What is Magnetic Resonance Imaging?
Magnetic resonance imaging (MRI) is a scanning procedure that uses strong magnets and radiofrequency pulses to generate signals from the body. These signals are detected and processed by a computer to create images (or pictures) of the inside of your body.
The MRI scanner is generally shaped like a large, covered box with a tunnel passing through it. A table, on which you lie, slides into the tunnel.
How do I prepare for my MRI?
Safety in the MRI scanner is vital. The strong magnetic fields can attract and interfere with metal objects that you might have in or on you (including electronic and magnetic devices). To ensure it is safe for you to have an MRI, you will be required to complete a safety questionnaire.
If you have a pacemaker or other implants, it is important to tell reception when making a booking. An alternative test might need to be arranged.
Objects in your body that can cause particular harm or be damaged include: pacemakers, aneurysm clips, heart valve replacements, neurostimulators, cochlear implants, metal fragments in the eye, metal foreign bodies, magnetic dental implants and drug infusion pumps. Some of these implants, particularly more recent devices, might be safe to go into the MRI scanner, but must be accurately identified for the scan to proceed.
You should take any documents about your implants to the practice before booking an appointment. These can help to correctly identify the type of implant to assess if it is safe for you to have the MRI.
It is important that you do not wear any makeup or hairspray, as many of these products have tiny metal particles that could interfere with the scan and reduce the quality of the images. They might cause the area to heat up and, on the rare occasion, burn your skin.
You will not be able to take anything with you into the scan room, and there are usually lockers available. It is easier if you leave objects such as watches, jewellery, mobile phones, belts, safety pins, hairpins and credit cards at home.
Fasting (going without food) for a MRI procedure might be required in some cases. When you make your MRI appointment, you will be advised of any fasting requirements.
Please bring any previous MRI, X-ray, computed tomography or ultrasound films. The radiologist might like to review the older studies or see if your condition has changed since your last scan.
What happens during the MRI?
The MRI procedure will be thoroughly explained to you. If you have any questions, please ask the radiographer, who will be operating the MRI scanner, as it is important that you are comfortable and know what will be happening. The radiographer will be able to see you from the control room throughout the scan. You will usually be asked to change into a gown
You will be asked to lie on the scan table and given a buzzer to hold. When you squeeze it, an alarm sounds in the control room and you will be able to talk to the radiographer.
The MRI scanner is very noisy during the scans. It is at a noise level that can damage your hearing. You will be given earplugs or headphones to reduce the noise to safe levels.
In some cases, a contrast agent or ‘dye’ called gadolinium contrast medium will be injected. This highlights the part of the body being scanned, which can give more information to the radiologist who is assessing your problem.
The part of your body to be scanned will be carefully positioned and gently secured, so you are comfortable and more likely to remain still. This part will then have special antennae (coils) positioned around it to pick up signals from your body for the computer to create images. The coils are usually encased in a plastic pad or frame. Depending on the part of the body being scanned, they might be wrapped around your shoulder or lie on top of your stomach. A frame containing the coils can be used, for example, around your knee or wrist, and also for your head and upper neck. Some coils are in the mattress of the scan bed, used when your back is being scanned.
The scan table will then move into the centre of the machine. Your head might be inside or outside the scanner, depending on the part of the body being scanned.
When the scan begins, you will hear a loud knocking noise that continues during each scan. Scanning is not continuous, and each scan varies in length from about 1 to several minutes, with a break in between. You will be able to talk to the radiographer between each scan and can press the buzzer if you are not comfortable or want to come out of the machine at any time.
You need to lie still and hold your position during the scan. In general, you can breathe normally. Occasionally, during some types of MRI, you will need to hold your breath. Breathing and movement can make the images blurry and assessment of your problem more difficult.
How long does the MRI take?
The scan can take between 10 minutes to over an hour to complete. This depends on the part of the body being imaged and what type of MRI is required to show the information. Before the scan begins, the radiographer will tell you how long the scan takes, so you know what to expect.
Do I need an appointment?
Yes, appointments are essential.
Is there any special preparation?
Patients will be notified of any special preparation at the time of booking, as some of the examinations will require fasting for four to six hours prior to the appointment.
In some cases, patients will be asked to attend the appointment one hour early to drink a special fluid. This will be discussed at the time of booking.
How much does it cost?
The cost of the scan may be claimed from Medicare under certain circumstances. Unfortunately, these criteria are extremely strict, and some patients are not eligible to claim a Medicare rebate and are therefore required to pay a fee at the time of consultation – this will be discussed at the time of booking.
What to bring:
• Referral from your doctor.
• Previous films and/or reports. If you have had a previous examination in our practice, these can be electronically retrieved, and you do not need to bring them with you.
• Method of payment including Medicare, Health or Pension Card.
