P.141 Does BRAF mutation status or being on systemic therapy alter the radiological appearance of brain metastases in metastatic melanoma?

Abstract

Background: The aim of this study is to investigate the differences in the radiological appearances of brain metastases (BM) in metastatic melanoma (MM) relative to BRAF mutation status. As well as to compare imaging differences in BM that occur prior to starting and during systemic therapy. Methods: A retrospective study was done over a 5 year period. Patients with MM with BM and known BRAF status were identified. 38 met the inclusion criteria. Imaging features on both Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) were reviewed. Results: Irrespective of BRAF mutation status, BM in MM tended to have a peripheral location with 30/38 cases having BM in the cerebral cortex. BRAF positive MM had a higher frequency of irregularly enhancing BM on CT and higher occurrence of BM showing high T1 signal on MRI. BM found during systemic treatment, regardless of BRAF status, showed less surrounding oedema, were smaller and harder to spot on CT. Conclusions: Understanding imaging features based on genetics could inform future management. The subtle features of BM on CT during systemic therapy means careful follow up with MRI may be indicated to confirm the diagnosis and to more accurately assess the burden of brain disease.