The devastating consequence of a brain tumor on a patient’s quality of life and survival has sparked a widespread search for novel therapeutic approaches (e.g. antiangiogenic therapies) to arrest cancer progression. This in turn has galvanized the development of new biomarkers capable of assessing the efficacy of such drugs in vivo. This lecture will provide an overview of how, why and which MRI-derived biomarkers are ideally suited for assessing the angiogenic status of brain tumors, noninvasively and safely in patients. Specifically, this lecture will introduce core concepts about the blood vessels of brain tumors, their role in disease progression, and how one can image them with certain MRI contrast mechanisms, in the preclinical and clinical setting.