Computed tomography-guided microwave ablation for right middle lobe pulmonary nodules: a retrospective, single-center, case-control study.

PURPOSE: This retrospective, single-center, case-control study evaluated the safety and efficacy of Computed tomography (CT)-guided microwave ablation (MWA) for pulmonary nodules located in the right middle lobe (RML), a challenging location associated with a high frequency of complications. METHODS: Between May 2020 and April 2022, 71 patients with 71 RML pulmonary nodules underwent 71 MWA sessions. To comparison, 142 patients with 142 pulmonary nodules in non-RML were selected using propensity score matching. The technical success, technique efficacy, complications, and associated factors were analyzed. The duration of the procedure and post-ablation hospital stay were also recorded. RESULTS: Technical success was achieved in 100% of all patients. There were no significant differences in technique efficacy rates between the RML and non-RML groups (97.2% vs. 95.1%, p = 0.721). However, both major (47.9% vs. 19.7%, p < 0.001) and minor (26.8% vs. 11.3%, p = 0.004) pneumothorax were more common in the RML group than non-RML group. MWA for RML pulmonary nodules was identified as an independent risk factor for pneumothorax (p < 0.001). The duration of procedures (51.7 min vs. 35.3 min, p < 0.001) and post-ablation hospital stays (4.7 days vs. 2.8 days, p < 0.001) were longer in the RML group than non-RML group. CONCLUSIONS: CT-guided MWA for RML pulmonary nodules showed comparable efficacy compared with other lobes, but posed a higher risk of pneumothorax complications, necessitating longer MWA procedure times and extended hospital stays.

Changes in the pulmonary function of CT-guided microwave ablation for patients with malignant lung tumors.

PURPOSE: To investigate the changes in pulmonary function after computed tomography (CT)-guided microwave ablation (MWA) in patients with a malignant lung tumor. MATERIALS AND METHODS: From June 2020 to January 2022, 133 patients with a malignant lung tumor who underwent CT-guided percutaneous MWA were included in the study. Pulmonary function tests (PFTs) were performed before (the baseline) and 1 month after the MWA. Vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1%, maximum mid-expiratory flow (MMEF), and diffusion capacity of the lung for carbon monoxide (DLCO-SB) at 1 month post MWA were compared with that at the baseline. The time of procedure and post-procedure length of hospital stay were also recorded. RESULTS: The mean VC, FVC, FEV1, FEV1%, MMEF, and DLCO-SB at the baseline and 1 month post MWA were 3.23 ± 0.75 and 3.22 ± 0.77 (P = 0.926), 3.20 ± 0.75 and 3.21 ± 0.77 (P = 0.702), 2.35 ± 0.70 and 2.35 ± 0.71 (P = 0.992), 91.97 ± 23.14 and 91.87 ± 23.16 (P = 0.837), 1.83 ± 0.93 and 1.81 ± 0.95 (P = 0.476), and 6.38 ± 1.67 and 6.32 ± 1.62 (P = 0.389), respectively. There was no significant difference in the PFT results before and 1 month post MWA. The mean time of procedure and post-MWA length of hospital stay were 33 min and 2.5 days, respectively. CONCLUSIONS: MWA is a lung parenchyma-sparing local treatment, and pulmonary function at 1 month post MWA was not statistically different from the baseline, indicating that MWA may not affect pulmonary function.

Lung microwave ablation: Post-procedure imaging features and evolution of pulmonary ground-glass nodule-like lung cancer.

PURPOSE: To retrospectively examine the imaging characteristics of chest-computed tomography (CT) following percutaneous microwave ablation (MWA) of the ground-glass nodule (GGN)-like lung cancer and its dynamic evolution over time. MATERIALS AND METHODS: From June 2020 to May 2021, 147 patients with 152 GGNs (51 pure GGNs and 101 mixed GGNs, mean size 15.0 ± 6.3 mm) were enrolled in this study. One hundred and forty-seven patients underwent MWA procedures. The imaging characteristics were evaluated at predetermined time intervals: immediately after the procedure, 24-48 h, 1, 3, 6, 12, and ≥18 months (47 GGNs). RESULTS: This study population included 147 patients with 152 GGNs, as indicated by the results: 43.5% (66/152) adenocarcinoma in situ, 41.4% (63/152) minimally invasive adenocarcinoma, and 15.1% (23/152) invasive adenocarcinoma. Immediate post-procedure tumor-level analysis revealed that the most common CT features were ground-glass opacities (93.4%, 142/152), hyperdensity within the nodule (90.7%, 138/152), and fried egg sign or reversed halo sign (46.7%, 71/152). Subsequently, 24-48 h post-procedure, ground-glass attenuations, hyperdensity, and the fried egg sign remained the most frequent CT findings, with incidence rates of 75.0% (114/152), 71.0% (108/152), and 54.0% (82/152), respectively. Cavitation, pleural thickening, and consolidation were less frequent findings. At 1 month after the procedure, consolidation of the ablation region was the most common imaging feature. From 3 to 12 months after the procedure, the most common imaging characteristics were consolidation, involutional parenchymal bands and pleural thickening. At ≥18 months after the procedure, imaging features of the ablation zone revealed three changes: involuting fibrosis (80.8%, 38/47), consolidation nodules (12.8%, 6/47), and disappearance (6.4%, 3/47). CONCLUSIONS: This study outlined the anticipated CT imaging characteristics of GGN-like lung cancer following MWA. Diagnostic and interventional radiologists should be familiar with the expected imaging characteristics and dynamic evolution post-MWA in order to interpret imaging changes with a reference image.