Multiple-electrode Switching System Research Articles

Risk factors for the recurrence of early hepatocellular carcinoma treated by percutaneous radiofrequency ablation with a multiple-electrode switching system: a multicenter prospective study

Purpose To investigate the long-term efficacy of radiofrequency ablation (RFA) with a multiple-electrode switching system (MESS) in the treatment of early hepatocellular carcinoma (HCC) and evaluate the patterns and risk factors of intrahepatic recurrence of HCC after RFA. Methods In total, 139 patients with early HCC who underwent RFA with MESS as primary treatment at multiple centers were prospectively enrolled according to the inclusion criteria. We evaluated the local tumor progression (LTP), intrahepatic distant recurrence (IDR), the incidence of cumulative disease-free survival (DFS), LTP-free survival, IDR-free survival, and overall survival. We also analyzed the associated risk factors. Results A total of 139 patients were included in the study and the median follow-up time was 64 months, ranging from 11 to 72 months. The complete ablation rate was 98.56%. Sixty-nine (49.64%) were found to have intrahepatic recurrence (LTP, n = 15; IDR, n = 55) during follow-up. The 1-year, 3-year and 5-year cumulative DFS, LTP-free survival, and IDR-free survival rates were 74.82, 94.46 and 78.75%; 54.68, 88.03 and 61.79%; and 51.80, 85.67 and 60.17%, respectively. In the multivariable analysis, tumor size > 4 cm was the only important risk factor for LTP. The alkaline phosphatase (ALP) level and the number of tumors were independent risk factors for IDR; α-fetoprotein (AFP) level > 400 µg/L and recurrence interval were risk factors for the overall survival period. Conclusions The MESS-RFA is an effective method for local control of tumors in early HCC. Early HCC with multiple high-ALP tumors has a higher rate of recurrence, which mainly occurs in an IDR pattern. Early HCC with high AFP levels and a shorter initial recurrence interval resulted in a poorer prognosis. Thus, treatments such as liver transplantation or surgical resection may be a good strategy in those cases. ClinicalTrials.gov ID NCT02046356.

Percutaneous Radiofrequency Ablation With a Multiple-Electrode Switching System for Medium-Sized Hepatocellular Carcinomas

Objective This study aimed to retrospectively evaluate the safety and short-term therapeutic efficacy of radiofrequency ablation (RFA) with a multiple-electrode switching system (MESS) to treat medium-sized (3.1–5.0 cm) hepatocellular carcinomas (HCCs). Summary of Background Data Conventional monopolar RFA is limited in achieving local control for tumors larger than 3 cm. Therefore, MESS-RFA was developed, and it can create a sufficiently large ablation volume, including the target tumor and a 5- to 10-mm safety margin in medium-sized tumors. Methods We performed a total of 168 RFAs with a MESS for 166 patients. The patients were treated under ultrasonographic guidance by a percutaneous switching system RFA with a multichannel RF generator and 2 or 3 internally cooled electrodes. Technical effectiveness, local progression, and remote recurrence of HCC were determined. Results For the 166 isolated HCC tumors, the complete ablation rate of MESS-RFA was 98.79% (164 of 166). Mean ablation time per procedure was 12.33 ± 3.01 minutes; mean ablation diameter was 5.79 ± 0.61 cm. The complication rate was 2.41%. During follow-up (averaging 16.54 months), local tumor progression occurred in 15 of 166 patients (9.03%) with technical effectiveness, whereas new HCCs were detected in 40 of 166 patients (24.09%). Multivariate analyses revealed that local tumor progression was only associated with serum α-fetoprotein levels above 100 ng/mL as a risk factor. Conclusion MESS-RFA for achieving sufficient ablation volume is safe and efficient. This method also showed relatively successful therapeutic effectiveness on short-term follow-up in the treatment of medium-sized HCCs.

Radiofrequency ablation using a multiple-electrode switching system for hepatocellular carcinoma within the Milan criteria: long-term results

Purpose: To assess the long-term outcome of 516 consecutive patients treated with multiple-electrode switching system (MESS) radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) that met the Milan criteria.Materials and methods: We performed 522 MESS RFAs on 516 patients from December 2006 to June 2011. A total of 956 tumours that met the Milan criteria with an average diameter of 2.64 cm (range, 0.9–4.6 cm) were treated with MESS RFA. Ultrasonic contrast and serum α-fetoprotein (AFP) were measured every 2 months during the first postoperative year and every 4 months thereafter. Enhanced computed tomography was performed every 6 months. Survival was estimated using the Kaplan–Meier method. Follow-up was censored at 60 months. Multivariate analysis was performed using the Cox proportional hazards model.Results: For the 956 HCC tumours, the complete ablation rate with MESS was 98.83% (510/516). During a median of 34 months (IQR, 23–52 months) of follow-up, 171 patients died and 4 were lost to follow-up (15, 30, 38 and 42 months). The cumulative incidence of local tumour progression at 1, 3 and 5 years was 0.39%, 4.96% and 6.66%, respectively, and the 1-, 3- and 5-year overall survival was 99.42%, 83.97% and 68.42%, respectively. Tumour size >30 mm was the only parameter that was predictive of local tumour progression (p < .0001). Risk factors associated with overall survival included prothrombin time >14 s, serum AFP levels >200 ng/mL and tumour abutting vessel diameter <5 mm. The complication rate was 1.74%.Conclusion: MESS RFA is a safe and effective method for HCC treatment. This approach results in a high local progression-free survival for HCC tumours that meet the Milan criteria.

Monopolar Radiofrequency Ablation for Medium-sized Hepatocellular Carcinoma: Preliminary Experience with Single-Electrode Overlapping Ablation and Multiple-Electrode Switching System

BackgroundRadiofrequency ablation (RFA) has been regarded as an effective treatment for early and small hepatocellular carcinoma (HCC). In vivo porcine studies showed a multiple-electrode switching system could create larger necrotic areas than single-electrode or cluster-electrode ablations. Some recent studies demonstrated a multiple-electrode RFA system could achieve local control of medium-sized HCCs. This study aimed to evaluate the treatment results of monopolar RFA with either single-electrode overlapping ablations or a multiple-electrode switching system in treating medium-sized (3-5 cm) HCC. MethodsA total of 20 patients with medium-sized hepatocellular carcinomas were included in this study. Nine patients (6 males and 3 females) were treated with single- electrode monopolar RFA. Eleven patients (4 males and 7 females) were treated with multiple- electrode switching monopolar RFA. Twelve patients (60%) included in this study had multi- nodular HCCs at the time of treatment. The tumor size was slightly larger in the multiple- electrode group (4.6 ± 0.3 cm) compared to that in the single-electrode group (3.6 ± 0.6 cm). CT or MR imaging studies were performed at 1 month after RFA to evaluate treatment effectiveness. Thereafter, local tumor progression, treatment effectiveness and survival after RFA were evaluated. ResultsOverall, 18 of 20 patients (90%) showed satisfactory ablation of HCCs 1 month after their RFA procedures. Treatment effectiveness was achieved in 8 patients (88.9%) with single-electrode overlapping ablation and 10 (90.9%) patients with multiple-electrode switching system. The mean follow-up periods were 14.9 (range, 2-26) months in the single-electrode group, and 20.2 (range 4-41) months in the multiple-electrode group. Among the 18 patients who achieved primary tumor control, 2 patients (1 in the single-electrode group and 1 in the multiple-electrode group) had local progression noted during follow-up examinations. ConclusionsMedium-sized hepatocellular carcinoma can be effectively ablated with monopolar radiofrequency ablation by either single-electrode overlapping ablation or a multiple-electrode switching system. Regarding mid-term treatment responses, both RFA approaches can achieve similar treatment effectiveness, local tumor progression rate, and survival probabilities. Multiple-electrode switching RFA can treat larger medium-sized HCC with comparable mid-term efficacy as smaller medium-sized HCC treated with single-electrode overlapping RFA.

Safety and Clinical Outcomes of Percutaneous Radiofrequency Ablation for Intermediate and Large Bone Tumors Using a Multiple-Electrode Switching System: A Phase II Clinical Study

PurposeTo evaluate the safety and clinical outcomes of radiofrequency (RF) ablation using a multiple-electrode switching system in patients with bone tumors > 3 cm. Materials and MethodsThis prospective study enrolled 20 subjects (15 men, 5 women; mean age 70.0 y ± 7.4 [SD]; range, 60–80 y) with malignant unresectable bone tumors. The maximum mean tumor diameter was 5.5 cm ± 2.0 (range, 3.1–10.0 cm). Two to three RF electrodes were placed into each bone tumor. Real-time CT fluoroscopic guidance was used with a multiple-electrode switching system. The primary endpoint was safety, as evaluated by Common Terminology Criteria for Adverse Events, until 12 months after bone RF ablation. As secondary endpoints, pain relief was evaluated by visual analog scale (VAS) scores before and 1 week after RF ablation; tumor response, by contrast-enhanced magnetic resonance imaging studies until 4 weeks after bone RF ablation; and survival, by Kaplan-Meier method. ResultsNo adverse event was found in 19 of 20 patients (95%). Grade 2 fever occurred in 1 patient (5%; 1/20). VAS scores decreased by ≥ 2 in 11 of 13 patients (84.6%) who had painful bone tumors. Tumor response (complete or partial response) was achieved in 16 of 18 patients (88.9%) who underwent follow-up imaging studies. The 1-year overall survival rate was 60.9%, and the median survival time was 14.1 months. ConclusionsBone RF ablation using this system is safe and achieves local tumor control and pain relief in patients with large bone tumors.

Abstract No. 376 - Percutaneous radiofrequency ablation for large bone tumors using a multiple electrode switching system: a phase-II clinical study

Purpose To prospectively evaluate the safety and outcomes of radiofrequency (RF) ablation using multiple electrode switching system for large bone tumors. Materials and Methods This prospective phase-II study was approved by our institutional review board and a written informed consent was obtained from all patients who had unresectable bone tumors measuring 3.1cm to 10cm. Two to 3 RF electrodes were placed into each bone tumor under the real-time CT-fluoroscopic guidance and activated by using a multiple electrode switching system. The primary endpoint was safety that was evaluated by Common Terminology Criteria for Adverse Events (CTCAE). The secondary endpoints were feasibility, changes in visual analogue scale (VAS) score, tumor response, and survival. Results Twenty patients (15 males and 5 females) with a mean age of 70.0 ±7.4 years (range, 60-80 years) were enrolled. The mean maximum tumor diameter was 5.5±2.0 cm (range, 3.1-10cm). Procedures were completed with a planned protocol in all patients. A grade-3 adverse event (femoral bone necrosis requiring total hip arthroplasty) was found 5 months later in a patient (5%, 1/20). VAS scores fell by 2 or more in 11 of 13 patients (84.6%, 11/13) who had painful bone tumors. Tumor enhancement disappeared completely in 6 of 18 patients (CR, 33.3%, 6/18) who received follow-up contrast-enhanced MR or CT images and more than 50% in 10 patients (PR, 55.6%, 10/18), ending up the response rate of 88.9% (16/18). The 1-year overall survival rate was 61.3%. Conclusion Bone RF ablation using multiple electrode switching system is a relatively safe, feasible, and effective in controlling tumor and relieving pain, which may lead to prolonging patient survival.

Small- and Medium-sized Hepatocellular Carcinomas: Monopolar Radiofrequency Ablation with a Multiple-Electrode Switching System—Mid-term Results

To prospectively assess the safety and mid-term therapeutic effectiveness of monopolar radiofrequency (RF) ablation with a multiple-electrode switching system for treating small- and medium-sized (≤ 5 cm) hepatocellular carcinomas (HCCs). The institutional review board approved this prospective study, and all patients gave informed consent. From February 2009 to January 2010, 166 patients (110 men and 56 women; age range, 38-86 years; mean age, 62 years ± 10 [standard deviation]) with 166 HCCs less than or equal to 5 cm in diameter were treated with monopolar RF ablation with a multiple-electrode switching system. One of three experienced radiologists performed the RF ablation. Technique effectiveness, ablation volume and time, and major complications were evaluated by means of computed tomography (CT) immediately after RF ablation and at follow-up CT examinations at 1 month and then every 3 months after the procedure. The overall survival, disease-free survival, and local tumor progression-free survival rates were evaluated by using the Kaplan-Meier method. The technique effectiveness rate determined 1 month after RF ablation was 99.4%. Mean ablation parameters were as follows: volume, 85 cm(3) ± 54; maximum diameter, 61 mm ± 13; and minimum diameter, 43 mm ± 11. The major complication rate was 4.8%. The 6-month and 1-, 2-, and 3-year local tumor progression rates were 2%, 6%, 10%, and 11%, respectively. The overall survival rates at 1, 2, and 3 years after RF ablation were 99%, 97%, and 96%, and corresponding local tumor progression-free survival rates were 94%, 90%, and 89%, respectively. The disease-free survival rates at 1, 2, and 3 years after RF ablation were 75%, 60%, and 54%, respectively. Monopolar RF ablation with a multiple-electrode switching system in small- and medium-sized HCCs was safe and efficient, and it provided successful local tumor control and high local tumor progression-free survival rates because an adequate ablation volume was obtained.

Renal Cell Carcinoma: Radiofrequency Ablation with a Multiple-Electrode Switching System—A Phase II Clinical Study

To prospectively evaluate the safety and effectiveness of radiofrequency ablation with a multiple-electrode switching system for the treatment of renal cell carcinoma (RCC). From November 2009 to December 2010, 33 patients (mean age, 70.7 years; range, 44-86 years) with histologically proved RCCs--including 24 men (mean age, 69.5 years [range, 44-86 years]) and nine women (mean age, 74.1 years [range, 64-83 years])--were enrolled in this phase II study. The institutional review board approved the study after patients provided written informed consent. The mean maximum tumor diameter was 2.9 cm ± 1.0 (standard deviation) (range, 1.5-5.0 cm). Radiofrequency ablation was conducted with a multiple-electrode switching system. The primary endpoint was evaluated with the Common Terminology Criteria for Adverse Events. Secondary endpoints were changes in renal function, technique effectiveness, local tumor progression, and survival. Changes in renal function were evaluated by using the Mann-Whitney U test. No severe adverse events occurred, but three of 33 patients (9%) had grade 2 adverse events. Although the mean glomerular filtration rate at 1 year after radiofrequency ablation was similar to the baseline value in 26 patients with bilateral kidneys (P = .14), it was decreased significantly in six patients with a single kidney (P = .03). Tumor enhancement disappeared after a single radiofrequency session in 31 patients and after two radiofrequency sessions in the other two patients (rates of primary and secondary technique effectiveness, 94% [31 of 33] and 100% [33 of 33], respectively). No local tumor progression was found during the mean follow-up of 20.0 months (range, 11.6-27.6 months). The respective 1-year overall and RCC-related survival rates were 97% (95% confidence interval: 91%, 100%) and 100%. Radiofrequency ablation with a multiple-electrode switching system is safe and effective for treatment of RCCs. However, further study is warranted to determine whether this technology is superior to other previously described methods.

Abstract No. 275: Radiofrequency ablation of renal cell carcinoma using a multiple electrode switching system: a phase-II clinical study

Abstract No. 275: Radiofrequency ablation of renal cell carcinoma using a multiple electrode switching system: a phase-II clinical study

Radiofrequency Ablation: Simultaneous Application of Multiple Electrodes via Switching Creates Larger, More Confluent Ablations than Sequential Application in a Large Animal Model

To compare radiofrequency (RF) ablations created by using a sequential technique to those created simultaneously by using a switching algorithm in ex vivo and in vivo liver models.RF ablation was performed by using either sequential or switched application of three cooled electrodes in a 2-cm triangular array in ex vivo bovine liver (28 total ablations) and in vivo swine liver (12 total ablations) models. For sequential ablations, electrodes were powered for 12 minutes each with a 5-minute rest interval between activations to simulate electrode repositioning. Switched ablations were created by using a multiple-electrode switching system for 12 minutes. Temperatures were measured during ex vivo experiments at four points in the ablation zone. Ablation zones were measured for minimum and maximum diameter, cross-sectional area, and isoperimetric ratio. Mann-Whitney and Wilcoxon matched pairs tests were used to identify differences between groups.The switched application created larger and more circular zones of ablation than did the sequential application, with mean (+/-standard deviation) ex vivo cross-sectional areas of 25.4 cm(2) +/- 5 .3 and 18.8 cm(2) +/- 6.6 (P = .001), respectively, and mean in vivo areas of 17.1 cm(2) +/- 5.1 and 13.2 cm(2) +/- 4.2 (P < .05). Higher temperatures and more rapid heating occurred with the switched application; switched treatments were 74% faster than sequential treatments (12 vs 46 minutes). In the sequential group, subsequent ablations grew progressively larger due to local ischemia.Switched application of three electrodes creates larger, more confluent ablations in less time than sequential application. Thermal synergy and ablation-induced ischemia both substantially influence multiple-electrode ablations.