Association between Three-dimensional Margin Assessment and Local Tumor Control in Percutaneous Lung Cryoablation of Colorectal Metastases.

Purpose To evaluate the association of two minimum ablation margin (MAM) estimation methods: manual three-dimensional segmentation and biomechanical deformable image registration (DIR) with local tumor progression-free survival (LTPFS) after percutaneous lung cryoablation of colorectal pulmonary metastases. Materials and Methods This retrospective single-institution study included patients who underwent percutaneous lung cryoablation between May 2012 and March 2023 (median follow-up, 3.6 years; range, 0.8-9.6 years). Manual three-dimensional MAM was calculated for all tumors, and DIR-based MAM was estimated in a subset with intraprocedural full-thorax imaging. Cox proportional hazards regression assessed associations between MAM and LTPFS. The primary outcome was 2-year LTPFS, with a secondary outcome of whether DIR-based MAM was associated with LTPFS. Results Thirty-eight patients (76 colorectal pulmonary metastases in 63 procedures; mean age, 58 years ± 12 [SD]; 19 female patients) were included. Technical success was 100% (63 of 63). Per-lesion LTPFS at 1 and 2 years was 87% and 84%. Five tumors (6.6%; five of 76) had no margin (0 mm), 55 tumors (72%; 55 of 76) had a MAM 0-5 mm, and 16 (21%; 16 of 76) had an MAM greater than 5 mm. Median LTPFS was 6 months for the 0-mm group and was not reached for the MAM 0-5-mm and the greater than 5-mm groups ( < .001). Receiver operating characteristic analysis for 2-year local progression yielded an area under the receiver operating characteristic curve (AUC) of 0.81 (95% CI: 0.62, 0.95). Among 36 tumors (22 patients) with full-lung imaging available, the DIR-based MAM had an AUC of 0.76 (95% CI: 0.55, 0.98), and the manual method had an AUC of 0.79 (95% CI: 0.52, 1.00). At multivariable analysis, MAM greater than 0-5 mm (hazard ratio [HR], 0.05; < .001), MAM greater than 5 mm (hazard ratio, 0.03; = .005), and ablation volume (hazard ratio, 0.93; < .001) were independently associated with reduced LTP. Conclusion Quantitative MAMs are strongly associated with LTPFS, underscoring the importance of achieving adequate margins in percutaneous lung cryoablation. Pulmonary Cryoablation, Deformable Image Registration, Colorectal Cancer, Pulmonary Metastasis, Minimum Ablation Margin © RSNA, 2026.