NIMG-05. ARTIFICIAL INTELLIGENCE-BASED RESPONSE ASSESSMENT FOR PATIENTS RECEIVING LASER INTERSTITIAL THERMAL THERAPY

Abstract BACKGROUND Laser interstitial thermal therapy (LITT) is a minimally invasive option for tissue diagnosis, cytoreduction, and rapid post-operative return to systemic therapies for patients with brain tumors or radiation necrosis. As ablated tissue remains in situ, post-LITT edema may be associated with apparent increased lesion size and transient clinical worsening, complicating assessment of progression. METHODS All patients receiving LITT at a single center for tumors or radiation necrosis from 2015 – 2023 with ≥ 9 months of MRI follow-up were retrospectively reviewed. A 3D U-net segmentation model implemented in nnU-Net was developed for automated segmentation of Contrast-enhancing Lesion Volume (CeLV) of LITT-treated lesions on T1-weighted post-contrast MR images. CeLVs were analyzed to establish volumetric post-LITT response assessments. RESULTS Across 384 unique MRI exams, 61LITT-treated lesions and 6 control cases of medically-managed radiation necrosis were analyzed. Automated segmentation was qualitatively accurate in 367/384 (95.6%) images. CeLV increased to a median of 68.3% (IQR 35.1 – 109.2%) from baseline at 1 – 3 months from LITT (P = 0.0012) and returned to baseline thereafter. Based on established criteria, volumetric disease progression was defined as lesion expansion 40% from volumetric nadir or baseline. Twenty-one of 56 (37.5%) patients experienced volumetric progression with a progression-free survival of 21.4 (6.0 – 93.4) months. Patients experiencing volumetric progression had lower mOS (17.3 vs 62.1 months, P = 0.0015). CONCLUSIONS We observed a stereotyped increase in CeLV at 1 – 3 months post-LITT, which resolved within 6 months of the procedure. Post-LITT disease response can be reliably and feasibly assessed with criteria that account for this transient CeLV expansion. Automated lesion segmentation may speed adoption of volumetric response assessment criteria to clinical practice.