What happens in MRI?

The MRI scanner consists of a large circular very powerful magnet, a scanning table complex computer systems and radiofrequency coils.  It does not use ionising radiation (X-rays) and it produces extremely detailed images of the part of the body being examined.

The patient may be asked to change into a hospital gown before entering the scan room.  All loose metallic items e.g. glasses, dentures, hearing aids, jewellery, coins, keys, credit/bank cards, mobile phones, hairclips, cigarette lighters etc must be removed before entering the scan room and maybe locked in a locker (key to be kept in the MRI control area)  for the duration of the scan. 

The MR radiographer (operator of the scanner) will position the patient on the table and move the patient into the scanner.  The scanner is illuminated, has a fan for air circulation and remains open at both ends at all times.  The area of the body to be scanned must be in the centre of the magnet for the best quality images to be obtained. 

A bell (resembling a rubber ball) will be provided during the scan so that the patient has constant contact with the MR radiographer.  The patient should not feel any pain or discomfort during the scan and should alert the radiographer by squeezing the bell if he/she has any difficulty during the scan.  If the patient has any concerns about the scan they should discuss them with the radiographer before the scan.

During the scan the patient will hear a series of varying loud tapping, knocking and buzzing noises when the MRI is scanning.  Headphones or earplugs will be given to the patient to wear to help block out the noise.  Depending on the scan type, the patient may be allowed to listen to the radio during the scan.

Scan times vary from a number of minutes to a couple of hours depending on the type of study requested and the number of body areas to be imaged.  It is very important that the patient remains as still as possible for the duration of the examination.  Movement during the scan may result in sets of images being “blurred” and these sets of images may need to be repeated significantly increasing the length of the scan.

Some examinations may require the injection of a contrast medium through a small needle inserted in a vein (usually in the arm).  This substance may improve the visualisation of certain structures within the body.

Once all the images are acquired and checked the patient is free to leave the department.  A report of the scan will be sent to the doctor who referred the patient for the scan and who will discuss the result with the patient.