Brain metastases affect many patients with cancer.1 Given the limited intracranial penetration of most systemic therapies, the size and number of brain metastases at diagnosis determines management, with more invasive or toxic therapies such as neurosurgical resection and whole brain radiation therapy (WBRT) used for bulky and multifocal disease, respectively. Consequently, consensus guidelines from the National Comprehensive Cancer Network recommend screening magnetic resonance imaging (MRI) of the brain for patients with stage II to IV non–small cell lung cancer (NSCLC), small cell lung cancer of any stage, and stage IIIC to IV melanoma—all cancers that frequently metastasize to the brain.2