What is Magnetic Resonance Imaging?
Magnetic Resonance Imaging (MRI) is a non-invasive medical imaging test that helps physicians diagnose and manage medical conditions. MR imaging uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of cartilage, bones, muscles, tendons, ligaments, nerves, intervertebral discs and almost all other internal body structures. The images are then examined by the radiologist on a computer monitor inorder to make the diagnosis.
MR scans have advantages over other methods of diagnostic imaging. Detailed MR images allow physicians to better evaluate parts of the body and certain diseases that may not be assessed adequately with other imaging methods such as x-ray, ultrasound or Computed Tomography (also called CT or CAT scanning). Additionally, MRI does not use ionizing radiation (X-rays).
At SRG, MRI is commonly used to evaluate:
- Musculo-skeletal system which includes the pelvis, hip, knee, ankle and foot, shoulder, elbow, wrist, hand and fingers.
- Neuorological system which includes the brain, internal ear and blood vessels (MR Angiography).
- Spine which includes the cervical, thoracic and lumbar spine.
- The shoulder and hip (following an arthrogram injection).
Preparation for your MRI
Appointments
You will need to make an appointment for this examination. To do so, call us on +64 (9) 523 7054 and choose option 2 at the prompt.
On the day of your examination
Because they can interfere with the magnetic field of the MRI unit, metal and electronic objects are not allowed in the exam room. Some objects can become projectile, causing serious injury to yourself or others.
Jewellery and other accessories should be left at home if possible, or removed prior to the MRI scan. If unsure about the compatibility of your jewellery with the scanner, please contact us.
These items may include:
- watches, mobile phones, credit cards and hearing aids, all of which can be damaged.
- jewellery, pins, hairpins, metal zippers and similar metallic items.
- some removable dental work.
- pens, pocketknives and eyeglasses.
You will be asked to change out of your clothes and into a gown for the scan.
Unless you are told otherwise, you may follow your regular daily routine and take medications as usual. Please ensure that if you are taking regular pain relief, you continue to do so for your comfort during the scan.
Contrast Agents
Some MRI examinations may require that the patient receive an injection of gadolinium based contrast into the bloodstream. You will be asked if you have allergies, however, Gadolinium based contrast agents used in MRI are very safe and do not contain iodine, making it less likely to cause an allergic reaction.
You must advise us if you have kidney disease or diabetes and especially if you are undergoing renal dialysis. These conditions may prevent you from having the contrast agent.
Pregnancy
Women should always inform the MRI technologist if there is any possibility that they are pregnant. Because the risks of an MRI exam to the unborn foetus are unknown, pregnant women should not have this exam unless the potential benefit from the MRI is assumed to outweigh the potential risks.
Claustrophobia
If you have claustrophobia (fear of enclosed spaces) or anxiety, you may opt to receive a sedative. This must be organised with SRG at least 24 hours prior to your scan.
Surgically Implanted Items
In most cases, an MRI exam is safe for patients with metal implants, except for a few types. People with the following implants cannot be scanned and should not enter the MRI area:
- cardiac pacemaker
- internal (implanted) defibrillator
- cochlear (ear) implant
You should tell the MRI technologist if you have medical or electronic devices in your body, because they may interfere with the exam or potentially pose a risk.
Examples include:
- clips used on brain aneurysms
- cardiac or carotid shunts
- artificial heart valves
- implanted drug infusion ports
- infusion catheter
- implanted electronic device, including a cardiac pacemaker
- artificial limbs or metallic joint prostheses
- implanted nerve stimulators
- metal pins, screws, plates or surgical staples.
In general, metal objects used in orthopaedic surgery and abdominal surgeries pose you no risk during an MRI. However, if there is any question of their presence, an x-ray may be taken to detect the presence of any metal objects.
Metallic Foreign Bodies
Those people who have had metal in their eyes from grinding metal should contact us before their scan. In some cases an x-ray will need to be taken to ensure that all the metal has been removed.
Other metallic foreign bodies such as shrapnel may also require an x-ray prior to an MRI.
Tattoos
Dyes used in tattoos may contain iron and could heat up during MRI, but this is rarely a problem.
Fillings and Braces
Tooth fillings and braces usually are not affected by the magnetic field but they may distort images of the facial area or brain, so the radiologist should be aware of them.
After your scan
Reporting
Results of procedures are sent directly to your referring physician. MRI scans are reported within 12 to 24 hours after your scan. Reports are faxed or sent electronically through the secure healthlink service for immediate review.
Your Images
Images are available in film or CD format and will either be sent directly to you or your referring physician, depending on the instructions received at referral. Reports can be obtained from your referring physician.
Images on Disc
If you have been given an SRG CD containing images of your scan, you are able to view these on your computer.
Learn more about Images on Disc