MRI (Magnetic Resonance Imaging)

Magnetic Resonance Imaging (MRI), is a very good means of obtaining fine detail and highly diagnostic images of your body without the use of X-rays or any other form of ionising radiation. Instead it uses a very powerful magnet and radio waves with similar frequencies to those used by commercial FM radio stations

MRI is provided at Hagley Radiology (3T) , St Georges Radiology and Southern Cross Radiology (both at 1.5T)

WHAT WILL THE EXAMINATION INVOLVE ?

You will be asked to lie on our examination bed, which will be raised up and into the magnetic field. You will find yourself in a surprisingly airy and well-lit, open-ended cylinder just over 1 metre in length. It remains open at both ends for the entire duration of your scan.

Once in position it is most important that you keep as still as possible as movement detracts from the quality of images obtained. You will hear a variety of loud noises but we will provide you with either earphones or earplugs (depending on examination type) to compensate for this. If your examination allows for the use of earphones, we will play you music of your choice or a FM radio station. You are more than welcome to bring a CD or cassette of your own if you prefer.

Most examinations typically run for 15-25 minutes although some scans may last for up to an hour. The radiographer will be in contact with you at regular intervals during the scan to ensure that you are still comfortable and to let you know how long each part of the scan will take. For some examinations a contrast agent is required to provide a complete diagnosis. This is a substance called Gadolinium, and is injected into an arm. It is safe and painless. The radiographer will, wherever possible, talk to you about this prior to the scan and ask you to complete a consent form.

PREPARATION

Please wear comfortable clothes without metal if possible. We can provide either a gown or track pants. You will also need to remove jewellery (including wrist watches and body piercings) and any other metallic objects from your person. It is not usually necessary to remove wedding bands. We do provide secure lockers for the storage of removed items, but it is preferable that you leave items of value at home.

There is no need to stop medication for the examination, and you may eat and drink normally unless instructed otherwise.

RESULTS

These are usually sent to your specialist within two working days of your scan. However if your appointment with your specialist is sooner than two working days it is important that you let our staff know so that we can provide an urgent report.

IS IT SAFE ?

There are no known side affects associated with MRI, but there are several situations in which a scan should not be carried out, these include certain implants such as heart pacemakers, surgical clips within the brain and metal fragments in the eye, however most orthopaedic implants such as artificial hips are quite safe.You will be asked to complete a safety screening form prior to your scan and a radiographer will go through this with you to ensure that your examination will be completely safe and to answer any questions you may have regarding the scan.

It may not be advisable for pregnant women to have MRI scans, although there is no evidence that a hazard exists. In certain cases a scan may be recommended as it may be safer than x-ray during pregnancy.

HOW DOES IT WORK ?

The body is made up of tiny structures called atoms; MRI uses Hydrogen atoms (a major component of water, which makes up approximately 95% of the body). At the centre of each hydrogen atom is a single proton (this is a tiny particle with a positive charge) which has its own tiny, randomly orientated magnetic field. When placed into the strong magnetic field of the scanner the random magnetic fields of the all the Hydrogen protons line up in the same direction. They also begin to spin at a certain frequency. We then transmit a radio signal at the same frequency and after a very short period of time we get a signal back from your body. This signal is detected by the scanner and processed by a powerful computer, giving us tremendously detailed images of the part of your body under examination.

We want your examination to be as relaxing as possible. Please don't hesitate to ask any questions, no matter how seemingly unimportant you might think they are, our staff are only too happy to answer them, hopefully making the scan as enjoyable and as safe an experience as we can.

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