Power Matters in CT-Guided Lung Microwave Ablation: A Multicenter Propensity-Weighted Comparison of 40 W Versus 50 W

Generator wattage is decisive yet poorly standardized for lung microwave ablation (MWA). Whether a lower-power strategy preserves long-term control while improving healing is uncertain.

To compare safety, radiographic evolution, and 12-month completeness between fixed 40-W and 50-W CT-guided lung MWA.

We conducted a harmonized, retrospective multicenter cohort across three tertiary hospitals. Consecutive adults underwent CT-guided MWA at a fixed 40 W or 50 W using a single 2.45-GHz platform with a 17-gauge internally cooled antenna and a unified protocol. A prespecified checklist set 40 W as default with selective escalation. Site-stratified, stabilized inverse-probability weights were estimated; primary models were cluster-robust by site. End points were 30-day grade ≥3 adverse events (CTCAE v5.0), serial CT evolution at approximately 48 h, 3, 6, and 12 months (early ablation-zone short-axis; cavitation or liquefaction; scar footprint), and 12-month complete ablation rate (CAR). Sensitivity analyses included weight truncation, dose-adjusted models, augmented IPW, and leave-one-site-out analyses.

Among 622 patients/sessions (40 W, n=409; 50 W, n=213), post-weighting covariate balance met targets. Grade ≥3 adverse events occurred in 5.1% after 40 W versus 17.4% after 50 W. The early ablation-zone short-axis did not differ (5.45±2.67 vs 5.67±2.36mm; p=0.41). From 3 months onward, 40 W showed steeper involution with smaller residual complexes/scars at 3, 6, and 12 months (all p<0.001) and lower cavitation rates (p≤0.005). Twelve-month CAR favored 40 W (95.6% vs 90.6%; p=0.03). Findings were consistent across subgroups; 12-month imaging follow-up was completed in 92% with similar missingness by group (p=0.78).

In a technically harmonized multicenter cohort, a 40-W strategy markedly reduced major adverse events and produced faster, cleaner radiographic healing with smaller scars while preserving-modestly improving-12-month completeness versus 50 W. These data support 40 W as the default setting for CT-guided lung MWA with selective, imaging-triggered escalation.

In a harmonized multicenter cohort (n=622), 40 W reduced 30-day grade ≥3 adverse events to 5.1% versus 17.4% with 50 W. Early coverage at ∼48 h was equivalent; thereafter, 40 W showed steeper involution, fewer cavitations, and smaller 12-month scars. Twelve-month completeness favored 40 W, consistent across subgroups and sensitivity analyses.

In a three-center, propensity-weighted cohort with central blinded imaging review and a standardized access technique, 40-W CT-guided lung microwave ablation lowered major complications and scar burden while preserving-and modestly improving-12-month local control versus 50 W, supporting 40 W as the default with selective, imaging-triggered escalation.