What is MRI?
A magnetic resonance imaging (MRI) scan is a painless procedure that lasts 15 to 90 minutes, depending on the size of the area being scanned and the number of images being taken.
Why is an MRI scan done and who needs it?
A non-invasive machine that uses magnets and computers to produce high-resolution pictures inside your body. Some common exams are the brain, bones and joints, blood vessels, internal organs, brain, and spinal cord. An MRI has NO RADIATION and you get to listen to Pandora during your exam at IIC.
BEFORE THE SCAN
On the day of your MRI scan, you should be able to eat, drink, and take any medication as usual, unless you’re advised otherwise. In some cases, you may be asked not to eat or drink anything for up to 4 hours before the scan, and sometimes you may be asked to drink a fairly large amount of water beforehand. This depends on the area being scanned.
As the MRI scanner produces strong magnetic fields, it’s important to remove any metal objects from your body. These include:
- jewelry, such as earrings and necklaces
- piercings, such as ear, nipple and nose rings
- dentures (false teeth)
- hearing aids
- wigs (some wigs contain traces of metal)
- Any valuables can usually be stored in a secure locker.
- Any implanted devices such as pacemakers, stimulators, etc are typically a “no-go”
Depending on which part of your body is being scanned, you may need to wear a hospital gown during the procedure. If you don’t need to wear a gown, you should wear clothes without metal zips, fasteners, buttons, underwire (bras), belts or buckles.
Some MRI scans involve having an injection of contrast dye. This makes certain tissues and blood vessels show up more clearly and in greater detail. You should let the staff know if you have a history of allergic reactions or any blood clotting problems before having the injection.
Sometimes the contrast dye can cause side effects, such as:
- feeling or being sick
- a skin rash
- a headache
- These side effects are usually mild and don’t last very long.
PATIENTS WITH KIDNEY DISEASE
If you have a history of kidney disease, you may be given a blood test to determine how well your kidneys are functioning and whether it’s safe to proceed with the scan. It is also possible, but extremely unlikely and rare, for contrast dye to cause tissue and organ damage in people with severe kidney disease.
An MRI scan is a painless procedure, so anesthesia (painkilling medication) isn’t usually needed. If you’re claustrophobic, you can ask for a mild sedative to help you relax. You should ask your GP or consultant well in advance of having the scan.
DURING THE SCAN
An MRI scanner is a short cylinder that’s open at both ends. IIC has a “wide bore” MRI which allows for 17% more patient space as well as “whisper MRI” technology for up to 70% less noise. You’ll lie on a motorized bed that’s moved inside the scanner. You will enter the scanner either head first or feet first, depending on the part of your body being scanned. In some cases, a frame (called a “coil”) may be placed over the body part being scanned, such as the head or chest. This frame contains receivers that pick up the signals sent out by your body during the scan and it can help to create a better-quality image.
A computer is used to operate the MRI scanner, which is located in a different room to keep it away from the magnetic field generated by the scanner. The technologist operates the computer, so they’ll also be in a separate room for you.
But you’ll be able to talk to them, usually through an intercom.
To avoid the images being blurred, it’s very important to keep the part of your body being scanned still throughout the whole of the scan until the radiographer tells you to relax.
A single scan may take from a few seconds to 3 or 4 minutes. You may be asked to hold your breath during short scans.
Depending on the size of the area being scanned and how many images are taken, the whole procedure will take 10 to 90 minutes.
The MRI scanner will make loud tapping noises at certain times during the procedure. This is the electric current in the scanner coils being turned on and off. You’ll be given earplugs or headphones to wear.
You’re usually able to listen to music through headphones during the scan if you want to.
You’ll be moved out of the scanner when your scan is over.
AFTER THE SCAN
After the scan, you can resume normal activities immediately. But if you have had a sedative, a friend or relative will need to take you home. (It’s not safe to drive, operate heavy machinery or drink alcohol for 24 hours after having a sedative.) Your MRI scan needs to be studied by a radiologist (a doctor trained in interpreting scans and X-rays) and possibly discussed with other specialists. The radiologist will send a report to the doctor who arranged the scan, who will discuss the results with you in 24-48 hours typically.