We apply a new triaxial antenna for microwave ablation procedures to an ex vivo bovine liver. The antenna consists of a coaxial monopole inserted through a biopsy needle positioned one quarter-wavelength from the antenna base. The insertion needle creates a triaxial structure, which enhances return loss more than 10 dB, maximizing energy transfer to the tissue while minimizing feed cable heating and invasiveness. Numerical electromagnetic and thermal simulations are used to optimize the antenna design and predict heating patterns. Numerical and ex vivo experimental results show that the lesion size depends strongly on ablation time and average input power, but not on peak power. Pulsing algorithms are also explored. We were able to measure a 3.8-cm lesion using 50 W for 7 min, which we believe to be the largest lesion reported thus far using a 17-gauge insertion needle.

Purpose: To prospectively evaluate, in vivo in pigs, an impedance-based multiple-electrode radiofrequency (RF) ablation system for creation of confluent areas of hepatic coagulation. Materials and ...

Stereotactic body radiation therapy (SBRT) is the standard of care for inoperable early stage non-small cell lung cancer (NSCLC). Use of image guided thermal ablation (IGTA; including microwave ablation [MWA] and radiofrequency ablation [RFA]) has increased in NSCLC, however there are no studies comparing all three. To compare the efficacy of IGTA (including MWA and RFA) and SBRT for the treatment of NSCLC. Published literature databases were systematically searched for studies assessing MWA, RFA, or SBRT. Local tumor progression (LTP), disease-free survival (DFS), and overall survival (OS) were assessed with single-arm pooled analyses and meta-regressions in NSCLC patients and a stage IA subgroup. Study quality was assessed with a modified methodological index for non-randomized studies (MINORS) tool. Forty IGTA study-arms (2,691 patients) and 215 SBRT study-arms (54,789 patients) were identified. LTP was lowest after SBRT at one and two years in single-arm pooled analyses (4% and 9% vs. 11% and 18%) and at one year in meta-regressions when compared to IGTA (OR = 0.2, 95%CI = 0.07-0.63). MWA patients had the highest DFS of all treatments in single-arm pooled analyses. In meta-regressions at two and three-years, DFS was significantly lower for RFA compared to MWA (OR = 0.26, 95%CI = 0.12-0.58; OR = 0.33, 95%CI = 0.16-0.66, respectively). OS was similar across modalities, timepoints, and analyses. Older age, male patients, larger tumors, retrospective studies, and non-Asian study region were also predictors of worse clinical outcomes. In high-quality studies (MINORS score ≥ 7), MWA patients had better clinical outcomes than the overall analysis. Stage IA MWA patients had lower LTP, higher OS, and generally lower DFS, compared to the main analysis of all NSCLC patients. NSCLC patients had comparable outcomes after SBRT and MWA, which were better than those with RFA.

Background: Image-guided percutaneous thermal ablation is an established treatment option for early-stage lung cancer in medically inoperable patients but carries a high risk of pleura-related complications, particularly pneumothorax. Objective: This study aimed to determine if image-guided transbronchial microwave ablation (tMWA) is a feasible approach to treat peripheral stage 1 lung cancer. Method: A prospective, single-arm, multicenter study sought to enroll 40 adults who were medically inoperable or declined surgery for peripheral stage 1 lung tumors (≤20 mm). Ablation was performed using navigational bronchoscopy and a flexible MWA probe, guided by cone-beam CT with augmented fluoroscopy. Follow-up at 1, 6, and 12 months included CT imaging of the ablation zone and possible tumor recurrence, adverse events (AEs), pulmonary function, and quality of life. Results: Across 2 sites, 11 tumors (10 NSCLC, 1 carcinoid) were treated in 10 enrolled patients. Median tumor diameter was 13 × 14 mm (7–19 mm) and median minimum ablative margin was 11 mm (5–19 mm). Technical success and technique efficacy were achieved in all patients. No tumor recurrence was seen during 12-month follow-up. No pneumothorax, pleural effusion, or bronchopleural fistula were noted. Minor AEs included scant hemoptysis, pain, cough, and dyspnea. Two serious AEs occurred ≤30 days of ablation and included a COPD exacerbation (day 9) and a death of unknown cause (day 15). The death led the sponsor to halt enrollment. Pulmonary function and quality-of-life indices remained stable. Conclusions: Image-guided tMWA is a technically feasible approach for peripheral early-stage lung cancer but warrants further evaluation of safety and efficacy in larger cohorts.