Multiple Sclerosis MRI: What is Magnetic Resonance Imaging?
Magnetic resonance imaging, MRI, has become one of the most important diagnostic tools for MS. It is also being used to provide vital research into how the disease develops.
An MRI scan can take detailed images of the brain and spinal cord showing up clearly any areas where there is scarring of the protective myelin sheath which covers the nerve cells. The symptoms of MS are thought to be caused by damage to this protective tissue.
This type of scan can show the size, distribution and extent of the lesions and coupled with a detailed medical history and neurological examination can go a long way in confirming a diagnosis of MS.
It's a perfectly painless procedure but can be alarming for patients undergoing their first scan. The patient lies on a table which moves into a tube containing a large magnet (be warned that the machine is very noisy!). The magnet induces different chemicals in the body to let off radio signals. These signals are translated into slice by slice pictures showing cross sections of the brain and spinal cord.
It's not a wholly conclusive diagnostic test but MRI reveals abnormalities in 95% of MS patients. It's also a useful tool for ruling out other conditions, such as a brain tumor, which may be causing similar symptoms.
MRI is also becoming a very important part of clinical trials. Because it can show changes in the disease's activity, it's used to assess the effectiveness of new therapies and drugs and their impact on symptoms.
Magnetic resonance imaging is a much more precise diagnostic tool for identifying Multiple Sclerosis than the more traditional CT scanning which involves computer-controlled X-ray images. With MRI it's possible to take images from every angle and is particularly useful for getting a detailed picture of the brainstem and posterior brain, which are difficult to see on a CT scan. CT scans (also known as CAT scans) only show pictures horizontally and they are not nearly as detailed as MRI which gives a much clearer picture of the difference between normal and damaged tissue. MRI can pinpoint the exact location and size of any scarring in the myelin sheath surround the nerve cells. MRI is also regarded as being safer because it doesn't involve radiation.
In the UK MRI scanning is widely available on the national health service (NHS) but because of the multi million pound cost of such sophisticated machines most hospitals only have one available so patients often face a long wait for a scan. The luckier patients get referred to specialist neurological hospitals which usually have more than one MRI scanner. This situation is reflected throughout most of the developed world.
An increasing number of private hospitals in Britain are purchasing MRI scanners and some health authorities have a referral scheme whereby an MS patient can be scanned at a private hospital which then recoups the cost from the NHS.
Medical insurers sometimes cover the cost of this diagnostic procedure in those with suspected MS although this depends on the individual policy.
MRI scanning was only introduced in the late 1970s. In those days there were just a small number of the machines in the USA which today has thousands of scanners.