What is MRI and How Does it Work
Having an MRI scan
If your neurologist has suggested that you have an MRI scan, you may be wondering what is involved. Below are a few points to explain what you can expect during the scanning procedure.
Before scanning begins
When you arrive at the MRI unit, you will be asked to lie on a bed which is then wheeled into the MRI scanner. Inside the scanner you will be lying in a tunnel, whose diameter is slightly larger than shoulder width. As a result you may feel cramped, even claustrophobic, but the process is over in a relatively short amount of time.
You will be asked to lie still. In fact, you will need to keep the part of the body the doctor wishes to scan completely still. In MS, the brain and spinal cord are most often scanned.
During a scan of the head, you can move your hands and feet, and you can swallow normally but the head must remain in a fixed position. Some hospitals may fasten your head to the bed by the use of straps or provide plenty of padding.
If the spinal cord is scanned, you will need to keep that part of the body completely still. These measures help to provide a clear picture from the MRI machine.
If the doctor has requested that a contrast agent (e.g. a gadolinium-containing substance such as Magnevist®) is used to enhance scan, it will be given to you intravenously over a period of 1-2 minutes. The doctor will wait about five minutes before performing the scan to ensure that sufficient contrast agent has reached the brain. After the scan, the contrast agent is eliminated from the body in the urine.
What you can expect during scanning
You may feel cold during the scan, depending on the hospital where you have your MRI examination. Hospitals seeing only MS patients may keep the temperature inside the scanner room somewhat chilly (18-19°C), because people with MS tend to feel more comfortable in cooler temperatures.
Once the scanning process begins you will hear a 'clanking' sound, whose loudness is dependent on the strength of the magnet (for very strong magnets this can be quite loud). Don't be alarmed! This is the magnet generating its magnetic field. It is a normal sound which can be mistaken for a broken machine by those having the scan. The hospital staff will probably give you earplugs or earphones to alleviate the noise.
Many MRI facilities also have an intercom system so the doctor can speak to you during the scan. There will probably also be a buzzer present so you can contact the staff if there is a problem. Even though you are in a small space, you are not alone. Several hospital staff are close by and easily contacted through the intercom and buzzer systems.
How long does an MRI take?
The length of time for an MRI scan varies depending on the hospital and the number of body areas that need to be scanned. On average, an MRI scan to diagnose MS will take about 30 minutes.
MRI is safe and painless, but it can be an unpleasant experience for some because there is little room to move and the noises from the machine can be loud. Both of these circumstances can be unnerving if you are not prepared for them. However, MRI takes a relatively short amount of time to complete and it provides the doctor with critical information for the diagnosis of MS and for assessing treatments.
Looking to the future
From its early clinical beginnings in the field of MS just 10 years ago, MRI has become established as a key tool for evaluating the disease. This remarkable technology is constantly evolving and continuing developments in MRI and related techniques offer the prospect of gaining an even greater understanding of MS in the future.
