Reasons for a Brain MRI

A magnetic resonance imaging scan, or MRI, allows doctors to examine the brain without opening the skull. The National Institutes of Health explains that an MRI produces a magnetic field that is 10,000 times greater than the one produced by the earth. Doctors can use an MRI to diagnose multiple disorders that cause physiological changes to the brain.

Degenerative Diseases

An MRI can detect a disorder that causes destruction of the brain tissue. For example, a doctor may use an MRI to diagnose multiple sclerosis, a disorder that affects the nerves. Multiple sclerosis results from destruction of the myelin sheath, called demyelination. The myelin sheath surrounds the neurons and appears as the white part of the brain. An MRI can show the reduction of myelin sheath in the brain. The Mayo Clinic’s adds that an MRI can also show the progression of dementia, a neurological condition in which patients lose cognitive functions. The MRI can show the loss of brain tissue as the disease progresses into the later stages.


A doctor may do an MRI on a patient with bleeding in the brain. The National Institutes of Health notes that reasons for a brain MRI include subarachnoid hemorrhages and intracranial hemorrhages. With an intracranial hemorrhage, the bleeding occurs within the brain. With a subarachnoid hemorrhage, the bleeding occurs in the subarachnoid space, an area in between the brain and the outer covering of the brain. An MRI can also detect a stroke and an aneurysm, according to the Mayo Clinic. A burst blood vessel or a blocked blood vessel can cause a stroke, preventing the blood from reaching parts of the brain. An abnormal widening of a blood vessel, or aneurysm, can cause bleeding in the brain when it ruptures.


An MRI is part of the diagnostic process of a brain tumor. The National Institutes of Health explains that a doctor will use an MRI to determine the difference between normal tissue and tumor tissue. An MRI can also show the location of the brain tumor and its size. But a doctor needs a biopsy, which takes some of the tumor tissue, to figure out if the tumor is benign or cancerous.


Another reason for a brain MRI is to detect an infection, such as encephalitis, which causes inflammation in the brain. For example, an MRI can show if brain swelling or damage to the brain tissue has occurred. The Merck Manual Professional Edition notes that an MRI can indicate demyelination, which can be caused by progressive multifocal leukoencephalopathy, a type of infection.

Hormonal Disorders

Patients with a hormonal disorder, such as Cushing’s syndrome, galactorrhea and acromegaly, may undergo an MRI. These hormonal disorders result from abnormal functioning of the pituitary gland, which controls hormone levels. The National Endocrine and Metabolic Diseases Information Service, a service of the National Institute of Diabetes and Digestive and Kidney Diseases, explains that the MRI detects size and location of the tumor caused by the excessive hormones.

Abnormal Development

The National Institutes of Health notes that a doctor may use a brain MRI to detect abnormal brain development. The abnormalities in the brain may result from prenatal exposure to toxins or drugs or from an injury during or right after birth, such as cerebral palsy.

About this Author

Lia Stannard has her Bachelor of Science degree in neuroscience with an emphasis on neuropsychology. She is a certified sexual assault crisis counselor. She has presented her research in memory at several national conferences. Stannard has been a freelance writer for more than five years, covering women\’s health, politics and medicine.