How to Understand MRI Scans
Magnetic resonance imaging (MRI) uses magnetic fields rather than X-rays to create three-dimensional images of the interior of your body. The magnetic fields produced by the scanner cause atoms (protons) to line up and create signals that transmit to a computer and convert to images. The MRI can take multiple pictures (slices) at any angle and can precisely identify abnormalities in soft tissue, such as tumors. The MRI has large, powerful magnets that surround you as well as low-strength "gradient" magnets that cause the noise you hear during your scan.
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Things You'll Need
- Loose, comfortable clothes CD of favorite music (if earphones available) Earplugs
Instructions
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The MRI Scan
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Wear warm clothing because the MRI equipment must be kept cool, so the room will be chilly, and wear loose, comfortable clothing because you will need to stay still for long periods, usually 15 to 60 minutes. A T-shirt and sweatpants are ideal. You must remove all metal, such as jewelry, and clothes with metal fasteners (including your bra).
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Lie down on the examining table, which slides into the bore (center) of the MRI machine. Imaging coils that help to produce images are usually placed about the part of your body that is the focus of the scan. For example, if you are having a brain scan, your head will fit into a special "bird-cage" frame, which also helps to keep the body part immobilized.
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Adjust headphones (if available) or insert earplugs before you slide into the bore because you can't move once the scan begins. You will experience periods of quiet interspersed with periods of very loud clicks, beeps and buzzes often accompanied by movement of the table or vibrations.
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Avoid moving if the scanning stops so you can receive intravenous contrast (gadolinium). The scan will resume when the technician finishes administering the contrast, which alters the magnetic fields to produce better images. In some cases, you must drink contrast material.
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Breathe and try to relax during the scan. Most MRI scanners are about 6 feet long, but a few have short bores and take scans of part of the body. Sitting/standing open MRI scanners allow weight-bearing during the scan. The inside of the bore is lighted, and you can feel air flowing past you.
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Tips & Warnings
If you have diabetes or history of liver or kidney disease or are older than 60 to 65 and will receive gadolinium contrast, you need a creatinine (kidney function) test before your MRI.
The kidneys must excrete gadolinium contrast, which is a paramagnetic metal ion, so the contrast is contraindicated with kidney disease. You cannot have an MRI if you have a pacemaker, a cochlear implant, aneurysm clips, some types of dental implants or metal fragments in your body because the powerful magnetic field will cause them to move. You must wait at least six weeks after receiving a metal prosthesis (such as a hip joint) to ensure it is firmly in place.
References
Resources
- Photo Credit BrokenSphere at Wikimedia Commons CC 3.0
