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Magnetic resonance imaging (MRI) uses a large magnet, radiofrequencies, and a computer to produce detailed images of organs and structures within the body, in this case, the brain and spine. MRI is used to help diagnose a health problem.
The MRI machine is a large, tube-shaped machine that creates a strong magnetic field around the patient. Some look like narrow tunnels. Others are more open. This magnetic field, along with a radiofrequency, alters the hydrogen atoms' natural alignment in the body. Computers are then used to form two-dimensional (2D) images of the brain and/or spine based on the activity of the hydrogen atoms. Cross-sectional views can be done to show more details. MRI does not use radiation, like X-rays or computed tomography (CT scans).
Magnetic resonance (MRI) may be used instead of computed tomography (CT) when organs or soft tissue are being studied. This is because with MRI scanning bones do not obscure the images of organs and soft tissues, as does CT scanning.
Functional magnetic resonance imaging of the brain (fMRI) is used to determine the specific location of the brain where a certain function, such as speech or memory, occurs. The general areas of the brain in which such functions occur are known, but the exact location may vary from person to person. During fMRI imaging of the brain, you will be asked to do a specific task, such as recite the Pledge of Allegiance, while the scan is being done. By pinpointing the exact location of the functional center in the brain, doctors can plan surgery or other treatments for certain brain disorders.
MRI may be used to check the brain and/or spinal cord for injuries, the presence of structural abnormalities, or certain other conditions, such as:
MRI can also help to identify the specific part of the brain controlling a function, such as speech or memory, to assist in treatment of a condition of the brain.
There may be other reasons for your doctor to recommend MRI of the spine or brain.
There is no risk of exposure to radiation during an MRI procedure.
Due to the use of the strong magnet, MRI cannot be used for people with the following:
If you are pregnant or think you may be, tell your doctor. In general, there is no known risk of MRI in pregnancy. However, particularly in the first trimester, MRI should only be used to address very important problems or suspected abnormalities.
If contrast dye is used, there is a risk for allergic reaction to the dye. If you are allergic to or sensitive to medications, contrast dye, or iodine, tell your doctors.
MRI contrast may have an effect on other conditions such as allergies, asthma, anemia, low blood pressure, kidney disease, and sickle cell disease.
Nephrogenic systemic fibrosis (NSF) is a very rare but serious complication of MRI contrast use in people with kidney disease or kidney failure. If you have a history of kidney disease, kidney failure, kidney transplant, liver disease, or are on dialysis, be sure to tell the MRI technologist or radiologist before getting the contrast dye.
There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor before the procedure.
Your doctor will explain the procedure to you and give you a chance to ask questions.
If your procedure involves the use of contrast dye, you will be asked to sign a consent form that gives permission to do the procedure. Read the form carefully and ask questions if anything is not clear.
Generally, there is no special restriction on diet or activity prior to an MRI procedure.
Before the MRI, it is extremely important that you inform the technologist if any of the following apply to you:
There is a possibility that you may get a sedative before the procedure, so you should plan to have someone drive you home afterward.
Based on your medical condition, your doctor may request other specific preparation.
MRI may be done on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your doctor’s practices.
Generally, MRI of the spine and brain follows this process:
While the MRI itself causes no pain, having to lie still for the length of the procedure might cause some discomfort or pain, particularly if you’ve recently been injured or had surgery. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain.
On occasion, some people with metal fillings in their teeth may experience some slight tingling of the teeth during the procedure.
Move slowly when getting up from the scanner table to avoid any dizziness or lightheadedness from lying flat for the length of the procedure.
If any sedatives were used for the procedure, you may need to rest until the sedatives have worn off. You will also need someone to drive you home.
If contrast dye is used, you may be monitored for a period for any side effects or reactions to the contrast dye, such as itching, swelling, rash, or difficulty breathing.
If you notice any pain, redness, and/or swelling at the IV site after you go home, tell your doctor as this could be a sign of infection or other type of reaction.
Otherwise, there is no special type of care required after a MRI scan of the spine and brain. You may go back to your usual diet and activities, unless your doctor tells you differently.
Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.
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