18%), all of which resolved spontaneously. Thermal injury of the brachial plexus occurred after one session. CONCLUSIONS: Repeat RF ablation improved the overall local control outcomes. In particular, it offered an opportunity to salvage tumors that had no risk factors but nevertheless progressed locally after the first RF ablation. Conversely, tumors with risk factors were not controlled sufficiently even after repeating the procedure.     

Simultaneous Stereotactic Radiofrequency Ablation of Multiple (≥ 4) Liver Tumors: Feasibility,Safety, and Efficacy

PurposeTo assess feasibility, safety, and clinical outcome of simultaneous stereotactic radiofrequency (RF) ablation of multiple (≥ 4) primary and metastatic liver tumors.Materials and MethodsThis retrospective observational study included 92 patients (29 women, 62 men), 35 with ≥ 4 hepatocellular carcinomas (HCCs) and 57 with ≥ 4 metastatic liver tumors at initial stereotactic RF ablation between 2005 and 2018. The median size of 178 HCCs and 371 metastases was 2.2 cm (range, 1.0–8.5 cm) and 3.0 cm (range, 0.5–13 cm), respectively. At initial stereotactic RF ablation, 17 (48.6%) patients with HCC and 19 (33.3%) with metastases had 4 liver tumors, 11 (31.4%) and 19 (33.3%) had 5 tumors, and 7 (20%) and 19 (33.3%) had ≥ 6 tumors.ResultsMajor complications occurred in 2 of 35 ablations (5.4%) in patients with HCCs and in 7 of 63 (10%) with metastases. The primary technical efficacy rate (ie, successful initial ablation) was 100% (178/178) in HCCs and 98.8% (363/371) in metastases. Local recurrence was observed in 4 of 178 (2.2%) HCCs and in 17 of 371 (4.6%) metastases. Overall survival (OS) rates at 1, 3, and 5 years from the date of the first stereotactic RF ablation were 88.0%, 54.0%, and 30.4% for patients with HCCs with a median OS of 38.2 months and 86.1%, 53.1%, and 37.3% for patients with metastases with a median OS of 37.4 months.ConclusionsStereotactic RF ablation is a feasible, safe, and efficacious option in simultaneous management of multiple primary and metastatic liver tumors.     

Small hepatocellular carcinoma: comparison of radio-frequency ablation and percutaneous microwave coagulation therapy

PURPOSE: To evaluate the effectiveness of radio-frequency (RF) ablation and percutaneous microwave coagulation (PMC) for treatment of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Seventy-two patients with 94 HCC nodules were randomly assigned to RF ablation and PMC groups. Thirty-six patients with 48 nodules were treated with RF ablation, and 36 patients with 46 nodules were treated with PMC. Therapeutic effect, residual foci of untreated disease, and complications of RF ablation and PMC were prospectively evaluated with statistical analyses. RESULTS: The number of treatment sessions per nodule was significantly lower in the RF ablation group than in the PMC group (1.1 vs 2.4; P <.001). Complete therapeutic effect was achieved in 46 (96%) of 48 nodules treated with RF ablation and in 41 (89%) of 46 nodules treated with PMC (P =.26). Major complications occurred in one patient treated with RF ablation and in four patients treated with PMC (P =.36). During follow-up (range, 6-27 months), residual foci of untreated disease were seen in four of 48 nodules treated with RF ablation and in eight of 46 nodules treated with PMC. No significant difference in rates of residual foci of untreated disease was noted (P =.20, log-rank test). CONCLUSION: RF ablation and PMC thus far have had equivalent therapeutic effects, complication rates, and rates of residual foci of untreated disease. However, RF tumor ablation can be achieved with fewer sessions.     

Radiofrequency ablation for lung tumors: outcomes,effects on survival,and prognostic factors

PURPOSE

We aimed to evaluate the survival benefit achieved with radiofrequency (RF) ablation of primary and metastatic lung tumors and determine significant prognostic factors for recurrence-free survival.

METHODS

Forty-nine patients with lung cancer (10 primary and 39 metastatic) underwent computed tomography-guided percutaneous RF ablation between June 2005 and October 2013. A total of 112 tumors (101 metastatic and 11 primary non-small cell lung cancer) were treated with RF ablation. Tumor diameter ranged from 0.6 to 4 cm (median 1.5 cm). Effectiveness of treatment, complications, and survival were analyzed.

RESULTS

Primary success rate was 79.5% and local tumor progression occurred in 23 tumors. Among tumors showing progression, 10 were re-treated with RF ablation and secondary success rate was 87.5%. One-, two-, and three-year overall survival rates of 10 patients with primary lung cancer were 100%, 86%, and 43%, respectively. One-, two-, three-, four-, and five-year overall survival rates for 39 patients with metastatic lung tumors were 90%, 73%, 59%, 55%, and 38%, respectively. One-, two-, three-, and four-year overall survival rates for 16 patients with colorectal pulmonary metastases were 94%, 80%, 68%, and 23%, respectively. Complications occurred in 30 sessions (24.6%). Pneumothorax occurred in 19 sessions with seven requiring image-guided percutaneous chest tube drainage. Tumor status (solitary or multiple) and presence of extrapulmonary metastasis at initial RF ablation were significant prognostic factors in terms of recurrence-free survival.

CONCLUSION

RF ablation is a safe and effective treatment with a survival benefit for selected patients with primary and secondary lung tumors.Primary lung cancer is the leading cause of cancer-related death worldwide (1). Treatment of primary lung cancers includes surgical resection, radiation therapy, chemotherapy, and thermal ablation. Surgical resection remains the treatment of choice for patients with early stage non-small cell lung cancer (NSCLC) (2). However, primary lung cancers are generally diagnosed in advanced stages. Moreover, due to the high incidence of associated comorbidities and limited pulmonary reserve, most patients are considered ineligible for surgery (3, 4).In addition to primary cancers, lungs are the second most frequent site of metastatic disease. In selected patients with metastatic lung cancer, surgical resection is the preferred treatment. However, even patients who have undergone a complete resection have a high incidence of recurrence and may require multiple surgeries (5). Repeat thoracotomy leads to further removal of functional pulmonary tissue. Surgical resection might not be possible in patients with certain comorbidities and limited pulmonary reserve.Patients with pulmonary colorectal metastases constitute a significant portion of metastatic lung tumor group. Approximately 10% of patients with colorectal cancer develop pulmonary metastases during the course of disease (6). It has been reported that in patients with limited colorectal pulmonary metastases and no extrapulmonary disease, five-year survival following surgical resection is approximately 35%–45% (7). However, many patients are not suitable candidates for surgery.Percutaneous image-guided radiofrequency (RF) ablation is a minimally invasive technique established in the treatment of solid tumors. Since Dupuy et al. (8) reported the first clinical use of RF ablation to treat lung cancer in 2000, it has been increasingly used as a treatment option for patients with primary and secondary lung tumors, who are not surgical candidates. RF ablation offers reduced morbidity and mortality, and allows preservation of pulmonary functions because surrounding uninvolved lung parenchyma is preserved (9, 10). It is very useful for patients who have limited pulmonary reserve or with multifocal or bilateral metastatic disease. It is performed with computed tomography (CT) guidance and avoids thoracotomy in patients with significant comorbidities or in patients who refuse surgery. Repeatability of the procedure is a great advantage (11). It can be performed on an outpatient basis or with a minimum hospital stay (12).The aim of this study was to evaluate the survival benefit achieved with RF ablation for primary and secondary lung tumors and determine significant prognostic factors in terms of recurrence-free survival.     

Adrenal neoplasms: CT-guided radiofrequency ablation--preliminary results

PURPOSE: To evaluate initial experience with radiofrequency (RF) ablation of adrenal neoplasms. MATERIALS AND METHODS: Thirteen adrenal masses in 12 patients (bilateral metastases in one patient) were treated with computed tomography (CT)-guided percutaneous RF ablation. Eleven adrenal lesions were metastases (five from lung cancer, four from renal cell carcinoma, and two from melanoma); one lesion was a pheochromocytoma and one was an aldosteronoma. There were 10 men and two women (average age, 58 years; range, 40-77 years) in the study; average adrenal mass diameter was 3.9 cm (range, 1-8 cm). Average number of RF applications per adrenal mass was 2.7 (range, 1-5 applications); average time per application was 7.8 minutes (range, 4-13 minutes). An internally cooled single electrode was used in five sessions; an internally cooled cluster electrode was used in eight sessions. RESULTS: Average follow-up was 11.2 months (range, 1-46 months). Eleven of 13 lesions were treated successfully with RF ablation after one session. Successful treatment was defined as lack of enhancement of the treated region on follow-up CT images and resolution of the biochemical abnormality in two patients. In two patients with large adrenal lesions (4 and 8 cm in diameter), enhancement of residual tissue was observed after one treatment session; this finding was indicative of residual tumor. One patient with thrombocytopenia that resulted from chemotherapy had a small hematoma, but no transfusion was required. No patient developed hypertension during the RF application. No patient with metastases had recurrent tumor at the treated site, and this lack of recurrence indicated effective local control; 11 patients had progression of metastatic disease at extraadrenal sites. CONCLUSION: Preliminary data suggest that CT-guided RF ablation is an effective technique for local control of adrenal neoplasms.     

Osteoid osteoma: CT-guided percutaneous radiofrequency ablation and follow-up in 47 patients

PURPOSE: To evaluate computed tomography (CT)-guided radiofrequency (RF) ablation as a minimally invasive therapy for osteoid osteoma with regard to technical and clinical success and immediate and delayed complications. MATERIALS AND METHODS: Forty-seven patients (age range, 8-41 y; mean age, 19.6 y) with osteoid osteomas (femur, n = 25; tibia, n = 15; pelvis, n = 2; humerus, n = 1; ulna, n = 1; talus, n = 1; calcaneus, n = 1; vertebral body, n = 1) were treated with CT-guided RF ablation in 15 cases after one (n = 10) or two (n = 5) unsuccessful attempts at open surgical resection. Percutaneous therapy was performed with use of general or spinal anesthesia. After localization of the nidus with 1-3-mm CT sections, osseous access was established with either a 2-mm coaxial drill system or an 11-gauge Jamshidi needle. RF ablation was performed at 90 degrees C for a period of 4-5 minutes with use of a rigid RF electrode with a diameter of 1 mm. The procedures were regarded as technically successful if the tip of the RF electrode could be placed within the center of the nidus and could be heated to the desired temperature. Clinical success of treatment was defined as permanent relief of pain and return to normal function without additional treatment. In case of persistence or recurrence of symptoms after RF ablation, treatment was regarded as secondarily successful if permanent relief of symptoms could be achieved in a second procedure. RESULTS: All procedures were technically successful. Clinical success was achieved in 94% of patients (44 of 47). Three patients had recurrence of pain 3, 5, and 7 months after treatment, respectively (mean observation interval, 22 mo). All recurrences were treated successfully in a second procedure (secondary success rate, 100%). No immediate or delayed complications were observed. CONCLUSION: CT-guided percutaneous RF ablation is a simple, minimally invasive, safe and highly effective technique for treatment of osteoid osteoma.