Thermal ablation of lung metastases in children: what every paediatric radiologist should know.

Thermal ablation is increasingly used as a lung-sparing local treatment for selected children with pulmonary metastases, and diagnostic paediatric radiologists play a central role in lesion detection, procedural planning support, and post-treatment interpretation. This review focuses on the imaging appearance of pulmonary metastases before, during, and after percutaneous thermal ablation, highlighting the practical findings that every diagnostic radiologist should recognise. Pre-procedural imaging assessment is discussed with emphasis on lesion size, location, morphology, proximity to pleura, vessels and bronchi, and features that may affect feasibility, safety, and expected ablation margins. Intra-procedural imaging appearances are reviewed across the main techniques, including expected peri-lesional ground-glass change during heat-based ablation and ice-ball formation during cryoablation, with attention to imaging endpoints that suggest adequate target coverage and to findings that may indicate incomplete treatment or early complications. Post-ablation evolution is summarised from immediate computed tomography (CT) to short- and long-term follow-up, including expected changes in ablation zone size, density and contour, and the temporal patterns that help distinguish normal post-treatment appearances from residual viable tumour or local recurrence. Common interpretative pitfalls-such as inflammatory change, haemorrhage, atelectatic/parenchymal distortion, and pleural reaction-are addressed, together with practical reporting recommendations to improve communication within the multidisciplinary oncology team. By providing an imaging-centred framework, this article aims to support more confident and consistent interpretation of ablated lung lesions in children.