You don’t feel the magnetic field or radio waves, and there are no moving parts around you.
During the MRI scan, the internal part of the magnet produces repetitive tapping, thumping sounds and other noises. Earplugs or music may be provided to help block the noise. If you are worried about feeling claustrophobic inside the MRI machine, talk to your doctor beforehand. He or she may make arrangements for you to receive a sedative before the scan.
An MRI typically lasts about an hour. You must hold very still because movement can blur the resulting images. In some cases, contrast agents are injected into your veins to enhance the appearance of certain tissues or blood vessels in the images.
During a functional MRI, you may be asked to perform a number of small tasks — such as tapping your thumb against your fingers, rubbing a block of sandpaper or answering simple questions. This helps pinpoint the portions of your brain that control these actions.
After the test:
If you haven’t been sedated, you may resume your usual activities immediately after the scan. Nursing mothers shouldn’t breast-feed for 36 to 48 hours after an MRI if a contrast material was used. Very rarely, the contrast material can cause hives and itching.
A radiologist — a doctor specially trained to interpret MRIs — will analyze the images from your scan and report the findings to your doctor. Your doctor will then discuss any important findings and next steps with you.
It can be difficult if you are uneasy in tight spaces or have trouble lying flat for that amount of time. If you think you might have trouble getting through the procedure, talk to your doctor beforehand and discuss whether an anti-anxiety medicine might help. After the test is done, you can go about your normal activities.
How long is it before the result of the test is known?
MRI images are often recorded on film; if so, it will take at least an hour for the MRI department to develop the images and additional time for a doctor to examine and interpret them. If the images are stored in and displayed by a computer, there is no time required to develop the images, although the doctor’s interpretation still takes time. You can probably get preliminary results within a day or two, but the complete results might take four to seven days.