ESTRO 2025 - Abstract Book

S648

Clinical - CNS

ESTRO 2025

unknown. This study evaluates the impact of incorporating 3D-TSE to MPRAGE on brain metastasis (BM) detection and time to distant intracranial failure (DIF) in patients with prior WBRT compared to those who are WBRT-naïve.

Material/Methods: We evaluated outcomes in BM patients with prior WBRT (primary cohort), who underwent either MPRAGE alone or a dual sequence of MPRAGE and 3D-TSE, and compared them to a control cohort of WBRT-naïve patients. All patients were treated with SRS for BM between January 2019 and February 2024. Median times to DIF were estimated using the Kaplan-Meier method with group comparisons made using Chi-square/Mann-Whitney U tests. Results: The primary cohort of 39 patients underwent 75 SRS sessions for 662 BM consisting of 42 SRS sessions to 417 BM imaged with the dual sequences and 33 sessions to 245 BM with MPRAGE alone. In the control cohort, 467 SRS sessions were performed in 308 WBRT-naïve patients, either treated with dual sequence approach (332 SRS sessions for 1456 BM) or MPRAGE alone (135 SRS sessions for 462 BM). The median number of treated BM per session (5, Range: 1-28 vs. 2, Range: 1-31, p<0.05) and frequency of widespread extracranial disease (70.7% vs. 52.7%, p<0.05) were significantly higher in the primary cohort. The dual sequence approach significantly prolonged time to DIF in the control cohort (11.4 vs. 6.8 months, p=0.03) but showed no statistically significant benefit in the primary cohort (6.5 vs. 5.6 months, p=0.76). When only the dual sequence groups were compared, 285 out of 1456 (19.6%) lesions were detected by 3D-TSE in the control cohort, whereas 3D-TSE detected only 12.0% of lesions (50/417) in primary cohort, p<0.001. Conclusion: Adding 3D-TSE to MPRAGE improves BM detection and prolongs time to DIF in WBRT-naïve patients and should be included into routine treatment planning. Dual imaging shows no benefit in patients with a history of prior WBRT, therefore judicious use in this patient population is warranted. The diminished benefit of 3D-TSE in previously irradiated patients is potentially driven by the disrupted blood-brain barrier, which may enhance MPRAGE imaging through increased contrast penetration, and the higher burden of extracranial disease in this group, which facilitates rapid tumor re-seeding and potentially limits the advantages of detecting subtle BMs with 3D-TSE. Digital Poster Multidisciplinary management of 121 Spinal Ependymomas-single institutional experience from a specialized neuro-oncology practice in India Abhishek Chatterjee 1 , Prachi Sawant 1 , Archya Dasgupta 1 , Jayshree Jansari 1 , Zeba Tarannum 1 , Epari Sridhar 2 , Ayushi Sahay 2 , Aekta Shah 2 , Arpita Sahu 3 , Kajari Bhattacharya 3 , Amit Choudhari 3 , Amrita Guha 3 , Vikas Singh 4 , Prakash Shetty 4 , Aliasgar Moiyadi 4 , Tejpal Gupta 4 1 Radiation Oncology, Tata Memorial Center, Mumbai, India. 2 Pathology, Tata Memorial Center, Mumbai, India. 3 Radiology, Tata Memorial Center, Mumbai, India. 4 Neurosurgery, Tata Memorial Center, Mumbai, India Purpose/Objective: Spinal Ependymomas are uncommon tumors underpinned by diverse biology and clinical behavior and merit careful multidisciplinary care to achieve optimal outcomes with manageable morbidity. Maximal safe resection followed by tailored adjuvant Radiotherapy (RT)for residual tumor and/or high-grade histology in the newly diagnosed setting or for progressive disease in the recurrent /relapsed setting forms the cornerstone of management. Outcomes of 121 spinal ependymomas treated between 2008-2020 are presented herein under the following categories1.Myxopapillary Ependymoma (MPE)2. High-Grade Ependymoma (HGE) 3. Other ependymomas (OE Classified variously histologically as ependymoma, cellular ependymoma or ependymoma NOS/EPEN NOS). Keywords: 3D turbo spin echo (3D-TSE), brain metastases, SRS 331