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.     

Transthoracic percutaneous radiofrequency ablation for liver tumors in the hepatic dome

Computed tomography (CT)-guided transthoracic radiofrequency ablation was performed for nine liver tumors of eight patients, which were located in the hepatic dome and undetectable by ultrasound (US). A total 11 sessions of ablation were performed. Complications were noted in five sessions (45%) and no complications were noted in six sessions (55%). Pneumothorax was noted in five sessions (45%), including two sessions (18%) with major pneumothorax requiring a chest tube. Major complications were seen in two sessions (18%), major pneumothorax and both major pneumothorax and moderate pleural effusion, respectively. CT-guided transthoracic radiofrequency ablation may be an alternative for treatments of liver tumor in the hepatic dome.     

Image-Guided Percutaneous Radiofrequency Ablation of Central Renal Cell Carcinoma: Assessment of Clinical Efficacy and Safety in 31 Tumors

Purpose

To assess clinical efficacy and safety of image-guided percutaneous radiofrequency (RF) ablation of central renal cell carcinoma with adjunctive pyeloperfusion.

Intrahepatic tumor recurrence after partial hepatectomy: value of percutaneous radiofrequency ablation

PURPOSE: To determine the risks and benefits of percutaneous radiofrequency (RF) ablation of recurrent hepatic tumors in patients who have undergone hepatic resection. MATERIALS AND METHODS: Retrospective review of the institutional RF ablation database yielded 35 patients with recurrent hepatic tumor after hepatectomy. Sixty-one recurrent hepatic tumors (mean diameter +/- SD, 1.7 +/- 1.1 cm; range, 0.5-5.3 cm) were ablated percutaneously under sonographic guidance or combined guidance with sonographic and fluoroscopic computed tomography (CT). Follow-up CT, magnetic resonance imaging, or both were used for assessment of the primary and secondary therapeutic effectiveness rate and failure of RF ablation. Patients' survival status was determined by contacting the primary care physician or searching the Social Security Death Index. RESULTS: Complete ablation was accomplished in 54 of 61 hepatic tumors (primary therapeutic effectiveness rate, 88.5%). During a mean follow-up time of 18 months (range, 1-65 months), 14.8% of the tumors (n = 9) were incompletely ablated. Three of the nine incompletely ablated tumors were treated with a second RF ablation, all three of which failed (secondary therapeutic effectiveness rate, 0%). Distant intrahepatic tumor progression appeared in 23 of 35 patients (65.7%). One major complication (2.1%, one of 48 sessions) and eight minor complications (16.7%, eight of 48 sessions) were reported. The major complication was hepatic abscess formation. The overall survival rates for all patients at 1, 2, and 3 years were 76%, 68%, and 45%, respectively. For patients with metastases from colorectal cancer (n = 14), the overall survival rates were 72%, 60%, and 60% at 1, 2, and 3 years, respectively; and for patients with hepatocellular carcinoma (n = 8), the overall survival rates were 72%, 58%, and 44% at 1, 2, and 3 years, respectively. CONCLUSION: Percutaneous RF ablation offers a safe and effective treatment option for recurrent hepatic tumors after previous partial hepatectomy.     

Unresectable pulmonary malignancies: CT-guided percutaneous radiofrequency ablation--preliminary results

PURPOSE: To assess whether percutaneous radiofrequency (RF) ablation of unresectable pulmonary malignancies is safe and technically feasible and to evaluate the usefulness of computed tomographic (CT) nodule densitometry as a tool for following up tumors after ablation. MATERIALS AND METHODS: Twelve patients (seven men and five women; mean age, 60.6 years) with unresectable disease (because of poor lung reserve or multifocality) underwent nodule CT densitometry and CT-guided percutaneous RF ablation of 19 lung tumors (six [32%] tumors were adenocarcinoma, one (5%) was large cell carcinoma, two (10%) were bronchoalveolar carcinoma, four (21%) were colorectal carcinoma, and six (32%) were sarcoma less than 50 cm2 in area (range, 0.25-35.00 cm2). No patients had symptoms of their disease before RF ablation. Follow-up CT densitometry was scheduled for 1, 3, 6, and 12 months after RF ablation. Lesions were evaluated for change in area and contrast enhancement at follow-up CT. RESULTS: RF ablation was well tolerated by all patients. Intraprocedural complications included 12 cases of pneumothoraces (two patients required chest tube placement, while 10 were asymptomatic and required no further treatment), two cases of pleural effusion, and two cases of moderate pain (one case during and one case both during and after the procedure). Mean follow-up was 4(1/2) months (range, 1-12 months). In the eight patients with 3-month follow-up, lesion size increased in two and remained stable in six. Mean contrast enhancement, however, decreased from 46.8 HU (range, 19-107 HU) at baseline to 9.6 HU (range, 0-32 HU) at 1-2-month follow-up. In the one patient with 12-month CT densitometry follow-up, lesion enhancement was less than 50% of that at baseline, and lesion diameter remained stable. CONCLUSION: These preliminary results show that percutaneous RF ablation is a safe and technically feasible management option for unresectable pulmonary malignancies. CT densitometry may have potential for future use as a noninvasive method of following up tumors after RF ablation.     

Risk factors for occurrence of local tumor progression after percutaneous radiofrequency ablation for lung neoplasms

PURPOSE: To examine the characteristics of lung tumors for which radiofrequency (RF) ablation therapy is effective, and to determine what RF ablation parameters are effective for obtaining complete coagulation of the entire ablation zone with a single RF ablation session. MATERIALS AND METHODS: Computed tomography (CT)-guided RF ablation of lung tumors was performed on 82 lesions in 34 patients between April 2003 and May 2005. Tumor characteristics and ablation parameters, including tumor size, location, and depth, and ablation duration, power deployed during ablation, and temperatures achieved were analyzed with regard to local tumor progression. RESULTS: In all, 103 RF ablation sessions were performed on 82 tumors. As a procedure-related complication, pneumothorax occurred in 27 procedures. During the mean follow-up period of 10 months (range, 6-28 months), local tumor progression occurred in 18 (22.0%) of the 82 ablated tumors (3 months after RF ablation in 10, 6 months after RF ablation in 5, 9 months after RF ablation in 1, and 12 months after RF ablation in 2). Mean local progression-free duration was 8.7 +/- 4.5 months (range, 3-28 months). The frequency of local tumor progression was significantly correlated with size, whereas other variables had no statistical association. In tumors with a diameter > or =2.5 cm, only the period of ablation during the initial session was significantly correlated with subsequent local tumor progression (P = 0.000002, chi-square test). CONCLUSION: A long duration of RF ablation is desirable for large lung tumors. The success of RF ablation is dependent upon tumor size. RF ablation treatment is most effective for lesions < 2.5 cm.     

Midterm local efficacy and survival after radiofrequency ablation of lung tumors with minimum follow-up of 1 year: prospective evaluation

PURPOSE: To prospectively evaluate the local efficacy of radiofrequency (RF) ablation of lung neoplasms, with a minimum follow-up period of 1 year. MATERIALS AND METHODS: Sixty patients (34 men and 26 women; age range, 27-81 years; mean age, 66 years) with 100 lung tumors gave written informed consent to be enrolled in a prospective study that was approved by the local ethics committee. There were five or fewer tumors per patient, each with a diameter of less than 40 mm (mean +/- standard deviation, 17 mm +/- 10). RF ablation was performed in tumors by using computed tomographic (CT) guidance. Follow-up CT studies were obtained within 48 hours after treatment and at 2, 4, 6, 9, and 12 months thereafter to evaluate treatment outcome and complications. Lung spirometry measurements were obtained before and 4 weeks after RF ablation. RESULTS: Ninety-seven of 100 targeted tumors were treated and required 163 RF ablations (1.68 per tumor), each lasting 14 minutes +/- 8, delivered during 74 procedures. The 18-month estimated rate of incomplete local treatment at CT was 7% (95% confidence interval: 3%, 14%) per tumor and 12% (95% confidence interval: 5%, 23%) per patient. An ablation area at least four times larger than the initial tumor was predictive of complete ablation treatment (P = .02). There was a trend toward better efficacy for tumors smaller than 2 cm in diameter (P = .066). Overall survival and lung disease-free survival at 18 months were 71% and 34%, respectively. The main adverse event was a pneumothorax, which occurred in 54% of procedures, but a chest tube was required in only 9% of the procedures. No modification of respiratory function was found when spirometry measurements obtained before and within 2 months after RF ablation were compared (P = .51). CONCLUSION: RF ablation has a high local efficacy and is well tolerated.     

Percutaneous radiofrequency ablation for pulmonary metastases from colorectal cancer: midterm results in 27 patients

PURPOSE: To retrospectively evaluate the midterm outcomes (eg, safety, local efficacy, and survival) after radiofrequency (RF) ablation for pulmonary metastases from colorectal cancer. MATERIALS AND METHODS: Twenty-seven patients (19 men and eight women; mean age, 61.6 years) with 49 pulmonary metastases (mean long axis diameter, 1.5 cm) from colorectal cancer underwent 41 percutaneous computed tomography (CT)-guided RF ablation sessions. Follow-up examinations were performed with CT by using contrast medium administration in all patients; positron emission tomography was performed in five patients. The safety of the procedure, local tumor control, and patient survival were evaluated. Multiple variables were analyzed to determine prognostic factors. RESULTS: Pneumothorax occurred after 20 of the 41 sessions (49%), three of which necessitated chest tube placement. A small pleural effusion was found after six of the 41 sessions (15%). No major hemorrhagic event was observed. None of the patients died due to the procedure. The median follow-up period was 20.1 months (range, 11.2-47.7 months). The primary and secondary technique effectiveness rates were 72% and 85%, respectively, at 1 year, 56% and 62% at 2 years, and 56% and 62% at 3 years. The overall survival rates after RF ablation were 96% at 1 year, 54% at 2 years, and 48% at 3 years. The presence of extrapulmonary metastasis was determined to be a prognostic factor (P = .001). CONCLUSIONS: The midterm outcomes of percutaneous RF ablation for colorectal pulmonary metastases appear promising. The presence of extrapulmonary metastasis had an adverse effect on survival after RF ablation.     

Radiofrequency ablation for the treatment of liver tumors in the caudate lobe

PURPOSE: To evaluate the effectiveness of radiofrequency (RF) ablation for liver tumors located in the caudate lobe. MATERIALS AND METHODS: Ten patients (46-79 years of age; median, 70 y), eight with hepatocellular carcinoma (HCC) and cirrhosis and two with colorectal metastases in the caudate lobe, were treated with 5.8% NaCl tissue-perfused monopolar (n=7) or bipolar (n=3) RF ablation. The median tumor diameter was 41 mm (range, 25-70 mm). Procedures were performed under ultrasound and computed tomography (CT) guidance in eight and two patients, respectively. One month later, the treatment response was assessed by CT. RESULTS: Transhepatic right intercostal and transomental anterior epigastric routes were used for tumor puncture in eight and two patients, respectively. The entire RF ablation treatment required one or two procedures (median, 1.5), including two to 15 electrode repositionings (median, 6). After RF ablation procedure, one patient experienced jaundice that resolved spontaneously. In one patient, CT follow-up showed asymptomatic segmental biliary duct dilations. Median total hospital stay was 3 days (range, 2-9 d). Complete ablation was achieved in nine of 10 tumors. In one patient, ethanol ablation was necessary to complete RF ablation treatment. After a median follow up of 9.5 months (range, 5-25 mo), three patients remained tumor-free and seven had tumor relapse: two local, four distant, and one mixed. Repeat RF ablation was successfully performed in four cases. CONCLUSION: RF ablation of liver tumors located in the caudate lobe is effective despite the deep location of tumors and the vicinity of major vessels.     

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.     

Immediate renal tumor involution after radiofrequency thermal ablation

PURPOSE: To retrospectively evaluate solid renal tumor sizes before and after treatment with radiofrequency (RF) thermal ablation to assess for immediate changes on cross-sectional imaging. MATERIALS AND METHODS: Medical records were retrospectively reviewed in consecutive patients who underwent percutaneous image-guided RF thermal ablation for solid renal tumors between December 12, 2000, and December 13, 2006. All patients underwent noncontrast computed tomography (CT) immediately before and after RF ablation. Maximum renal tumor diameters were measured before and after ablation. Statistical analysis of tumor sizes before and after ablation and change in tumor sizes was performed with the paired Student t test with confidence intervals calculated. RESULTS: Seventy-two renal tumors were treated with RF ablation in 66 patients (42 men, 24 women; mean age, 68.4 years; range, 25-88 y). Mean tumor sizes were 27.5 mm (range, 9.8-64.8 mm; 95% CI, 24.9-30.1 mm) before ablation and 22.1 mm (range, 5.3-67.3 mm; 95% CI, 19.4-24.8 mm) immediately after ablation. An average decrease in renal tumor size of 21% (range, -10% to 50%) was identified, with a mean tumor diameter decrease of 5.4 mm (P < .05; 95% CI, 4.4-6.4 mm). No relationship between size or location of tumors and percentage decrease in size after RF ablation was identified. Measurement of tumors on 1-month follow-up CT showed no appreciable change compared with immediate postprocedural measurements. CONCLUSIONS: Renal tumors decrease in size immediately after treatment with RF thermal ablation. Immediate tumor involution after RF ablation should be anticipated and follow-up imaging studies should ideally be compared to a baseline tumor size measured as soon as possible after ablation.     

肝癌电磁波热凝治疗消融术后的CT表现分析

目的:分析肝癌电磁波热凝治疗(微波固化或射频消融)后的常见和特殊CT表现,提高对电磁波热凝治疗消融后肝脏形态改变和局部并发症的认识。方法:26例消融治疗后的肝癌患者,术后2周行CT扫描,3个月内复查CT,结合临床症状和实验室检查指标,分析射频消融治疗后肝脏形态的一般变化和出现局部并发症时的特殊征象。结果:电磁波热凝治疗消融后18例病灶呈术后正常改变,CT平扫为边界清楚、均质的低密度区,增强扫描无强化,而坏死区周边可见薄的环形强化,病灶范围较治疗前稍大,随治疗后的时间延长坏死区周边的环形强化逐渐减弱至消失,而中心坏死区仍为低密度,无强化,病灶较前逐渐缩小。消融后复发4例,CT表现为消融治疗区域周边的新发低密度灶。胆道损伤2例,CT表现为消融治疗区域周边肝内胆管扩张。肝内假性囊肿形成1例,CT示消融治疗区旁边缘锐利无强化的囊性灶;皮肤瘘道形成并胸腔积液1例,CT表现为消融治疗的针道不愈合,肝脏内病灶坏死区与体表相连通。结论:CT可准确地反映原发性肝癌电磁波热凝治疗消融后肝脏的形态学改变,有效观察局部并发症的发生情况,有助于提高对电磁波热凝治疗术后征象的认识。     

Percutaneous biopsy of thoracic lesions: value of sonography for needle guidance

Fluoroscopy and CT are widely used to guide percutaneous needle biopsy of thoracic lesions. However, some lesions are not sufficiently visible on fluoroscopy and others are dangerous to access on CT without real-time monitoring. When these are the circumstances, sonographic guidance may be helpful. Real-time sonography was used to guide percutaneous needle biopsy in 124 patients with thoracic lesions. The indications for sonographic guidance included pulmonary, pleural, or mediastinal lesions in contact with the chest wall, including lesions near the heart or great vessels (n = 12); lesions in the apical region (n = 5); lesions in a juxtadiaphragmatic location (n = 6); small lung nodules adjacent to the chest wall (n = 16); and peripheral tumors with adjacent pleural effusion (n = 4). A diagnosis was made in 74 (90%) of 82 malignant lesions and in 24 (67%) of 36 benign lesions. Complications included pneumothorax (n = 5), hemoptysis (n = 1), and hemothorax (n = 1). The advantages of sonographic guidance are that the sonographic equipment is mobile and real-time monitoring makes the procedure safer. Its limitations are that it cannot be used when aerated lung or free air (pneumothorax) lies between the chest wall and the lesion and that cavitary lesions are difficult to sample by biopsy. Our results show that the use of sonographic guidance considerably expands the number of thoracic lesions amenable to percutaneous biopsy.     

Small hepatocellular carcinoma: treatment with radio-frequency ablation versus ethanol injection

PURPOSE: To compare the effectiveness of radio-frequency (RF) ablation with that of percutaneous ethanol injection in the treatment of small hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Eighty-six patients with 112 small (< or = 3-cm-diameter) HCCs underwent RF ablation (42 patients with 52 tumors) or percutaneous ethanol injection (44 patients with 60 tumors). Therapeutic efficacy was evaluated with dual-phase spiral computed tomography performed at least 4 months after treatment. RESULTS: Complete necrosis was achieved in 47 of 52 tumors with RF ablation (90%) and in 48 of 60 tumors with percutaneous ethanol injection (80%). These results were obtained with an average of 1.2 sessions per tumor with RF ablation and 4.8 sessions per tumor with percutaneous ethanol injection. One major complication (hemothorax that required drainage) and four minor complications (intraperitoneal bleeding, hemobilia, pleural effusion, cholecystitis) occurred in patients treated with RF ablation; no complications occurred in patients treated with percutaneous ethanol injection. CONCLUSION: RF ablation results in a higher rate of complete necrosis and requires fewer treatment sessions than percutaneous ethanol injection. However, the complication rate is higher with RF ablation than with percutaneous ethanol injection. RF ablation is the treatment of choice for most patients with HCC.     

Vacuum-assisted resection of malignant tumors with and without subsequent radiofrequency ablation: feasibility of complete tumor treatment tested in an animal model

PURPOSE: To evaluate the feasibility of vacuum-assisted tumor excision with and without RF ablation for the minimally invasive treatment of small tumors. MATERIALS AND METHODS: Twenty VX2 tumors were implanted bilaterally into the spine muscle of 10 rabbits. Tumor excision was performed after tumor sizes reached 10 mm (12-27 d incubation) with use of a vacuum-assisted biopsy device. Three or four directed vacuum-assisted biopsies were performed in angle steps of 30 degrees. In 10 tumors, ultrasound (US)-guided radiofrequency (RF) ablation (8 min, 60 W) was subsequently performed with use of a cooled-tip electrode system. Follow-up US was performed at 3-4-day intervals for as long as 3 weeks after excision/RF ablation. Autopsy and histopathologic analysis were performed. RESULTS: The duration of vacuum excision ranged from 12 to 45 minutes (25 min +/- 7). Histologically tumor-free margins in the outer round of the core biopsy specimens were found in only four of 20 cases (20%). Maximum lesion sizes during RF ablation ranged from 18 to 25 mm (20 mm +/- 2.6). Histologic examination of the excision specimens documented tumor-free margins in only three tumors (30%) among the excision-only group and only one (10%) among the combined excision/ablation group. Local recurrences occurred in eight of 10 cases (80%) after vacuum excision alone, whereas recurrence after combined excision and RF ablation occurred only in two of 10 cases (20%; P <.05). CONCLUSIONS: Local tumor resection with use of vacuum-assisted biopsy is feasible and promising as a minimally invasive therapy for the treatment of small focal breast neoplasms. Combined excision and RF ablation techniques may reduce the rate of local recurrence considerably.     

Protecting the ureter during radiofrequency ablation of renal cell cancer: a pilot study of retrograde pyeloperfusion with cooled dextrose 5% in water

PURPOSE: To describe early experience with cooled dextrose 5% in water (D5W) solution retrograde pyeloperfusion during radiofrequency (RF) ablation of renal cell carcinoma (RCC) within 1.5 cm of the ureter with respect to feasibility, safety, and incidence of residual/recurrent tumor in proximity to the cooled collecting system. MATERIALS AND METHODS: Between November 2004 and April 2007, 17 patients underwent 19 RF ablation sessions of RCCs within 1.5 cm of the ureter during cooled D5W pyeloperfusion (nine men, eight women; mean tumor size, 3.5 cm; mean age, 73 y; mean distance to ureter, 7 mm). RF ablation was performed with pulsed impedance control current. The records and imaging studies of patients treated with this technique were reviewed for demographics, indication, technique, complications, and tumor recurrence. RESULTS: All 19 RF ablation and ureteral catheter placement procedures were technically successful. No patient developed a ureteral stricture or hydronephrosis during a mean of 14 months of follow-up (range, 4-32 months). Three patients had residual tumor on the first follow-up imaging study, but all three tumors were completely ablated after a second RF ablation session. No complications or deaths occurred. No recurrent tumor was seen anywhere in the treated tumors, and there was complete ablation of the tumor margin in proximity to the collecting system. CONCLUSIONS: RF ablation of RCC within 1.5 cm of the ureter is feasible with cooled D5W retrograde pyeloperfusion and is not associated with reduced efficacy, ureteral injury, or early recurrence.     

Recurrent hepatocellular carcinoma: percutaneous radiofrequency ablation after hepatectomy

PURPOSE: To evaluate the therapeutic efficacy and safety of percutaneous radiofrequency (RF) ablation for recurrent hepatocellular carcinoma (HCC) in the liver after hepatectomy. MATERIALS AND METHODS: Forty-five patients with 53 recurrent HCC tumors in the liver underwent percutaneous RF ablation with ultrasonographic guidance. All patients had a history of hepatic resection for HCC. The mean diameter of recurrent tumors was 2.1 cm (range, 0.8-4.0 cm). All patients were followed up for at least 10 months after ablation (range, 10-40 months; mean, 23 months). Therapeutic efficacy and complications were evaluated with multiphase helical computed tomography (CT) at regular follow-up visits. Overall and disease-free survival rates were calculated. RESULTS: At follow-up CT after initial RF ablation, 11 (21%) of 53 ablated HCC tumor sites showed residual tumor or local tumor progression. After additional RF ablation, complete ablation of 46 (87%) of 53 tumors was attained. Also at initial follow-up CT, before either additional RF ablation or other treatment was performed, 21 (47%) of 45 patients were found to have 41 new HCC tumors at other liver sites. Of these, nine tumors in eight patients were treatable with a second application of RF ablation. Overall survival rates at 1, 2, and 3 years were 82%, 72%, and 54%, respectively. No deaths or complications requiring further treatment occurred as a result of RF ablation. CONCLUSION: Percutaneous RF ablation is an effective and safe method for treating recurrent HCC in the liver after hepatectomy, with a good overall patient survival rate.     

Percutaneous radiofrequency ablation for unresectable large hepatic tumours during hepatic blood flow occlusion in four patients

AIM: To evaluate percutaneous radiofrequency (RF) ablation therapy for unresectable large hepatic tumours combined with regional interruption of hepatic blood flow, and to assess the safety and efficacy of this procedure. MATERIALS AND METHODS: Four patients with hepatic tumours were enrolled in this study. Patients were treated by a single session of RF ablation during occlusion of both hepatic artery and hepatic vein. Tumour size ranged from 45-57 mm (mean 50.2 mm). Initial therapeutic efficacy was evaluated with helical computed tomography (CT) performed within 9 days after the treatment. CT or magnetic resonance imaging (MRI) was performed every 2-3 months thereafter. RESULTS: The largest axis of coagulated lesions after the ablation was 50-60 mm (mean 56.5 mm) in diameter. The ablation therapy was considered complete in three patients; after a mean follow-up of 12.7 months, CT and MRI revealed complete destruction of their tumours. One patient required further treatment. No severe complications occurred. CONCLUSION: Although further studies are needed, in this limited clinical trial a local ablation area exceeding 50 mm in diameter was achieved safely.     

Radiofrequency ablation: effect of surrounding tissue composition on coagulation necrosis in a canine tumor model

PURPOSE: To determine the effect of surrounding tissue type on coagulation necrosis from radiofrequency (RF) ablation in a homogeneous animal tumor model. MATERIALS AND METHODS: Thirty canine venereal sarcomas were implanted in three tissue sites (subcutaneous, kidney, and lung) in 13 mildly immunosuppressed dogs. Five of 25 tumors, which were 19 mm +/- 3 (mean +/- SD) in diameter, were allocated to each of five groups: (a) subcutaneous tumors, (b) kidney tumors, (c) lung tumors with blood flow, and (d) subcutaneous and (e) renal tumors without blood flow, which was achieved by sacrificing the animal to eliminate tumor perfusion. A sixth group comprised larger subcutaneous tumors (mean diameter, 46 mm +/- 4) that were also treated. RF ablation was performed with a 1-cm tip and 5 minutes of ablation at 90 degrees C +/- 1. Impedance, temperature, and resultant coagulation diameter were recorded and compared. Data were analyzed statistically, including one-way analysis of variance to determine the effect of tissue conductivity (ie, systemic impedance) on necrosis size and tissue temperatures. Linear regression analysis was used to compare changes in impedance between the control and experimental groups. RESULTS: Increasing linear correlation was observed between tumor coagulation diameter and overall baseline system impedance (R(2) = 0.65). RF ablation of lung tumors resulted in the greatest coagulation diameter (13.0 mm +/- 3.5) compared with that in the other groups (P <.01). The smallest coagulation diameter was observed in kidney tumors in the presence of blood flow (7.3 mm +/- 0.6) compared with that in the other groups (P <.01). Elimination of blood flow in kidney tumors increased coagulation diameter to 10.3 mm +/- 0.6 (P <.01). After RF ablation, coagulation diameter in the subcutaneous tumor groups was the same (mean, 9.8 mm +/- 1.0) (difference not significant), regardless of tumor size or presence of blood flow. CONCLUSION: The characteristics of tissue that surrounds tumor, including vascularity and electric conductivity, affect ablation outcome. Predominance of tissue-specific characteristics will likely result in site-specific differences in RF-induced coagulation necrosis.     

Radiofrequency Ablation Combined with Renal Arterial Embolization for the Treatment of Unresectable Renal Cell Carcinoma Larger Than 3.5 cm: Initial Experience

The purpose of the study was to evaluate the feasibility, safety, and therapeutic effects of the combination of renal arterial embolization and radiofrequency (RF) ablation to reinforce the anticancer effect on renal cell carcinomas (RCCs) measuring 3.5 cm or larger. This study was undertaken to evaluate this combined therapy on large RCCs-based tumor geometry. Eleven patients with 12 RCCs 3.5 cm or larger in diameter (3.5–9.0 cm) underwent combined therapy. Two were exophytic tumors, and the remaining 10 tumors had components extending into the renal sinus fat. Tumor vessels were selectively embolized in nine patients and the renal artery was completely embolized in two patients with polyvinyl alcohol or ethanol mixed with iodized oil. RF ablation was percutaneously done under the computed tomographic (CT)–fluoroscopic guidance. Response to treatment was evaluated by dynamic contrast-enhanced CT and magnetic resonance (MR) imaging. Tumor enhancement was eliminated after a single RF session in nine tumors (75%), after two sessions in two tumors (17%), and after four sessions in one tumor (8%). Both exophytic tumors (100%) and 7 of 10 tumors having components in the renal sinus fat (70%) were completely ablated with a single RF session. All tumors remained controlled during a mean follow-up period of 13 months and showed significant reduction in tumor sizes (5.2 ± 1.7 cm to 3.6 ± 1.4 cm, p < 0.001). A delayed abscess developed in the ablated lesion in a patient, which was percutaneously drainaged. Combined therapy as described in this report is a feasible, relatively safe, and promising treatment method for large RCCs regardless of tumor geometry.