MRI (Head)

Magnetic resonance imaging (MRI) is a painless, safe, and radiation-free test. MRI uses a large magnetic field, pulses of radio waves, and a computer to produce detailed, cross-sectional images of internal organs and blood vessels.

MRI is used to diagnose the following conditions:

Aneurysms;
Brain tumors;
Stroke; and
Traumatic brain injuries.

PRE-TEST GUIDELINES

Typically, there is no preparation for an MRI.

RISK FACTORS

Patients who may be unsuited for MRI include:

People with implanted metal devices;
Those who suffer from claustrophobia;
Pregnant women; and
Patients with pacemakers or defibrillators.

WHAT TO EXPECT

An MRI is usually administered in a hospital or an outpatient healthcare facility and takes 30 to 90 minutes.

The patient changes into a hospital gown, removes any metal items, and lies on the MRI table. A helmet-like device, called a surface coil, may be placed around the head. Because MRI images can become blurred with motion, the technician may offer the patient a sedative. In some centers, a contrast liquid is injected into the veins to improve the images.

The MRI table slides through a hollow, donut-shaped machine called a gantry that houses the MRI scanner. The scanner creates a magnetic field and directs radio waves at the area being scanned. This exposure is painless but may cause some patients to feel a mild tingling in any dental fillings. Throughout the procedure, the scanner produces humming and thumping sounds.

The only discomfort associated with the test is stiffness in the back caused by having to lie still on a hard surface for an extended period.

POST-TEST GUIDELINES

If patients are given contrast dye as part of the test, they will be asked to drink liquids to flush the dye from their system. If patients receive a sedative, they will need to arrange a ride home. Otherwise, patients can resume normal activities immediately.

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