- Exception: Adequately treated brain metastases documented by baseline computed tomography (CT) or magnetic resonance imaging (MRI) scan that have not progressed since previous scans and do not require corticosteroids (except prednisone ≤ 5 mg/day or equivalent) for management of CNS symptoms. A repeated CT or MRI following the identification of CNS metastases (obtained at least 2 weeks after definitive therapy) must document adequately treated brain metastases