Imaging-based techniques for ablation zone definition and volumetry after laser interstitial thermal therapy (LITT) for intracranial lesions: a systematic review.

Abstract

MRI-guided laser interstitial thermal therapy (LITT) is a minimally invasive technique for treating intracranial pathologies. Although the extent of ablation appears prognostically relevant, standardized imaging methods for post-LITT ablation zone measurements are lacking. This systematic review evaluates imaging-based approaches used to measure the ablation zone in patients undergoing LITT. As effect assessment is an integral part of the technique, this study aims to support the development of standardized imaging-based outcome metrics. A systematic literature search was conducted in PubMed and Embase (March 15, 2024; updated April 2, 2025). Studies were included if they reported imaging-based methods for determining ablation extent or volume after LITT; studies without methodological detail, non-original research, or non-human studies were excluded. Study selection, data extraction, and risk of bias assessment (Newcastle-Ottawa Scale) were conducted independently by multiple reviewers. A total of 77 studies (2,312 patients) were included. Most studies (82%) were retrospective case series, with 74 (96%) categorized as having moderate risk of bias. All studies utilized MRI to assess post-LITT ablation volume. Conventional MRI sequences were used in 65 studies (84%), among which 54 (83%) used contrast-enhanced imaging. Forty-six studies (60%) reported a single time-point volume assessment. Of the 60 studies using contrast-enhanced imaging, 50% specified inclusion or exclusion of the enhancing rim. Our results show considerable variation and underreporting regarding rim inclusion, measurement timing, and volume definitions. Standardized imaging protocols, covering timing, modalities, and rim handling, are essential to improve LITT research and outcomes. We propose four recommendations to guide future reporting of imaging methods. Not applicable.