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Magnetic Resonance Imaging (MRI)
The cause of multiple sclerosis (MS) may not be known, but the effect is very clear. One of the best ways to see the damage caused by MS is by the use of magnetic resonance imaging (MRI). MRI is an imaging modality that uses non-ionizing radiation to create useful diagnostic images. MRI was initially called Nuclear Magnetic Resonance Imaging (NMRI) after its early use for chemical analysis. The "Nuclear" was dropped off about 25 years ago because of fears that people would think there was something radioactive involved, which there is not.

MRI is used to distinguish pathologic tissue such as a brain tumor or MS lesions from normal tissue. It will show any scarring that has happened in the past and can show any new scarring from current damage. Widespread use of MRI has revolutionized the ability to diagnose MS. Disease-related changes in the brain or spinal cord are detected by MRI in more than 90% of people suspected of having MS.

MRIs can often detect damaged areas in the brain or spinal cord that would be missed by other imaging techniques such as a computed axial tomography (CAT or CT) scan. Unlike CT and PET, MRI doesn't use ionizing radiation. In addition, it has a higher spatial resolution than both modalities. Another major advantage of MRI is its ability to image tissues.

At the present time, MRI scans are considered the best test to help diagnose MS. However, 5% of people with MS don't have abnormalities detected on a MRI scan, because of this a "negative" scan doesn't completely rule out MS. In addition, some common changes from aging of a healthy person may look like MS on a MRI.

There is little to no preparation required for patients before an MRI scan. Upon arrival, some facilities may ask that you change into a gown. As magnets are used, it's critical that no metal objects are in the scanner, meaning that you will be asked to remove any metal from your person that may interfere with the machine. Sometimes, patients will be injected with intravenous (IV) contrast liquid to improve the appearance of a certain body tissue. The radiologist will discuss the MRI scanning process and answer any questions about the procedure.

An MRI is a 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 and once it begins can be very noisy. During the scan, it's very important to try and stay still. Any movement will disrupt the images created, much like a camera trying to take a picture of a moving object.

Some facilities that operate an MRI will have music and headphones available which can mask the noise, or you can simply focus on the rhythm of the sounds and it can within itself be relaxing. The acoustic noise is from the switching of field gradients causes a change in the Lorentz force experienced by the gradient coils, producing minute expansions and contractions of the coil itself. As the switching is typically in the audible frequency range, the resulting vibration produces the loud clicking or beeping noises.

What to Expect During an MRI

An MRI scan is the most important test for diagnosing and monitoring MS, as well as many other neurological diseases and disorders. The test itself doesn't hurt, but if you have never had the pleasure, it can be a strange and unusual experience for the first time. Knowing what to expect during an MRI can help make that experience less stressful. It's important that you be as comfortable as possible, and there are a number of ways to help you do this.

Getting Ready Prior To The Scan:
• Wear comfortable clothing, not anything that will be restrictive or tight while lying down but not baggy enough to hang over the table and get caught.
• Wear clothing that if good for you at the temperature the room is kept at. Ask and find out if it will be cold or warm prior to the exam. Dress for heat so you can undress to a minimum of thickness. It can get hot in the MRI machine.
• Bring socks if your feet get cold because they will be sticking out of the machine.
• Don't wear anything with metal, or you will be asked to take it off, which includes any jewelry and bras, which usually have metal clasps at the back. An exercise bra may be a good choice for women, they shouldn't have metal and may be kept on.
• You will be asked to complete a questionnaire, which asks about any metal which you might have in your body, including screws, cochlear implants, artificial joints, etc.
• You may be allowed to leave your clothes (if there are no metal zippers, snaps or buttons) on or be asked to change into a hospital gown.
• An IV port may be inserted at this point for gadolinium (contrast material) administration later or it may simply be injected at the beginning.
• If you are claustrophobic, don't like to be confined, or very scared of the procedure itself, don't be afraid to ask for a sedative.
• If you have a cough or cold, consider taking a cough suppressant or decongestant prior to you visit. You may be reminded not to cough or move during the scan, and this includes scratching any itches that arise. If you do move in any manner during the scan, they may have to begin that sequence over again.

In The Scanning Room:
• You will be taken into the MRI room and asked to lay on the table, which is fairly narrow and hard and slides out from the machine, so make sure any clothes are not hanging over. Some centers allow a friend to stay with you.
• You will probably be given earplugs, put them in well because it will get loud if they move out of place.
• If the room feels cold, ask for a blanket, but remember that it will need to remain on since you can't move during the exam. Ask if you can call them to have it removed if you get too hot.
• If you are receiving a scan of your brain, cushioned pads will be positioned on either side of your head to keep it still. A "surface coil" which resembles a plastic cage will be fit around your head. If it bothers you, let them know, it can be removed for scans of your spine.
• If available, ask for a pad to place under your knees. This is much more comfortable than having your legs straight for an extended time.
• The technician will slide the table into the machine before he leaves the room.
• Once you are comfortable, the technician will leave the room and secure the door behind them for your safety. Most facilities have a speaker so the technician can talk to you during the scan and a window or cameras so they can see you.

During The Scan:
• Breathe steadily and regularly and try not to worry, breathing this way won't affect the images. Those who can relax this way may find that it's so relaxing, they may actually get close to falling asleep during the scan.
• Practice creative visualization. Picture the most pleasant, relaxing place that you have ever been. Then imagine that you are there. This can help those who are nervous or don't like confined spaces.
• The technician may tell you how long each sequence will last after one ends and then next begins.
• The machine itself makes very loud banging or clanging sound for the duration of each sequence. You may also experience some vibration. After each sequence, there's usually a short pause of 5 or 10 seconds, and then the sequence should begin.
• If not give just prior to starting, then about halfway through the procedure, the gadolinium (if it's being used) will be injected, either with a syringe or into the IV port that has been inserted for this purpose. It usually feels a little cold and may sting slightly, but only for a short time.

The duration of the entire test depends on:
• What is being scanned: the brain, the whole spine, parts of the spine or everything
• If contrast will be used: will contrast material like gadolinium be used, which is used to determine if a lesion is "active" (having a relapse), as opposed to having symptoms from a lesion that is no longer active.

The test could be as short as 15 minutes or as long as 2 hours.

The Brief History of MRI

On July 3, 1977, the first MRI exam on a live human patient was performed. MRI has become an extremely useful non-invasive method for imagining internal bodily structures and diagnosing disease.

• 1882 - This history begins with Nikola Tesla, when he discovered the Rotating Magnetic Field in Budapest, Hungary. This was a fundamental discovery in physics.
• 1937 - Columbia University Professor Isidor Rabi recognized that the atomic nuclei show their presence by absorbing or emitting radio waves when exposed to a sufficiently strong magnetic field.
• 1946 - Felix Bloch, working at Stanford University, and Edward Purcell, from Harvard University, discovered NMR. NMR spectroscopy was then used as means to study the composition of chemical compounds.
• 1950's - Herman Carr created a one-dimensional MR image.
• 1970 - Raymond Damadian, a medical doctor and research scientist, discovered that different kinds of tissue emit response signals that vary in length, and that cancerous tissue emits response signals that last much longer than non-cancerous tissue. Later he filed his idea for using MRI as a tool for medical diagnosis with the U.S. Patent Office.
• 1974 - Raymond Damadian, was granted the world's first patent in the field of MRI. By 1977, Dr. Damadian completed construction of the first whole-body MRI scanner.
• 2003 - Nobel Prize in Physiology or Medicine was awarded to Paul Lauterbur and Peter Mansfield for their discoveries concerning MRI. Lauterbur introduced the second dimension of spatial orientation, and Mansfield further developed the utilization of gradients in the magnetic field showing how the signals could be mathematically analyzed.

The medical use of MRI, as with everything electronic at that time, developed rapidly. The first MRI equipment for medical use were available at the beginning of the 1980s. In 2002, approximately 22,000 MRI were in use worldwide, and more than 60 million MRI examinations had been performed.