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Purpose: The purpose of this study was to retrospectively determine the incidence of early enlarging cavitation after percutaneous radiofrequency ablation (RFA) of lung tumor and identify risk factors associated with their occurrence., Patients and Methods: A total of 245 patients (140 men, 105 women; mean age, 62.7 ± 11.8 [SD] years; age range: 31-87 years) with 605 lung tumors who were treated using 401 RFA sessions from April 2010 to March 2020 were included. Of which, 31 patients with 38 early enlarging cavitation and control group (151 patients with 228 tumors) were analyzed. Early enlarging cavitation was defined as cavities with an enlarged size (>3 cm) occurring on ablated lesions within seven days after RFA. Incidence of cavitation, risk and post-procedural factors of occurrence, major adverse events (AEs) that occurred in RFA sessions with cavitation, and course of cavitation were evaluated. AEs were classified using the CIRSE classification system for complications., Results: Thirty-eight cavities (6.3%, 38/605 tumors) in 31 patients occurred in an average of 3.1 ± 1.7 days (range, 1-7 days) after 32 RFA sessions. Distance from pleura ≥ 20 mm, contact with vessel ≥ 3 mm, multitined expandable electrode ≥ 3 cm, and bronchus ≥ 2 mm encompassed in the ablation zone were independent risk factors of occurrence. Fever ≥ 38.5 °C, white blood cell count ≥ 10,000/μl one day after RFA, and steroid therapy were independent post-procedural factors of occurrence. Twenty-four Grade 3 and two Grade 6 AEs occurred. Twenty-nine cavities disappeared within a mean duration of 111.9 ± 64.9 (SD) days (range: 44-274 days) and four remained with a mean follow-up of 279.2 ± 174 (SD) days; five patients were lost to follow-up., Conclusions: Early enlarging cavitation occurs in 6.3% of lung tumors treated with RFA and are associated with 26 major AEs in 32 sessions. Aforementioned procedural factors and post-procedural inflammation were significant risk factors of occurrence., Competing Interests: Disclosure of Competing Interest The authors declare that they have no competing of interest., (Copyright © 2022 Société française de radiologie. Published by Elsevier Masson SAS. All rights reserved.)

To assess the feasibility of needle tract ablation in liver tissue in ex vivo and in vivo animal models using a cryo-probe and electrosurgical device. The experimental device is made by inserting a cryoprobe through an intro-ducer sheath for insulation, with 2-cm of probe tip projecting out. A beagle liver was punctured by the device, and electric current was applied at 30-W with the electrosurgical knife touching the non-insulated device base. The discolored area of cut surface along the device was evaluated in 5 application-time groups (5 , 10 , 15 , 20, or 25 seconds). An ex vivo experiment was performed to determine an ablation algorithm with an appropriate application time by comparison with radiofrequency ablation (RFA) results. Thereafter, an in vivo experiment was performed to verify the algorithm's feasibility. In the ex vivo model, the cut surface demonstrated different amounts of discolored area according to the application time. The total discolored area in the 20-seconds group was similar to that by RFA. In the in vivo model, the liver did not bleed, the total discolored area was similar to that ex vivo, and coagulation necrosis was confirmed by photomicrograph. Needle tract ablation can be per-formed using the experimental device and electrosurgical device., Competing Interests: No potential conflict of interest relevant to this article was reported.

Objective: To evaluate the accuracy of robotic insertion of various ablation needles at various locations under computed tomography (CT) guidance in swine., Materials and Methods: The robot was used for CT-guided insertion of four ablation needles, namely a single internally cooled radiofrequency ablation (RFA) needle (Cool-tip), a multi-tined expandable RFA needle (LeVeen), a cryoablation needle (IceRod), and an internally cooled microwave ablation needle (Emprint). One author remotely operated the robot with the operation interface in order to orient and insert the needles under CT guidance. Five insertions of each type of ablation needle towards 1.0-mm targets in the liver, kidney, lung, and hip muscle were attempted on the plane of an axial CT image in six swine. Accuracy of needle insertion was evaluated as the three-dimensional length between the target centre and needle tip. The accuracy of needle insertion was compared according to the type of needle used and the location using one-way analysis of variance., Results: The overall mean accuracy of all four needles in all four locations was 2.8 mm. The mean accuracy of insertion of the Cool-tip needle, LeVeen needle, IceRod needle, and Emprint needle was 2.8 mm, 3.1 mm, 2.5 mm, and 2.7 mm, respectively. The mean accuracy of insertion into the liver, kidney, lung, and hip muscle was 2.7 mm, 2.9 mm, 2.9 mm, and 2.5 mm, respectively. There was no significant difference in insertion accuracy among the needles (P = .38) or the locations (P = .53)., Conclusion: Robotic insertion of various ablation needles under CT guidance was accurate regardless of type of needle or location in swine., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Purpose: A prospective multicenter phase I/II trial was performed to evaluate the clinical safety and efficacy of radiofrequency ablation (RFA) for metastatic bone tumors., Materials and Methods: Thirty-three patients (27 men, 6 women, mean age 61 years) with metastatic bone tumors were enrolled. In phase I, nine patients were enrolled, and the safety of RFA was evaluated. In phase II, 23 patients were included, and an intent-to-treat analysis was performed. The primary endpoint was to evaluate the treatment's safety. The secondary endpoint was to evaluate the efficacy of pain relief at 1 week after RFA., Results: RFA was performed in 32 of 33 enrolled patients. No serious complications were observed during the phase I, so phase II was performed. Four patients exhibited adverse events, including one case each of Grade 3 pain and, Grade 2 hypotension, and one patient developed Grade 1 burns at the grounding pad and puncture site. One patient died of liver failure on day 7 after RFA due to the progression of the primary lesion. The efficacy was excellent (no increase in analgesic dosage, post-RFA VAS score of 0-2 or decreased by not less than 5 compared to before RFA) in 20 patients (60.6%), good (no increase in analgesic dosage, post-RFA VAS score decreased by not less than 2 but by < 5 compared to before RFA) in 3 (9.1%), and poor in 10 patients (30.3%). Thus, the response rate was 69.7%., Conclusion: RFA is a safe and effective method for treating painful metastatic bone tumors.

Purpose: This retrospective, single-center study evaluated radiofrequency (RF) ablation for pulmonary metastases of sarcoma., Materials and Methods: Forty-six patients with sarcoma (144 pulmonary metastases) underwent 88 RF ablation sessions. Data regarding local tumor progression, efficacy, procedural adverse events (AEs; National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0), overall survival (OS), and OS-associated prognostic factors were retrospectively evaluated using univariate analyses., Results: Local progression occurred in 22 of 144 tumors (15.3%). Primary and secondary efficacy rates were 83.5 and 90.0% at 1 year and 76.3 and 81.4% at 2 years, respectively. Seventy-three grade 1 AEs, 33 grade 2 AEs, and no grade ≥ 3 AEs were observed. Twenty-eight patients (60.9%) remained alive and 18 died, yielding 1-, 2-, and 3-year OS rates of 80.6, 70.1, and 47.1% (median survival time, 31.7 months). Univariate analysis revealed extrapulmonary metastasis (P = 0.005), noncurative RF ablation (P = 0.009), and a post-RF ablation disease-free interval of ≤12 months (P = 0.015) as significant negative prognostic factors., Conclusion: RF ablation is safe, offers good local control, and may be a viable treatment option for pulmonary metastasis of sarcoma.

Objective: The goal of this study was to retrospectively evaluate the outcome, including feasibility, safety, diagnostic yield, and factors affecting the success of computed tomography fluoroscopy-guided biopsy when performed during the same procedure than radiofrequency ablation (RFA) in renal tumors strongly suspected of being T1a renal cell carcinoma (RCC)., Materials and Methods: Nineteen patients (13 men, 6 women; mean age, 66.7 years) with a total of 19 suspected renal tumors (mean diameter, 1.8cm) underwent computed tomography fluoroscopy-guided biopsy during (n=6) or immediately after (n=13) RFA. All patients were strongly suspected of having RCC on the basis of patient's medical histories and/or the results of imaging investigations. All procedures were divided into diagnostic and non-diagnostic biopsies. Various variables were compared between the 2 groups using univariate analysis., Results: In all tumors, biopsy procedures were technically feasible. No major complications were observed, except for 8 minor post-procedural bleedings. All but one tumor was completely ablated. Local recurrence in the ablation zone as well as tumor seeding in retroperitoneal fat occurred in 1 patient 8.5months after the procedure and were successfully treated with further percutaneous cryoablation. Thirteen tumors were diagnosed as RCC, whereas 6 were ultimately found to contain normal renal tissue (n=5) or connective tissue (n=1). Univariate analysis revealed that none of the variables were significantly different between the diagnostic and non-diagnostic biopsies., Conclusion: The performance of renal tumor biopsy and RFA in the same session is feasible and safe. Although pre-treatment pathological diagnosis would be generally desirable, simultaneous biopsy with RFA can be an option for the patients who are not amenable to pre-treatment biopsy., (Copyright © 2016 Editions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.)

Purpose: This multicenter prospective study was conducted to evaluate the safety and efficacy of percutaneous radiofrequency ablation (RFA) for painful osteoid osteoma (OO)., Materials and Methods: Patients with OO (femur: n = 17, tibia: n = 2, humerus: n = 1, rib: n = 1) were enrolled and treated with RFA. In phase I, nine patients were evaluated for safety. In phase II, 12 patients were accrued, and an intent-to-treat analysis was performed on all patients. The primary endpoint was to evaluate the treatment safety. The secondary endpoint was to evaluate the efficacy for pain relief by the visual analogue scale (VAS) at 4 weeks after RFA. Treatment efficacy was classified as significantly effective (SE) when VAS score decreased by ≥5 or score was <2, moderately effective when VAS score decreased by <5-≥2 and score was ≥2, and not effective (NE) when VAS score decreased by <2 or score was increased. Cases where the need for analgesics increased after treatment were also NE., Results: RFA procedures were completed in all patients. Minor adverse effects (AEs) were observed as 4.8-14.3 % in 12 patients, and no major AEs were observed. Mean VAS score was 7.1 before treatment, 1.6 at 1 week, 0.3 at 4 weeks, and 0.2 at 3 months. All procedures were classified as SE. Pain recurrence was not noted in any patient during follow-up (mean: 15.1 months)., Conclusion: RFA is a safe, highly effective, and fast-acting treatment for painful extraspinal OO. Future studies with a greater number of patients are needed.

Purpose: To conduct a retrospective evaluation of long-term survival after radiofrequency (RF) ablation for lung oligometastases from 5 types of primary lesions., Materials and Methods: The study population consisted of 123 patients with lung oligometastases from colorectal cancer (CRC), non-small-cell lung cancer, hepatocellular carcinoma, esophageal cancer, and renal-cell carcinoma treated with RF ablation. Lung oligometastases were defined as 1-5 metastases confined to the lung while the primary cancer and other metastases were eradicated. Overall survival (OS) and recurrence-free survival (RFS) were estimated for the overall study population and for patients with each type of primary lesion. The OS and RFS rates were compared with those of the patients with any of the other four primary lesion types. Finally, various variables were analyzed to determine what factors influenced OS and RFS., Results: The median follow-up was 45.7 months, and the 5-year OS and RFS rates for all 123 patients were 62% and 25%, respectively. The OS time for patients with metastases from CRC was significantly longer (P = .042); it was significantly shorter (P = .022) in patients with metastases from esophageal cancer. Longer disease-free interval was significantly (P = .015) associated with better OS. There was no variable significantly associated with OS and RFS on multivariate analyses., Conclusions: Data from this single-center study appear promising in terms of long-term survival after RF ablation of lung oligometastases from 5 primary lesions., (Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.)

Objective: The aim of this study was to evaluate radiofrequency ablation (RFA) of lung tumors with dual-energy computed tomography while focusing on tumor composition and lung perfusion., Methods: The 36 tumors in 25 patients were included. Dual-energy computed tomography was performed before RFA and at 2 days and 1, 3, and 6 months thereafter. The effective atomic number (Zeff) of the tumors before RFA was compared with the Zeff at each follow-up using the paired t test. Lung perfusion was evaluated by iodine map images. When decreased perfusion was suspected after RFA, lung perfusion scintigraphy was performed., Results: The mean Zeff of the tumors significantly (P < 0.001) decreased at each follow-up, compared with that before RFA. Lung perfusion in the parenchyma peripheral to the tumors appeared to decrease at 2 days in 9 tumors, which was confirmed by scintigraphy in 7 tumors., Conclusions: Dual-energy computed tomography was useful by providing additional information on tumor composition and lung perfusion.

The present single center prospective phase II clinical trial is designed to evaluate the efficacy and safety of percutaneous radiofrequency (RF) ablation for colorectal lung metastases. Patients who have colorectal lung metastases without extrapulmonary metastases are included in this study. The primary endpoint is 3-year overall survival (OS) after RF ablation. The secondary endpoints are the prevalence of adverse events within 4 weeks, local tumor progression rate, 1- and 5-year OS, cause-specific survival, and relapse-free survival. The recruitment of patients commenced in July 2014, and the enrolment of 45 patients is intended over the 3 years of study period.

Purpose: This prospective multicenter study aimed to evaluate the efficacy and safety of percutaneous radiofrequency (RF) ablation for lung cancer., Materials and Methods: From May 2008 to April 2012, 33 patients (26 men, 7 women; mean age 70.5 years) were enrolled. RF ablation was performed using an internally cooled or expandable multitined electrode. The primary endpoint was complete response (CR) determined using (18)F fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) performed 6 months after RF ablation. The secondary endpoint was the incidence and grade of adverse events (AEs) evaluated using the Common Toxicity Criteria for Adverse Events, version 3.0., Results: All patients underwent RF ablation and had efficacy analyses evaluated; however, FDG-PET/CT images before RF ablation were not available for two patients. The CR rate was 68 % (21 of 31 patients). One patient had a grade 5 AE unrelated to RF ablation. Grade ≥3 AEs occurred in 12 % of patients. During the follow-up period (median 37 months; range 1-55 months), five patients developed local tumor progression and nine (29 %) died. Overall survival at 1, 2, and 3 years was 97, 82, and 74 %, respectively., Conclusion: Percutaneous RF ablation is a safe, feasible, and effective treatment for small malignant lung tumors.

Introduction: Computed tomography (CT) fluoroscopy-guided renal cryoablation and lung radiofrequency ablation (RFA) have received increasing attention as promising cancer therapies. Although radiation exposure of interventional radiologists during these procedures is an important concern, data on operator exposure are lacking., Materials and Methods: Radiation dose to interventional radiologists during CT fluoroscopy-guided renal cryoablation (n = 20) and lung RFA (n = 20) was measured prospectively in a clinical setting. Effective dose to the operator was calculated from the 1-cm dose equivalent measured on the neck outside the lead apron, and on the left chest inside the lead apron, using electronic dosimeters. Equivalent dose to the operator's finger skin was measured using thermoluminescent dosimeter rings., Results: The mean (median) effective dose to the operator per procedure was 6.05 (4.52) μSv during renal cryoablation and 0.74 (0.55) μSv during lung RFA. The mean (median) equivalent dose to the operator's finger skin per procedure was 2.1 (2.1) mSv during renal cryoablation, and 0.3 (0.3) mSv during lung RFA., Conclusion: Radiation dose to interventional radiologists during renal cryoablation and lung RFA were at an acceptable level, and in line with recommended dose limits for occupational radiation exposure.

We retrospectively evaluated the safety and efficacy of artificial pneumothorax induction to perform computed tomography (CT)-guided radiofrequency ablation (RFA) for sub-diaphragm hepatocellular carcinomas (HCCs). From June 2008 to October 2010 at our institution, 19 HCCs (16 patients) were treated using CT-guided RFA after artificial pneumothorax induction. A 23-G needle was inserted into the liver surface at a site of 2 connected pleurae without lung tissue. After a small amount of air was injected, the pleural space widened, creating a small pneumothorax. Additional air was insufflated via a newly inserted 18-G cannula to raise the lung away from the planned puncture line for RFA. The electrode was then advanced transthoracically. Ablation was performed using a cool-tip electrode with manual impedance control mode. The injected air was then aspirated as much as possible. Artificial pneumothorax was successfully induced in all cases. The average total volume of injected air in each case was 238ml. No artificial pneumothorax-related complication occurred; lung injury occurred in one case during RF electrode insertion. No local progression occurred during follow-up. Recurring HCCs were observed in eight patients. Artificial pneumothorax induction is safe and effective for CT-guided RFA of sub-diaphragm HCCs, which are difficult to locate on US.

Purpose: This multicenter phase I/II study evaluated the safety, feasibility, and initial efficacy of radiofrequency ablation (RFA) for small malignant renal tumors., Methods: Thirty-three patients were enrolled in the study. A single session of RFA was performed in patients with a renal tumor of 1-3 cm in greatest diameter, with the exception of lesions adjacent to the renal hilum. The primary endpoint was the safety of renal RFA, and the secondary endpoints were its feasibility and initial efficacy for local control, as well as the incidence and grade of adverse events. Clinical efficacy was evaluated by CT scans within 1 week and at a further 4 weeks after the procedure using the criteria adapted from the Response Evaluation Criteria in Solid Tumors., Results: The RFA procedure was completed in 100% (95% confidence interval [CI] 89-100%) of all 33 patients. There were no severe adverse events (0% [95% CI 0-11%]). Among the 33 patients, a complete response, partial response, progressive disease, and stable disease were seen in 28 (85%), 0 (0%), one (3%), and one (3%) patient(s), respectively, with a tumor response rate of 85% [95% CI 68-95%]). Three patients (9%), including one ineligible patient (3%), were not evaluable. Out of 30 evaluable patients, a complete response was achieved in 28 (93%)., Conclusion: The current multicenter trial revealed that RFA is a safe, feasible, and effective treatment for small malignant renal tumors in patients who are not candidates for surgery.

Purpose: To retrospectively investigate the impact of the electrode array diameter on local tumor progression after lung radiofrequency ablation., Materials and Methods: This study included 651 lung tumors treated using multitined expandable electrodes and followed for ≥ 6 months. The mean long-axis tumor diameter was 12 mm ± 7 (range, 2-42 mm). The difference between electrode array diameter and tumor diameter (DAT) was used to investigate the impact of the electrode array diameter. All tumors were classified into 2 groups according to various variables including DAT (≥ 10 mm or < 10 mm). The primary technique efficacy rates were calculated using Kaplan-Meier analysis and compared between the 2 groups of each variable using the log-rank test. In addition, crude and multivariate multilevel survival analyses were performed by sequentially including DAT and the other variables in 5 models., Results: The median DAT for 651 tumors was 12 mm (range, -15 to 24 mm). The technique efficacy rate was significantly lower in the < 10 mm DAT group than in the ≥ 10 mm group (P < .001). In the crude and multivariate multilevel survival analyses, < 10 mm DAT was a significant risk factor for local progression in all models except model 5 (P = .067). In the ≥ 10 mm group, the technique efficacy rates were not significantly different between the 2 ≥ 10 mm DAT subgroups (10 to <15 mm DAT vs ≥ 15 mm DAT)., Conclusions: DAT is an important risk factor for local progression. We recommend an electrode that is ≥ 10 mm larger than the tumor diameter., (Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.)

Purpose: To prospectively investigate the incidence of post-lung radiofrequency (RF) ablation fever as well as its associated factors, according to the grade of fever., Materials and Methods: A total of 56 patients who underwent 67 lung RF sessions were analyzed. Post-ablation fever (≥ 37.0°C) was graded according to the common toxicity criteria of adverse events v. 4.0. Fever ≥ 37.0°C and <38.0°C was defined as grade 0 fever. The 67 RF sessions were divided into two groups according to the presence of post-ablation fever, and the factors associated with fever were determined using univariate and multivariate analyses. Subsequently, the RF sessions accompanied by post-ablation fever were further divided into two groups according to the grade of fever (grade 0 vs. grade ≥ 1), and the factors associated with the grade of fever were determined., Results: Grade 0, 1, and 2 fever accompanied 36 (54%), 11 (16%), and 2 (3%) sessions, respectively. Post-ablation fever was significantly associated with larger ablated parenchymal volume (P=0.001) and development of pulmonary infiltration (P=0.004). Additionally, development of pulmonary infiltration (P=0.048) was also significantly and independently associated with higher grade of fever in the multivariate analysis., Conclusions: The incidences of grade 0, 1, and 2 post-ablation fever were 54%, 16%, and 3%, respectively. Larger ablated parenchymal volume and development of pulmonary infiltration were found to be associated with the development of post-ablation fever, with the latter being an independent factor associated with higher grade of fever., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To retrospectively evaluate radiofrequency (RF) ablation of lung tumors performed via the transosseous approach., Materials and Methods: Twelve lung tumors (mean diameter, 1.0 cm; range, 0.4-1.6 cm) in 12 patients were treated by RF ablation via a transscapular and/or transrib route with the use of a bone biopsy needle under computed tomographic fluoroscopy guidance. Therapeutic outcomes evaluated included feasibility, safety, and local efficacy. Complications were assessed based on the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0., Results: The transosseous route was successfully employed in all patients, and the electrode was successfully advanced into all tumors with this approach. The mean distance of penetrated bone was 0.57 cm (range, 0.19-1.16 cm). Complications occurred in eight RF ablation sessions, including six grade 1 events (two cases of pneumothorax and one case each of asymptomatic rib fracture 6 mo after treatment, neuralgia, pulmonary hemorrhage, and hemothorax), two grade 2 events (pneumonia and high fever), and one grade 3 event (pneumothorax requiring pleurodesis). No adverse events of grade ≥ 4 occurred. The mean and median tumor follow-up periods were 19.5 and 15.2 mo (range, 3.0-41.5 mo). Local progression occurred in two cases at 3 and 12 mo after treatment and was successfully treated with a second RF ablation procedure. The technique efficacy rates were 91.7% at 6 mo, 81.5% at 1 y, and 81.5% at 2 y., Conclusions: The transosseous approach was feasible in computed tomographic fluoroscopy-guided RF ablation of select lung tumors when no other option was available., (Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.)

Purpose: To retrospectively evaluate the outcomes of radiofrequency (RF) ablation of lung metastases from head and neck adenoid cystic carcinoma (ACC)., Materials and Methods: Nine patients (two men and seven women; mean age, 61.6 y) with 45 lung metastases (mean diameter, 1.1 cm; range, 0.4-2.7 cm) from head and neck ACC underwent RF ablation in 30 sessions. Primary endpoints were technical success, technique effectiveness, and procedural complications. Secondary endpoints included overall survival (OS)., Results: RF ablation was technically successful for all 45 metastases. The median tumor follow-up period was 37.1 months (range, 12.9-128.3 mo). Local progression occurred in six tumors, two of which were treated again and subsequently showed complete response. Major complications (pneumothorax requiring chest tube placement) occurred in five sessions (16.7%). The median patient follow-up period was 61.6 months (range, 20.5-134.5 mo). Two patients died of disease progression at 38.9 and 61.6 months after RF ablation, respectively, whereas the other seven remained alive at the end of the study. OS rates from the initial RF ablation were 100% at 3 years and 83.3% at 5 years (mean survival time, 106.4 mo). OS rates from the treatment of the primary site were 100% at 5 years and 62.5% at 10 years (mean survival time, 210.1 mo)., Conclusions: Radiofrequency ablation is an acceptable and effective local treatment for lung metastases from head and neck ACC. However, further study is needed to evaluate its effect on patient survival., (Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.)

Purpose: We retrospectively evaluated the outcomes of lung cancer patients presenting with ground-glass opacity (GGO) who received radiofrequency ablation (RFA)., Methods: Sixteen patients (5 men and 11 women; mean age, 72.6 years) with 17 lung cancer lesions showing GGO (mean long axis diameter, 1.6 cm) underwent a total of 20 percutaneous computed tomography (CT) fluoroscopy-guided RFA sessions, including three repeated sessions for local progression. Lung cancer with GGO was defined as a histologically confirmed malignant pulmonary lesion with a GGO component accounting for >50 % of the lesion on high-resolution CT. Procedure outcomes were evaluated., Results: There were no major complications. Pneumothorax occurred in 15 of 20 treatment sessions: 14 were asymptomatic, and 1 required chest tube placement but resolved satisfactorily within 48 h. Minor pulmonary hemorrhage occurred in two and mild pneumonitis in one. The median tumor follow-up period was 61.5 (range 6.1-96.6) months. The effectiveness rates of the primary and secondary techniques were 100 and 100 % at 1 year, 93.3 and 100 % at 2 years, and 78.3 and 92.3 % at 3 years, respectively. The median patient follow-up period was 65.6 (range 6.1-96.6) months. One patient died owing to recurrent other cancer 11.7 months after RFA, whereas the other 15 remained alive. Overall survival and disease-specific survival rates were 93.3 and 100 % at 1 year and 93.3 and 100 % at 5 years, respectively., Conclusions: RFA for lung cancer with GGO was safe and effective, and resulted in promising survival rates.

Purpose: To retrospectively evaluate long-term survival outcomes of radiofrequency (RF) ablation of colorectal lung metastases and evaluate factors associated with improved survival., Materials and Methods: Eighty-four patients (46 male and 38 female; median age, 65 y) with 172 colorectal lung metastases (median size, 1.2 cm) underwent 113 RF ablation sessions. Thirteen patients had viable extrapulmonary recurrences at the time of RF ablation. The primary endpoint was patient survival. Prognostic factors associated with survival were determined by univariate and multivariate analyses. Secondary endpoints were local tumor progression and adverse events (per National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0)., Results: During follow-up (median duration, 37.5 mo), 36 patients (42.9%) died. The estimated overall survival (OS) rates were 95.2%, 65.0%, and 51.6% at 1, 3, and 5 years, respectively (median OS time, 67.0 mo). Multivariate analysis revealed that a carcinoembryonic antigen (CEA) level of at least 5 ng/mL before RF ablation (P = .03) and the presence of viable extrapulmonary recurrences at the time of RF ablation (P = .001) were independent negative prognostic factors. The local tumor progression rate was 14.0% (24 of 172 tumors). Grade 3 adverse events were observed after two sessions (1.8%), and grade 4/5 adverse events were not observed., Conclusions: RF ablation of colorectal lung metastases provided favorable long-term survival with a low incidence of severe adverse events. Independent prognostic factors were a high CEA level before RF ablation and the presence of viable extrapulmonary recurrences at the time of RF ablation., (Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate retrospectively outcomes after radiofrequency (RF) ablation for pulmonary metastases from esophageal cancer., Materials and Methods: This study included 21 consecutive patients who met inclusion criteria (all men; mean age, 66.0 y) and had pulmonary metastases from esophageal cancer. There were 31 tumors (mean size, 1.7 cm) that were treated with 27 planned ablation sessions. At the initial RF ablation sessions, 3 patients had viable extrapulmonary recurrences, and 18 patients had viable recurrences confined to the lung. Primary study endpoints included patient survival and the determination of prognostic factors. Secondary endpoints included local efficacy and safety of the treatment. The log-rank test was used to identify prognostic factors. Adverse events were evaluated according to the National Cancer Institute Common Terminology Criteria for Adverse Events Version 4.0., Results: Median follow-up duration after the initial RF ablation was 22.4 months (range, 6.2-76.1 mo). Estimated overall survival rates were 85.7% at 1 year, 54.8% at 2 years, and 38.4% at 3 years after the initial RF ablation session. The presence of viable extrapulmonary recurrences at the initial RF ablation session was an unfavorable prognostic factor (P < .001). Local tumor progression was observed in 25.8% (8 of 31) of tumors and occurred 2.6-10.0 months (median, 4.8 mo) after RF ablation. Grade 3 adverse events occurred in 7.4% (2 of 27) of sessions, including pleural effusion requiring chest tube placement and pneumoderma requiring surgical intervention. No grade 4 or greater adverse events occurred., Conclusions: RF ablation is a promising treatment option for patients with pulmonary metastases from esophageal cancer., (Copyright © 2014 SIR. Published by Elsevier Inc. All rights reserved.)

Radiofrequency ablation (RFA) causes focal coagulation necrosis in tissue. Its first clinical application was reported in 2000, and RFA has since been commonly used in both primary and metastatic lung cancer. The procedure is typically performed using computed tomography guidance, and the techniques for introducing the electrode to the tumor are simple and resemble those used in percutaneous lung biopsy. The most common complication is pneumothorax, which occurs in up to 50% of procedures; chest tube placement for pneumothorax is required in up to 25% of procedures. Other severe complications, such as pleural effusion requiring chest tube placement, infection, and nerve injury, are rare. The local efficacy depends on tumor size, and local progression after RFA is not rare, occurring in 10% or more of patients. The local progression rate is particularly high for tumors > 3 cm. Repeat RFA may be used to treat local progression. Short- to mid-term survival after RFA appears promising and is approximately 85%-95% at 1 year and 45%-55% at 3 years. Long-term survival data are sparse. Better survival may be expected for patients with small metastasis, low carcinoembryonic antigen levels, and/or no extrapulmonary metastasis. The notable advantages of RFA are that it is simple and minimally invasive; preserves pulmonary function; can be repeated; and is applicable regardless of previous treatments. Its most substantial limitation is limited local efficacy. Although surgery is still the method of choice for treatment with curative intent, the ultimate application of RFA may be to replace metastasectomy for small metastases. Randomized trials comparing RFA with surgery are needed.

This review examines studies of radiofrequency ablation (RFA) of nonsmall cell lung cancer (NSCLC) and discusses the role of RFA in treatment of early-stage NSCLC. RFA is usually performed under local anesthesia with computed tomography guidance. RFA-associated mortality, while being rare, can result from pulmonary events. RFA causes pneumothorax in up to 63% of cases, although pneumothorax requiring chest drainage occurs in less than 15% of procedures. Other severe complications are rare. After RFA of stage I NSCLC, 31-42% of patients show local progression. The 1-, 2-, 3-, and 5-year overall survival rates after RFA of stage I NSCLC were 78% to 100%, 53% to 86%, 36% to 88%, and 25% to 61%, respectively. The median survival time ranged from 29 to 67 months. The 1-, 2-, and 3-year cancer-specific survival rates after RFA of stage I NSCLC were 89% to 100%, 92% to 93%, and 59% to 88%, respectively. RFA has a higher local failure rate than sublobar resection and stereotactic body radiation therapy (SBRT). Therefore, RFA may currently be reserved for early-stage NSCLC patients who are unfit for sublobar resection or SBRT. Various technologies are being developed to improve clinical outcomes of RFA for early-stage NSCLC.

We retrospectively evaluated the accumulation of fluorodeoxy glucose (FDG) in pulmonary malignancies without local recurrence during 2-year follow-up on positron emission tomography (PET)/computed tomography (CT) after radiofrequency ablation (RFA). Thirty tumors in 25 patients were studied (10 non-small cell lung cancers;20 pulmonary metastatic tumors). PET/CT was performed before RFA, 3 months after RFA, and 6 months after RFA. We assessed the FDG accumulation with the maximum standardized uptake value (SUVmax) compared with the diameters of the lesions. The SUVmax had a decreasing tendency in the first 6 months and, at 6 months post-ablation, FDG accumulation was less affected by inflammatory changes than at 3 months post-RFA. The diameter of the ablated lesion exceeded that of the initial tumor at 3 months post-RFA and shrank to pre-ablation dimensions by 6 months post-RFA. SUVmax was more reliable than the size measurements by CT in the first 6 months after RFA, and PET/CT at 6 months post-RFA may be more appropriate for the assessment of FDG accumulation than that at 3 months post-RFA.

Purpose: The purpose of this study was to evaluate altered pulmonary function retrospectively after RFA., Methods: This retrospective study comprised 41 ablation sessions for 39 patients (22 men and 17 women; mean age, 64.8 years). Vital capacity (VC) and forced expiratory volume in 1 s (FEV(1)) at 1 and 3 months after RFA were compared with the baseline (i.e., values before RFA). To evaluate the factors that influenced impaired pulmonary function, univariate analysis was performed by using multiple variables. If two or more variables were indicated as statistically significant by univariate analysis, these variables were subjected to multivariate analysis to identify independent factors., Results: The mean VC and FEV(1) before RFA and 1 and 3 months after RFA were 3.04 and 2.24 l, 2.79 and 2.11 l, and 2.85 and 2.13 l, respectively. The values at 1 and 3 months were significantly lower than the baseline. Severe pleuritis after RFA was identified as the independent factor influencing impaired VC at 1 month (P = 0.003). For impaired FEV(1) at 1 month, only severe pleuritis (P = 0.01) was statistically significant by univariate analysis. At 3 months, severe pleuritis (VC, P = 0.019; FEV(1), P = 0.003) and an ablated parenchymal volume ≥20 cm(3) (VC, P = 0.047; FEV(1), P = 0.038) were independent factors for impaired VC and FEV(1)., Conclusions: Pulmonary function decreased after RFA. RFA-induced severe pleuritis and ablation of a large volume of marginal parenchyma were associated with impaired pulmonary function.

Objective: We retrospectively evaluated the effect of transpulmonary radiofrequency ablation (RFA) of liver tumours on the lung., Methods: 16 patients (10 males and 6 females; mean age, 65.2 years) with 16 liver tumours (mean diameter 1.5 cm) underwent transpulmonary RFA under CT fluoroscopic guidance. The tumours were either hepatocellular carcinoma (n=14) or liver metastasis (n=12). All 16 liver tumours were undetectable with ultrasonography. The pulmonary function values at 3 months after transpulmonary RFA were compared with baseline (i.e. values before RFA)., Results: In 8 of 16 sessions, minor pulmonary complications occurred, including small pneumothorax (n=8) and small pleural effusion (n=1). In two sessions, major pulmonary complications occurred, including pneumothorax requiring a chest tube (n=2). These chest tubes were removed at 4 and 6 days, and these patients were discharged 7 and 10 days after RFA, respectively, without any sequelae. The pulmonary function values we evaluated were forced expiratory volume in 1 s (FEV1.0) and vital capacity (VC). The mean values of FEV1.0 before and 3 months after RFA were 2.55 l and 2.59 l, respectively; the mean values of VC before and 3 months after RFA were 3.20 l and 3.27 l, respectively. These pulmonary values did not show any significant worsening (p=0.393 and 0.255 for FEV1.0 and VC, respectively)., Conclusion: There was no significant lung injury causing a fatal or intractable complication after transpulmonary RFA of liver tumours.

Radiofrequency ablation has been applied as a minimally invasive therapy for the local control of lung tumors, including primary and metastatic neoplasms. Hemorrhagic complications after radiofrequency ablation can usually be treated conservatively, but such complications can be massive and fatal in some cases. In this paper, we report the rare case of delayed massive hemothorax caused by the rupture of a pulmonary artery pseudoaneurysm after lung radiofrequency ablation that was treated using transcatheter coil embolization followed by a left lower lobectomy. A 75-year-old woman underwent radiofrequency ablation for the treatment of a metastatic lung tumor in the left lower lobe arising from a colorectal carcinoma located close to a branch of the pulmonary artery. Thirty-six hours later, hemothorax and hemorrhagic shock occurred as a result of a ruptured pulmonary artery pseudoaneurysm and radiofrequency ablation-induced damage to the interlobular pleura. After transcatheter coil embolization of the pulmonary artery pseudoaneurysm, she recovered from a state of shock and a left lower lobectomy was performed. Histological findings revealed the presence of residual tumor cells in the ablated lung tumor. The postoperative course was uneventful, and no evidence of recurrence of the primary disease was seen at 1 year after the surgery. Although hemothorax secondary to the rupture of a pulmonary artery pseudoaneurysm after lung radiofrequency ablation is a rare complication, it should be recognized as a serious potential complication of lung radiofrequency ablation for a tumor located close to the pulmonary artery branch.

Purpose: To retrospectively investigate the incidence of and risk factors for phrenic nerve injury after radiofrequency (RF) ablation of lung tumors., Materials and Methods: The study included 814 RF ablation procedures of lung tumors. To evaluate the development of phrenic nerve injury, chest radiographs obtained before and after the procedure were examined. Phrenic nerve injury was assumed to have developed if the diaphragmatic level was elevated after the procedure. To identify risk factors for phrenic nerve injury, multiple variables were compared between cases of phrenic nerve injury and randomly selected controls by using univariate analyses. Multivariate analysis was then performed to identify independent risk factors., Results: Evaluation of phrenic nerve injury from chest radiographs was possible after 786 procedures. Evidence of phrenic nerve injury developed after 10 cases (1.3%). Univariate analysis revealed that larger tumor size (≥ 20 mm; P = .014), proximity of the phrenic nerve to the tumor (< 10 mm; P < .001), the use of larger electrodes (array diameter or noninsulated tip length ≥ 3 cm; P = .001), and higher maximum power applied during ablation (≥ 100 W; P < .001) were significantly associated with the development of phrenic nerve injury. Multivariate analysis demonstrated that the proximity of the phrenic nerve to the tumor (< 10 mm; P < .001) was a significant independent risk factor., Conclusions: The incidence of phrenic nerve injury after RF ablation was 1.3%. The proximity of the phrenic nerve to the tumor was an independent risk factor for phrenic nerve injury., (Copyright © 2012 SIR. Published by Elsevier Inc. All rights reserved.)

The present report describes three cases of a bronchiolitis obliterans organizing pneumonia (BOOP)-like reactive pneumonitis following radiofrequency (RF) ablation for lung cancer. The incidence of BOOP-like reactive pneumonitis after RF ablation at the authors' institution was estimated to be approximately 0.4% (three of 840 sessions). The patients presented with nonspecific symptoms. Computed tomography images showed consolidation or ground-glass opacity in a peripheral-dominant distribution and/or patchy air-space opacities. The disease was nonresponsive to antibiotic therapy but responded favorably to pulse therapy of steroids. BOOP-like reactive pneumonitis should be recognized as a complication following lung RF ablation., (Copyright © 2012 SIR. Published by Elsevier Inc. All rights reserved.)

The aim of the present study was to assess the diagnostic usefulness of Fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in the prediction of local recurrence of malignant lung tumors by analyzing the pre-radiofrequency ablation (RFA) maximal standardized uptake value (SUV(max)). We performed a historical cohort study of consecutive malignant lung tumors treated by RFA from January 2007 to May 2008 at Okayama University Hospital. We selected only lung tumors examined by PET/CT within 90 days before RFA and divided them (10 primary and 29 metastatic) into 3 groups according to their tertiles of SUV(max). We calculated recurrence odds ratios in the medium group and the high group compared to the low group using multivariate logistic analysis. After we examined the relationship between SUV(max) and recurrence in a crude model, we adjusted for some factors. Tumors with higher SUV(max) showed higher recurrence odds ratios (medium group; 1.84, high group; 4.14, respectively). The tumor size also increased the recurrence odds ratio (2.67); we thought this was mainly due to selection bias because we excluded tumors less than 10mm in diameter. This study demonstrated the pre-RFA SUV(max) in PET/CT may be a prognostic factor for local recurrence of malignant lung tumors.

The application of radiofrequency ablation for the treatment of lung cancer by our group at Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences began in June 2001, and in the present report, we review our 10-year experience with this treatment modality at Okayama University Hospital. The local efficacy of radiofrequency ablation for the treatment of lung cancer depends on tumor size and the type of electrode used, but not on tumor type. An important factor for the prevention of local failure may be the acquisition of an adequate ablative margin. The combination of embolization and radiation therapy enhances the local efficacy. Local failure may be salvaged by repeating the radiofrequency ablation, particularly in small tumors. Survival rates after radiofrequency ablation are quite promising for patients with clinical stage I non-small cell lung cancer and pulmonary metastasis from colorectal cancer, hepatocellular carcinoma, and renal cell carcinoma. The complications caused by radiofrequency ablation can be treated conservatively in the majority of cases. However, attention should be paid to rare but serious complications. This review shows that radiofrequency ablation is a promising treatment for patients with lung cancer.

Objective: This study aimed at retrospectively evaluating the outcomes of radiofrequency ablation of clinical stage I non-small cell lung cancer., Methods: This study was carried out on 50 nonsurgical candidates (29 men and 21 women; mean age, 74.7 years) with clinical stage I (IA, n = 38; IB, n = 12) histologically proven non-small cell lung cancer. A total of 52 tumors were treated with 52 ablation sessions. Radiofrequency ablation was performed percutaneously under computed tomography fluoroscopic guidance. The outcomes of radiofrequency ablation were evaluated, including toxicity, local efficacy, and patient survival. Toxicity was evaluated using the National Cancer Institute Common Terminology Criteria for Adverse Events Version 4.0. Local efficacy was evaluated by using computed tomography scan with a contrast medium. The overall, cancer-specific, and disease-free survivals were estimated with Kaplan-Meier analysis., Results: Grade 2 and 3 adverse events occurred after 6 (12%) and 3 (6%) of the 52 sessions, respectively. The median follow-up period was 37 months. Local progression was observed in 16 (31%) of the 52 tumors. The median survival time was 67 months. The overall, cancer-specific, and disease-free survivals were 94%, 100%, and 82% at 1 year, 86%, 93%, and 64% at 2 years, and 74%, 80%, and 53% at 3 years, respectively., Conclusions: Radiofrequency ablation of clinical stage I non-small cell lung cancer was minimally invasive and provided promising patient survival, although the local efficacy needs to be improved., (Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.)

Purpose: To retrospectively evaluate technical success, effectiveness, complications, patient survival, and prognostic factors with percutaneous radiofrequency (RF) ablation for pulmonary metastases resulting from hepatocellular carcinoma (HCC)., Materials and Methods: Thirty-two patients from six institutions were included, with a total of 83 pulmonary metastases treated in 65 sessions. RF ablation was always performed percutaneously with computed tomography (CT) guidance. Primary endpoints were technical success and technique effectiveness. Technique effectiveness was evaluated based on sequential follow-up CT images. Secondary study endpoints were complications, patient survival, and determination of prognostic factors. Complications were classified as major or minor. Prognostic factors were determined by analyzing multiple variables with the log-rank test., Results: Technical success rate was 100%. Primary technique effectiveness rates were 92% each at 1, 2, and 3 years. Major and minor complications occurred after 16 (25%) and 23 (35%) of the 65 sessions, respectively. The median follow-up period was 20.5 months. Overall survival rates were 87% at 1 year and 57% each at 2 and 3 years (median and mean survival times, 37.7 mo and 43.2 mo, respectively). Significantly better survival rates were obtained in cases of (i) no viable intrahepatic recurrence (P < .001), (ii) Child-Pugh class A disease (P < .001), (iii) absence of liver cirrhosis (P < .001), (iv) absence of hepatitis C virus infection (P = .006), and (v) α-fetoprotein level of 10 ng/mL or lower (P = .007) at the time of RF ablation., Conclusions: RF ablation appears effective, with an acceptable safety profile, in selected patients with pulmonary metastases resulting from HCC., (Copyright © 2011 SIR. Published by Elsevier Inc. All rights reserved.)

This report describes seven cases in which a pneumothorax was artificially created for relief from severe pain that occurred during radiofrequency (RF) ablation of peripheral lung tumors. In this procedure, the multitined probe surrounding the lesion was advanced into the chest, displacing the tines and the peripheral tumor away from the parietal pleura and the chest wall and resulting in pain relief in one patient; in the remaining patients, an intravenous catheter was also introduced, followed by the administration of carbon dioxide (CO(2)) into the space between the tumor and the parietal pleura. The pain decreased considerably immediately after this procedure. No complication related to the creation of the artificial pneumothorax was observed. Creation of an artificial pneumothorax is a safe and effective method for pain relief., (Copyright © 2011 SIR. Published by Elsevier Inc. All rights reserved.)

The present report describes four cases of brachial nerve injury caused by percutaneous radiofrequency (RF) ablation of lung cancer. All the tumors were located in the lung apex. The patients developed symptoms indicative of a low brachial plexus injury during RF ablation or as long as 7 days afterward. These symptoms partially receded over time. The indications of RF ablation in patients with apical lung cancer should be carefully determined because of the risk of brachial nerve injury associated with the procedure., (Copyright 2010 SIR. Published by Elsevier Inc. All rights reserved.)

We describe a case of pulmonary artery (PA) pseudoaneurysm related to radiofrequency ablation (RFA) of lung tumor. We performed RFA for a pulmonary epithelioid hemangioendothelioma directly adjacent to a branch of the PA. Seventeen days later, the patient complained of hemoptysis. A chest CT image revealed PA pseudoaneurysm. Transcatheter coil embolization was performed 59 days after RFA. Although PA pseudoaneurysm is rare, with an incidence of 0.2% (1/538 sessions) at our institution, it should be recognized as a risk when treating lung tumors adjacent to a branch of the PA.

Objective: : To retrospectively evaluate the effect of tumor type on local control by radiofrequency ablation in the lungs., Materials and Methods: : This study included 252 lung tumors (mean size, 13.5mm) in 105 patients (73 men and 32 women; mean age, 66.6 years) who underwent radiofrequency ablation with a multitined expandable electrode. Those tumors comprised five tumor types: primary lung cancer (n=35) and pulmonary metastases from colorectal cancer (n=117), lung cancer (n=23), renal cell carcinoma (n=49), and hepatocellular carcinoma (n=28). Local control was evaluated with contrast-enhanced computed tomography. The overall local control rates were estimated as well as those for each tumor type using the Kaplan-Meier analysis. Local control rates for a given tumor type were compared with those for the four other types. Then, multivariate multilevel analysis was performed using the variables of tumor type, tumor size, contact with a vessel or bronchus, and procedure period., Results: : The overall local control rates were 97%, 86%, 81%, and 76% at 6, 12, 18, and 24 months, respectively. Local control rates varied among the tumor types, and metastatic colorectal cancer showed significantly (P=.023) higher local control rates than those of the four other types. However, multivariate analysis indicated that the relative risk of local progression for a given tumor type was comparable to the risks for the four other types., Conclusion: : Tumor type per se did not significantly influence local control., (Copyright (c) 2010 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To determine which lung metastases are most likely to be treated effectively with a single radiofrequency (RF) application (defined as two separate applications of RF energy at a single electrode position) with a multitined expandable electrode with arrays 2 cm in diameter., Materials and Methods: The authors retrospectively evaluated 88 lung metastases (mean long-axis diameter, 0.9 cm) in 36 patients (20 men and 16 women; mean age, 57 years) treated with a single RF application with a multitined expandable electrode with arrays 2 cm in diameter. Based on follow-up computed tomographic examinations, the technique effectiveness rates were estimated with Kaplan-Meier analysis. Multiple variables were analyzed with the log-rank test to determine risk factors for local progression. Then, the technique effectiveness rates were again estimated when considering only metastases without risk factors and compared with those of other tumors., Results: The median follow-up period was 13.2 months (range, 6.0-24.7 months). Tumor size greater than 1.0 cm (P = .033) and contact with the bronchus with an inner diameter of at least 2 mm (P = .047) were the significant risk factors for local progression. The technique effectiveness rates for metastases 1.0 cm or smaller that were not in contact with the bronchus (n = 59) were 96% at 1 year and at 2 years; those rates were significantly (P = .010) higher than those in other tumors (n = 29)., Conclusions: A single RF application with a multitined expandable electrode with arrays 2 cm in diameter is most likely to suffice in small (

Objective: To evaluate the clinical utility of lung radiofrequency ablation (RFA) in patients with unresectable pulmonary metastasis from renal cell carcinoma (RCC)., Patients and Methods: We retrospectively examined 39 patients with unresectable metastases from RCC who were treated with lung RFA. Patients with six or fewer lung metastases measuring < or =6 cm that were confined in the lung, had all lung tumours ablated (curative ablation). Patients with extrapulmonary lesions, seven or more lung tumours, or large tumours of >6 cm, had mass reduction (palliative ablation). The primary endpoints was the overall survival, secondary endpoints were safety, local tumour progression rate, and recurrence-free survival in the curative ablation group., Results: There were significant differences in the overall survival rates between the curative and palliative groups at 1 year (100% vs 90%), 3 years (100% vs 52%) and 5 years (100% vs 52%) (P < 0.05). The maximum lung tumour diameter was also a significant prognostic factor. There was local tumour progression in 13 patients (33%) during the mean follow-up of 25 months. The recurrence-free survival rates were 92% at 1 year, 23% at 3 years and 23% at 5 years in the curative ablation group. Pneumothorax requiring chest tube placement (six of 89, 7%) and pneumonia (one of 89, 1%) were major complications., Conclusion: Lung RFA is a safe and effective treatment for prolonging survival in patients with unresectable RCC lung metastases.

The present study was performed to clarify the effect of hypertonic saline infusion into the lung parenchyma on radiofrequency ablation (RFA) of the lungs. A total of 20 ablation zones were created in 3 pigs. The ablation zones were divided into 3 groups. Group 1 (n=6) consisted of ablation zones created by applying smaller radiofrequency (RF) power without saline infusion; group 2 (n=5) zones were created by applying greater RF power without saline infusion;and group 3 (n=9) zones were created by applying greater RF power with saline infusion. The techniques of saline infusion included administration of hypertonic saline 1 ml before RFA, followed by continuous administration at a rate of 1 ml/min during the first 2 min after the initiation of RFA. The ablation parameters and coagulation necrosis volumes were compared among the groups. Group 3 had a tendency toward smaller mean impedance than group 1 (p=0.059) and group 2 (p=0.053). Group 3 showed significantly longer RF application time than group 2 (p=0.004) and significantly greater maximum RF power than group 1 (p=0.001) and group 2 (p=0.004). Group 3 showed significantly larger coagulation necrosis volume (mean, 1,421mm3) than group 2 (mean, 858 mm3, p=0.039) and had a tendency toward larger necrosis volume than group 1 (mean, 878 mm3, p=0.077). Although this small study had limited statistical power, hypertonic saline infusion during RFA appeared to enlarge coagulation necrosis of the lung parenchyma.

The authors describe two cases of needle-tract seeding after percutaneous radiofrequency (RF) ablation for lung cancer. Needle biopsy was performed immediately before RF ablation in one case. In both cases, RF ablation was performed with a single internally cooled electrode, which was removed without cauterizing the electrode tract. The seeding nodule appeared 4 or 7 months after RF ablation and was then completely treated with a repeat RF ablation.