Robot-assisted CT-guided cryoablation of pulmonary metastases: an IDEAL stage 2a prospective development study

To evaluate the feasibility, safety, and technical performance of robot-assisted CT-guided cryoablation for pulmonary metastases.

A single-centre IDEAL stage 2a prospective development study of 26 participants (median age 62 years, IQR 47-71; 14 men) who underwent 30 procedures targeting 37 lung metastases using a robotic navigation system. Median tumour diameter was 9.8 mm (IQR 5.1-12.8). All procedures were performed under general anaesthesia with high-frequency jet ventilation. Feasibility, safety, and technical performance (targeting accuracy, manipulations, radiation dose) were recorded.

Robotic guidance was successfully completed without conversion in 35/37 tumours (95%). One major complication occurred (3%, CTCAE grade 3 pneumothorax requiring 4 days of drainage); all others were grade 1-2. Pneumothoraces were managed by observation (n = 7) or prophylactic intraprocedural chest drain insertion (n = 11). No bronchopleural fistulas were observed. Median hospital stay was 1 night (IQR 1-2). A total of 54 cryoprobes were used. Median Euclidean targeting error on first insertion was 6.1 mm (IQR 2.9-9.7) and lateral error 4.2 mm (IQR 2.2-6.5). The median number of manipulations per probe was 1 (IQR 0-2.5), with one-third requiring no adjustment. Once integrated into the workflow, the "chopstick" technique was frequently applied, supporting conformal ablation. Median total procedure time was 66.5 min (IQR 56.6-92.8). Twelve-month local tumour progression-free survival was 97%.

Robot-assisted CT-guided cryoablation of pulmonary metastases was feasible, safe, and accurate, achieving high targeting precision with minimal cryoprobe manipulation. These findings support evaluation in prospective comparative trials.

Question Robotic-assisted CT-guided cryoablation of lung metastases is feasible and safe, achieving high targeting accuracy and minimal probe manipulation, even in anatomically challenging cases. Findings Robotic trajectory planning supported complex multiprobe configurations. Procedural refinements-including patient positioning, probe selection, and adoption of "chopstick" configurations-were introduced to address bleeding risk and optimise energy delivery. Clinical relevance Robot-assisted navigation is particularly advantageous in cryoablation, enabling minimal manipulations and accurate probe placement despite the often-necessary complex trajectories.