Abstract

Abstract INTRODUCTION: Stereotactic radiosurgery (SRS) is an effective treatment for brain metastasis (BM), but patients remain at significant risk for distant intracranial failure (DIF) due to undetected lesions at the time of SRS or subsequent seeding. We implemented dedicated treatment planning imaging with novel MR sequences with the goals of enhancing lesion detection and consequentially increasing time to DIF, correspondingly reducing the need for whole-brain radiotherapy (WBRT). METHODS: Patients treated with SRS for BM between 05/2019-01/2024 were evaluated. MPRAGE sequences were performed for all, and 3D-FSE sequences were added starting in 02/2020. Median times to DIF and WBRT for both cohorts were estimated using the Kaplan–Meier method. RESULTS: 194 patients underwent 310 SRS courses for 1326 BM imaged with both MPRAGE and 3D-FSE (primary cohort), compared to the control cohort (88 patients, 116 SRS courses, 373 BM). MPRAGE sequences detected 1456 lesions in all 282 patients (373 in 88 control patients, 1083 in 194 primary cohort patients). In the primary cohort, an additional 204 lesions were identified with 3D-FSE (18% increase). An additional 39 lesions (3.6% increase) were identified on multidisciplinary review of both MR modalities. Although there was no statistically significant difference in median time to DIF between the cohorts (11.3 vs. 6.7 months, p=0.14), there was a trend towards longer DIF in the 1-4 metastases subgroup (14.6 vs. 7.9 months, p=0.052) and a statistically significant difference in those with a single BM (35.9 vs. 11.8 months, p=0.017). WBRT rates at 2-years were similar between the cohorts, 15% vs. 20%, p=0.2, respectively. CONCLUSIONS: A dual sequence approach at the time of SRS with multidisciplinary review improves lesion detection and lengthens time to DIF and, ultimately, next intervention. This is especially useful in confirming true BM number in those with limited intracranial disease.