Magnetic Resonance Imaging of the Brain and Spinal Cord
Brain and spinal cord MRI uses a strong magnetic field combined with radiofrequency waves to create highly detailed, cross-sectional images of the brain and spinal cord; these scans are examined for abnormalities. For certain studies, an MRI contrast dye such as gadolinium may be injected to provide better definition of soft tissues and blood vessels and thus enhance the images.
Purpose of the Brain and Spinal Cord MRI
- To help diagnose disorders affecting the brain, including tumors; infarction (an area of dead tissue due to interruption of blood flow); edema (swelling); abscesses; and leakage of blood (hemorrhage) due to a ruptured blood vessel
- To assess various abnormalities of the spinal cord and to evaluate the spine before surgery
- To determine the extent of brain or spinal cord tumors before treatment for cancer, and to monitor the area for recurrence after therapy has been completed
- To identify multiple sclerosis and other similar disorders that cause nerve degeneration in the brain
Who Performs Brain and Spinal Cord MRI
- A radiologist or a qualified technician
Special Concerns about Brain and Spinal Cord MRI
- Because MRI can define the brain and spinal cord sharply without interference from bone, it is considered the procedure of choice to evaluate these areas (in appropriate candidates).
- People who experience claustrophobia may find it difficult to undergo an MRI, which takes place in a narrow, tunnel-like structure. In some cases, an open MRIa larger unit that is open on several sidesmay be used as an alternative.
- This test may not be possible for severely overweight individuals (over 300 lbs). Some open MRIs can accommodate larger patients.
- Because the MRI generates a strong magnetic field, it cannot be performed on people who have certain types of internally placed metallic devices, including pacemakers, inner ear implants, or intracranial aneurysm clips.
- The test should not be done in pregnant women because the long-term effects of MRI on the fetus are unknown.
Before the Brain and Spinal Cord MRI
- Tell your doctor if you suffer from claustrophobia. He or she may administer a sedative to help you tolerate the procedure.
- You will be asked to fast 8 to 12 hours before the test.
- Empty your bladder before the test.
- Remove any magnetic cards or metallic objects, including watches, hair clips, belts, credit cards, jewelry and body piercing.
- Remove pens, pocketknives and eyeglasses, hearing aids, all of which can be damaged. You may be asked to disrobe and put on a hospital gown.
What You Experience during Brain and Spinal Cord MRI
- You will lie down on a narrow padded bed that slides into the large, enclosed cylinder containing the MRI magnets.
- You must remain still throughout the procedure because any motion can distort the scan. Your head will likely be placed in a cradle to restrict movement.
- In some cases, you will receive an injection of a contrast dye before or during the procedure.
- There is a microphone inside the imaging machine, and you may talk to the technician performing the scan at any time during the procedure.
- You will hear loud thumping sounds as the scanning is performed. To block out the noise, you can request earplugs or listen to music on earphones.
- The procedure can take up to 90 minutes, or longer if a contrast dye is used.
Risks and Complications of Brain and Spinal Cord MRI
- MRI does not involve exposure to ionizing radiation and is not associated with any risks or complications.
- If sedation is used during the procedure, excessive sedation may occur. Vital signs are monitored by the technologist or nurse to reduce this risk.
- Any implanted medical devices that contain metal may cause problems or malfunction due to the strong magnetic field during an MRI exam.
- If contrast material is injected, there is a very slight risk of an allergic reaction, which is usually mild and easily controlled. If you experience allergic reaction, a radiologist or other physician will provide immediate assistance.
After the Brain and Spinal Cord MRI
- Most patients can go home right after the scan and resume their usual activities.
- Sedated patients may be monitored for a short period until the effects of the sedative have worn off.
- If contrast dye was injected, blood may collect and clot under the skin (hematoma) at the injection site; this is harmless and will resolve on its own. For a large hematoma that causes swelling and discomfort, apply ice initially; after 24 hours, use warm, moist compresses to help dissolve the clotted blood.
Results of Brain and Spinal Cord MRI
- The MRI scans are displayed on a video monitor and then recorded on film. A physician will examine the images for any abnormalities.
- If a definitive diagnosis can be made based on the images, appropriate treatment will be initiated, depending on the specific problem.
- In some cases, additional tests, such as arteriography of the brain or lumbar puncture, may be needed to establish a diagnosis and determine the extent of the problem.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media