MRI Scans - FAQ

Written by Dr Joy Yip - BSc (Med) MBBS (UNSW) MPH (USYD)

What does MRI stand for?

MRI stands for magnetic resonance imaging. It has been used in medical imaging since the 1980’s. It involves the production of a magnetic field that causes hydrogen atoms in the body to align in a certain direction. When the field is switched off, the atoms return to their normal alignment sending off a signal that can be interpreted by a computer to produce images.

How much radiation is there from an MRI scan?

None that you need to worry about. There is no ionising radiation from an MRI scan as it uses magnetic and radio waves. This means that there is no increased risk of cancer and it is theoretically safe in pregnancy. This does not mean it is safe for everyone! Because a powerful magnetic field is created, people with metal implants should check if they are suitable for MRI scans as the magnetic field could dislodge metal parts depending on their size and location. Also, MRI scans can cause pacemakers or defibrillators to malfunction with potentially disastrous and lethal consequences.

Who should not have an MRI?

People with the following:
  • Brain aneurysm or haemostatic clips - may dislodge
  • Cardiac pacemaker or cardiac defibrillator - may malfunction
  • Cochlear implants - may move or malfunction
  • Insulin pumps - may malfunction
  • Metal shrapnel / bullets / shavings - may dislodge
  • Metal splinters in the eye - may dislodge
  • Claustrophobia / panic attacks*

*An MRI scan requires a person to lie perfectly still in a dark enclosed space for a considerable period of time. The loud knocking and banging noise produced by the magnetic coils are distressing for some people.

How loud is an MRI scan?

An MRI scan may get as loud as 110 decibels. Wearing provided earplugs or earphones will reduce this. For comparison, a loud motorcycle is around 100 decibels and a loud rock concert is around 115 decibels. For most people, the character of the noises heard i.e. banging and knocking is more disconcerting than the actual noise level. MRI scans are not loud enough to cause pain or permanent hearing damage.

Does an MRI affect my clothing or credit cards?

When having a scan, you will be asked to remove all metal from your body such as earrings, rings, necklaces, bra straps, belt buckles and shoes. If something like earrings are forgotten, they won’t rip out of the ears but they will interfere with the images produced. Credit cards will be wiped. Keep them safe outside!

How much does an MRI cost in Australia?

This depends on the area of the body being imaged. In some situations, an MRI may be covered by Medicare such as for pensioners or war veterans (DVA) or for particular scans ordered by specialists. For most scans, expect to be out of pocket between $100 and $500. While this may sound expensive, MRI scans overseas costs thousands of dollars. For perspective, an MRI machine costs millions of dollars.