139 Double-dose gadolinium SRS planning MRI reduces repeat treatment for brain metastases

Abstract Introduction Double‑dose gadolinium contrast for stereotactic radiosurgery (SRS) planning MRI can increase detection of brain metastases, but its clinical benefit remains uncertain. One hypothesised advantage is reduced need for repeat SRS by treating small lesions earlier. We compared outcomes in patients planned with double‑dose versus single‑dose gadolinium contrast. Method Patients undergoing double‑dose gadolinium SRS planning MRI for brain metastases between January 2024–January 2025 were identified and matched by primary tumour and initial brain metastasis number to patients treated before implementation of double‑dose contrast (January 2022–January 2023). Outcomes included repeat SRS, time to repeat SRS, new metastases on follow‑up imaging, salvage intracranial therapy other than SRS, nephrogenic systemic fibrosis (NSF) and overall survival. Results Data were available for 62 patients in each group. Median follow‑up was 21 months (range 3–38). The crude repeat SRS rate was 22.5% with double‑dose and 32.2% with single‑dose gadolinium, corresponding to an approximate 30% relative risk reduction and a number needed to treat of 11 to prevent one repeat SRS. Time to repeat SRS, number of new metastases, use of salvage intracranial therapy and overall survival did not differ significantly between groups. No cases of NSF were observed. Conclusions Double‑dose gadolinium SRS planning MRI was associated with a clinically meaningful reduction in the proportion of patients requiring repeat SRS, without detectable differences in overall survival or safety. Further prospective evaluation is warranted.