What is an MRI?
An MRI (magnetic resonance imaging) is a non-invasive procedure that uses magnetic fields and radio waves to take detailed cross-sectional pictures of the body.
When you might have an MRI
An MRI can be used to look at most areas of the body.
Some examples of what an MRI can be used for:
- find a tumour
- find out how big the tumour is and if it has spread (stage a cancer)
- measure blood flow
- check how well treatment is working.
What to expect at your MRI
An MRI scanner is usually shaped like a large, covered box with a circular tunnel passing through it. You will lie on an examination table that slides into the tunnel. The scan is painless but can be noisy and can take between ten minutes to over an hour to complete. The time required depends on the part of the body being imaged and what type of MRI is being performed.
Some people may feel claustrophobic during an MRI scan. If you feel anxious or uncomfortable in confined spaces, let your doctor or nurse know before the scan.
Safety in the MRI scanner is extremely important. The strong magnetic fields can attract and interfere with metal objects that you might have in or on you (including magnetic and electronic devices). Some of these interactions can cause serious harm so discuss with your medical team beforehand.
Objects in your body that can cause particular harm or be damaged may include pacemakers, cochlear implants, aneurysm clips, neurostimulators, heart valve replacements, metal fragments in the eye, metal foreign bodies, magnetic dental implants and drug infusion pumps. Some of these implants, particularly more recent devices, might still be safe to go into the MRI scanner, but it is important to have these accurately identified before the scan.
In some cases, you might also have an injection of a dye (contrast) during the scan. This is given after a small needle has been placed into a vein (like with a blood test), usually in the arm, prior to the scan. The dye used in an MRI scan can sometimes cause allergies. If you have had a reaction to dyes in a previous scan, tell your medical team or doctor beforehand. You should also let them know if you have conditions like kidney disease or diabetes.
Are there any risks?
An MRI is painless, safe and does not use radiation. Some people may not be able to have an MRI but your doctor and radiographer need to ensure the benefits of having the test outweigh any possible risks for you. It is important to let them know if you have any allergies to dye or if there are any metals in or on you.
If there is a chance you are pregnant, please discuss this with your doctor and tell the radiology practice before having the scan.
If you have any questions or concerns, speak to your doctor or radiologist or call Cancer Council 13 11 20.
Medicare provides a rebate for some MRI scans, but there may be a gap fee you need to pay. Ask your doctor what you may need to pay.
Understanding Cancer Booklets, Cancer Council Australia ©2020
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