MRI scans can be used to detect changes in the activity of different regions of the brain. Radio waves, not an x-ray, are used and the MRI scanner, using computer technology, can build up very detailed pictures. Not everyone with epilepsy will require an MRI scan.WHAT IS MAGNETIC RESONANCE IMAGING?
Magnetic Resonance Imaging or MRI is a scanning technique that produces very clear, detailed pictures of the brain (and other parts of the body). These pictures are very much more detailed than those from other scanning techniques. By using a combination of new techniques to acquire MRI scans and subsequently process the data, it is possible to identify the causes of the seizures in many people whose epilepsy arises in one part of the brain. Small tumours, developmental abnormalities, abnormal blood vessels and minor brain damage are now routinely visualised and it is now possible to diagnose more subtle abnormalities that may also cause epilepsy. It is important to remember that MRI is a diagnostic technique and not a form of treatment.
HOW DOES MRI WORK?
MRI uses a very strong magnetic field, far stronger than the earth’s magnetic field, and this scans the hydrogen protons within the human body. Very sophisticated electronic hardware and computer software is then used to produce the images on to both a computer screen and on to film so that a specialist technician can study them.
WHY ARE MRI SCANS HELPFUL IN EPILEPSY?
An MRI scan gives far better anatomical details than other diagnostic techniques and in epilepsy this has meant that even very small abnormalities, which may have been missed by other scans, can be seen. In some people it is possible to remove the abnormal area by neurosurgery. In clinical practise MRI is now an essential investigation providing information about cause, prognosis and type of epilepsy.
ARE THERE ANY SIDE EFFECTS FROM MRI?
Unlike with x-ray, MRI is not known to have any harmful side effects. Some people may find the enclosed space claustrophobic. If you suffer from claustrophobia (fear of enclosed spaces) you will need to discuss this with the doctor referring you for the scan.
WHAT IS INVOLVED IN HAVING AN MRI SCAN?
Before having a scan it will have to be determined whether there is any reason why a scan should not be carried out and a form will have to be completed. Because of the strong magnetic field people with pacemakers, cerebral aneurysm clips and some other surgical implants will not be able to have an MRI scan.
Before having the scan any jewellery, hairclips, hearing aids, credit cards, coins, or keys, which could interfere with the scanning procedure, will have to be removed.
The person having the scan will be asked to lie down on a flat surface that will then move inside the scanner. The procedure is painless but earplugs are usually available as the noise made by the scanner is very loud. A two-way intercom means that there is constant contact whilst the scan is being carried out. Usually the scan will last about half an hour and all the person has to do is to keep as still as possible.
WHAT ELSE IS MRI USED FOR?
In addition to providing anatomical pictures, research is showing that MRI potentially has other uses. For instance, with MRI spectroscopy, it is now possible to measure the amounts of various chemicals within the brain, which gives information about the health and viability of brain cells, and to determine how and where in the brain, these are affected in people with epilepsy.
HOW CAN SOMEONE BE REFERRED FOR AN MRI SCAN?
The possibility of having a scan should be discussed first with the doctor managing the epilepsy treatment. A medical referral either from the GP or consultant will be needed before having a scan at a scanning unit.