What is an MRI?
Invented in 1977, the MRI offers one of the most sophisticated and important diagnostic procedures available today. It is non-invasive, carries no risk of radiation and is painless. It is less commonly used than CT-scans mainly because MRI machines are extremely expensive and, as a result, there aren’t enough of them to meet demand in Canada’s public health care system.
This is why MRI private clinics usually offer the fastest way to get the service you need. Timely Medical Alternatives can arrange these scans for you.
The abbreviation MRI stands for Magnetic Resonance Imaging and refers to the machine’s ability to create pictures of the inside of your body, using magnets and radio waves.
How does an MRI differ from other procedures?
Unlike X-rays and CT-scans, MRIs do not use any radiation – a fact many people appreciate.
As well, an MRI can take pictures from almost any angle – sideways, like a slice of bread, lengthwise, as a layer in a cake, or frontwise, as a drawbridge being lowered. And, the difference between normal and abnormal tissue is often clearer on the MRI scan than on a CT scan.
MRIs are also better at capturing images of soft tissue (whereas X-rays and CT-scans generally do a better job with bone.)
How is an MRI most useful?
An MRI is often especially helpful in diagnosing, visualizing or evaluating the following:
- Lumbar disc degeneration or sciatica
- Neck disc degeneration
- Knee injuries
- Shoulder injuries
- Brain tumours
- Masses in the soft tissues of the body
Are there risks?
Because the MRI uses such a powerful magnet, it’s important that no metal be anywhere in the room – especially not on or in you! If you’ve ever been a metalworker, you should be carefully screened before taking the test. Small metal fragments that might be in your eye pose a significant risk as the magnet can cause them to move through your tissue, damaging it. (This risk can be ruled out with a skull X-ray.)
If you have any of the following metallic objects in your body, however, you should not have an MRI:
- Inner ear (cochlear) implants
- Brain aneurysm clips
- Certain artificial heart valves
- Older vascular stents
- Recently placed artificial joints
- Certain types of dental implants
In addition, pregnant women are advised to avoid MRIs – especially during the first 12 weeks of pregnancy — because the effects on the developing fetus are unknown.
Most orthopedic implants are usually not a risk factor, because they are embedded in bone. Orthodontic braces on your teeth are usually fine too, but be sure to double-check with the MRI clinic technicians when you make your appointment.
How is the procedure performed?
When you go for your appointment at the MRI clinic, technicians will ask you to lie on a narrow table, which will slide into the middle of the machine during the procedure. Whether you travel into the machine headfirst or feet-first depends on the type of exam being performed.
Be prepared: the MRI machine makes an enormous amount of noise! This is caused by the electrical current in the wires of some of the magnets. You will be given earplugs or stereo headphones to help muffle this noise. Some MRI clinics will even let you bring your own cassette tape or CD to listen to, so be sure to ask in advance.
You will need to keep very still during your MRI. The exam can range from 20 minutes to 90 minutes or more. Even slight movements can result in distorted images, so it is important to keep still or the test may have to be repeated.
Some exams require that a special dye be given before the test. The dye is usually given through an intravenous line (IV) in your hand or forearm. It helps the radiologist see certain areas more clearly.
During the MRI, the person who performs the test will watch you from a room next door and talk to you through a microphone.
How should I prepare for the procedure?
You should wear comfortable, loose fitting clothing that is free of metal (including metal zippers). If you are claustrophobic, please alert the MRI clinic when booking your appointment. You may be given a mild sedative.
If your procedure requires a dye injection, you may need to fast for several hours beforehand. Just follow the instructions you will receive from the MRI clinic.
Because of the powerful magnets in the machine, technicians will ask you to remove all of the following items before entering the procedure room: jewellry, watches, credit cards, hearing aids, pins, hairpins, pens, pocketknives, eyeglasses and removable dental work.
Who interprets the results and how do I get them?
A trained and certified radiologist at the MRI clinic will analyze the images and write a report that will be given to you and to your doctor if you wish. Additionally, a CD with the MRI images will also be given to you.