New MRI scan could reveal hidden clues about brain tumor behavior

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: Part I (Controls) Group A * Participants of all ethnic groups/race categories (≥18yrs old) * Informed consent Group B * Male participants of all ethnic groups/race categories (between the age of 18-39) * Informed consent Group C * Female participants of all ethnic groups/race categories (between the age of 18-39) * Informed consent Group D * Male participants of all ethnic groups/race categories (between the age of 40-59) * Informed consent Group E * Female participants of all ethnic groups/race categories (between the age of 40-59) * Informed consent Group F * Male participants of all ethnic groups/race categories (≥60 yrs old) * Informed consent Group G * Female participants of all ethnic groups/race categories (≥60 yrs old) * Informed consent Group H and I * Male or female participants of all ethnic groups/race categories (≥18 yrs old) * Informed consent Group J * Male or female participants of all ethnic groups/race categories (≥60 yrs old) * Informed consent * Diagnosed with mild cognitive impairment Group K * Male or female participants of all ethnic groups/race categories (≥60 yrs old) * Informed consent * Diagnosed with mild Alzheimer's disease Group L * Male or female participants of all ethnic groups/race categories (≥18 years of age) * Informed consent Group M * Male or female participants of all ethnic groups/race categories (≥18 years of age) * Informed consent Part II \& III * Adult participants of all ethnic groups/race categories (age ≥18 yrs old) * Radiographic diagnosis of brain metastases and pathological confirmation of a solid cancer primary * Metastatic brain tumor amenable to Stereotactic radiosurgery or radiotherapy * Participants on dexamethasone must be on a stable dose at the time of baseline MRI and 1-5 days post-SRS MRI * Estimated survival more than 6 months * Informed consent Exclusion Criteria: * Prior brain radiotherapy for the specific index or lesion to be imaged in the study * For groups B to I, L, and M only: Montreal Cognitive Assessment (MoCA) score \<26 * The participant will also be asked to complete the standard MRI safety screening questionnaire, prior to their research scan and participation in the study. * Contraindications to MRI including: * Participants weighing \>136 kg (weight limit for the scanner tables) * Participants with pacemakers, cerebral aneurysm clips, shrapnel injury or implantable electronic devices not compatible with MRI. * Pregnant * Claustrophobia to the extent that the participant cannot stay in the MRI for 45-60 minutes * Known adverse reactions to the contrast agent Gd-DTPA * Inability to lie still for 45-60 minutes * Participants with a high risk factor for nephrogenic systemic fibrosis (NFS). * Participant declines the procedure or further procedures; * Participant is not well enough to undergo MRI scanning; * Participant is unable to complete the MRI procedure for any reason or is non-compliant with MRI requirements. * For groups J and K, a \<1 lacunar infarct or any cortical subcortical infarct or moderate to severe white matter disease * For groups J and K, any other structural brain lesion that could affect cognition