Definition: MRI stands for magnetic resonance imaging, which uses radio waves and a strong magnetic field to produce a detailed image of the brain. MRIs are helpful in the diagnosis of stroke, tumors, eye diseases, infections, inflammation, and damage due to head injury. MRIs can be more sensitive than CT scans in identifying certain brain pathology such as stroke and some types of tumors. MRIs can help in the diagnosis of Alzheimer's by identifying or ruling out certain causes of Alzheimer's-like symptoms. MRIs may also show focal atrophy (a decrease in brain tissue in certain parts of the brain) suggestive of Alzheimer's or other types of neurodegenerative disease.