What is MRI?
Magnetic Resonance Imaging (MRI) is a technique that produces detailed images of the inside of your body. These images produce a clear picture of your internal organs and soft tissues, from many different angles. Dozens of images may be produced during any one scan, depending on your doctor’s request.
MRI works by using radio waves (similar to those emitted by your TV antenna) and magnetic fields, in conjunction with special computers. The magnetic field that is produced prepares the cells of your body to reflect radio ‘signals’. The signals reflected by any abnormal cells are identifiable on the image or ‘picture’ that is produced. MRI is, therefore, an important and very useful tool in the location and diagnosis of abnormalities of the brain, spine, joints and internal organs.
Is MRI Safe?
The radio and magnetic waves used during MRI are in themselves safe and no adverse health or side effects have been reported following normal exposures. There is no radiation or x-ray involved in the procedure. However, if you have :
- A pacemaker
- Metallic implants or other sources of metal within your body.
- Internal contraceptives
- A prosthetic device
- Heart problems
you need to inform your neurologist prior to the examination as the procedure may not be suitable for you. There has been no evidence to suggest that MRI is hazardous to pregnant women. However, if you are pregnant or suspect you may be, you should inform your doctor.
Preparing & During Scan
What do I have to do to prepare for the scan?
Unless you are already in the hospital, you will be tested as an outpatient. There are no dietary or other restrictions prior to MRI. You may like to practice relaxation techniques such as meditation or breathing exercise. These may prove useful during the scan. Immediately prior to the scan, you will be asked to remove all metal objects including:
- Glasses, dentures, hearing aids, jewellery, wallets, credit cards and coins, hair pins/clips
- You may also be asked to remove any excess make-up.
You will then be provided with a hospital gown to wear during the procedure.
What will happen during the scan?
The MRI scanning procedure is very simple. You will be asked to lie very still on a padded ‘bench’ which is then moved slowly into the scanner. The scanner itself is a long, well-lit tunnel, open at both ends. If particular information is required about specific organs, you may be given an injection of a special fluid (contrast agent) prior to the procedure, to allow for greater detail.
During the examination, you will hear a loud knocking sound. This is just the machine working during the scan. Throughout the procedure, you will be in voice contact with MRI staff, who will keep you informed of what is happening.
Will I feel anything during the scan?
No, however, the enclosed nature of the scanner may cause some people to experience certain levels of anxiety. If you have any history of panic reactions or feel this may be a problem, you should talk to your doctor and inform the radiographer prior to the examination. Many people have found talking to someone, wearing special reflective glasses and/or listening to their own music or relaxation tapes helpful during the procedure. In severe cases, a sedative can be provided.
After MRI Scan
How long will the scan take?
The MRI scan will take from 30 to 60 minutes, averaging 40 minutes, depending on the amount and type of information required. During this time, you must lie very still, as any movement can cause an unclear sequence of pictures which may then need to be repeated.
What happens after the scan?
You may leave the hospital immediately after your scan. However, if you have had a sedative, it is advisable that you have someone to accompany you home. Your pictures are interpreted by the radiologist and the images and results are then sent to your neurologist as soon as possible.