DSC-MRI With Ferumoxytol and DCE-MRI With Gadolinium in Imaging Vascular Properties in Younger Patients With Brain Tumors

Inclusion Criteria: * Participant must have either radiological (presumptive) or established (proven) histological diagnosis of a brain tumor or lesion * Previously untreated participants must have a measureable lesion on an imaging study * Participants undergoing active treatment, or who have completed treatment, will have radiographic abnormalities that may or may not be recurrent tumor * Those participants requiring surgical intervention for diagnostic and/or therapeutic purposes as necessary for their disease are eligible; the tissue may be assessed by histology and/or EM for iron particles; only clinically indicated biopsy and/or surgery will be done * Participants may have had prior therapy for the primary brain tumor, including surgery, radiotherapy or chemotherapy * After entry into the study, participants agree to be followed for up to 6 weeks after the final infusion of ferumoxytol * All participants, or their legal guardians, must sign a written informed consent and Health Insurance Portability and Accountability Act (HIPAA) authorization in accordance with institutional guidelines * Baseline MRI studies for participants receiving ferumoxytol must be performed within 16 weeks of study entry * Sexually active women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study treatment and for the duration of study treatment; should a female become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately Exclusion Criteria: * Participants with clinically significant signs of uncal herniation, such as acute pupillary enlargement, rapidly developing motor changes (over hours), or rapidly decreasing level of consciousness, are not eligible * Participants with known allergic or hypersensitivity reactions to parenteral iron, parenteral dextran, parenteral iron-dextran, or parenteral iron-polysaccharide preparations, are not eligible; participants with significant drug or other allergies or autoimmune diseases may be enrolled at the Investigator's discretion * Participants who are pregnant, lactating, or who suspect they might be pregnant are not eligible * Aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) greater than 2.5 x upper limits of normal * Glomerular filtration rate (GFR) \< 50 * Participants who have a contraindication for MRI: metal in their bodies (a cardiac pacemaker or other incompatible device), are severely agitated, or have an allergy to GBCA * Participants with known hepatic insufficiency or cirrhosis * Human immunodeficiency virus (HIV)-positive participants on combination antiretroviral therapy are ineligible * Participants that have a known or suspected iron overload (genetic hemochromatosis or history of multiple transfusions)