MRI and MS - The role of MRI in Multiple Sclerosis

Nikola Tesla discovered the Rotating Magnetic Field in 1882 in Budapest, Hungary. This was a fundamental discovery in physics.

In 1956, the "Tesla Unit" was proclaimed in the Rathaus of Munich, Germany by the International Electro-technical Commission-Committee of Action. All MRI machines are calibrated in "Tesla Units". The strength of a magnetic field is measured in Tesla or Gauss Units. The stronger the magnetic field, the stronger the amount of radio signals which can be elicited from the body's atoms and therefore the higher the quality of MRI images.

1 Tesla = 10,000 Gauss

Low-Field MRI = Under .2 Tesla (2,000 Gauss)

Mid-Field MRI = .2 to 0.6 Tesla (2,000 Gauss to 6,000 Gauss)

High-Field MRI = 1.0 to 1.5 Tesla (10,000 Gauss to 15,000 Gauss)

In 1937, Columbia University Professor Isidor I. Rabi working in the Pupin Physic Laboratory in Columbia University, New York City, observed the quantum phenomenon dubbed nuclear magnetic resonance (NMR). He recognized that the atomic nuclei show their presence by absorbing or emitting radio waves when exposed to a sufficiently strong magnetic field.

Professor Isidor I. Rabi received the Nobel Prize for his work. He is one of 28 Nobel Laureates from the Pupin Physics Laboratory in New York City.

Raymond Damadian, a physician and experimenter working at Brooklyn's Downstate Medical Center discovered that hydrogen signal in cancerous tissue is different from that of healthy tissue because tumors contain more water. More water means more hydrogen atoms. When the MRI machine was switched off, the bath of radio waves from cancerous tissue will linger longer then those from the healthy tissue.

In 1973, Paul Lauterbur, a chemist and an NMR pioneer at the State University of New York, Stony Brook, produced the first NMR image.

Mike Goldsmith, one of the graduate students cobbled a wearable antenna coil to monitor the hydrogen broadcast detected by the coil.

On July 3, 1977, nearly five hours after the start of the first MRI test, the first human scan was made as the first MRI prototype.

Higher field strength scanners with a 1 - 1.5 Tesla (measurement of magnetic force) provide high resolutions, that is, clearer, easier to read scans. Open scanners usually have about a .23 Tesla. The higher the field strength, the more powerful and faster the scanner. As the field strength increases, the signal or ability to receive body images from the patient increases and results in a better quality image. MRI scanners scan the body in slices. On a high field or closed MRI system, the slice can be thinner, improving the image the physician uses to diagnose the problem. High field MRI systems also take less time due to the higher magnetic field strength. High field scans can be one and a half to two times faster than an "open" scan. As the scan time lengthens, the patient is more prone to movement, which reduces image quality. High field scanners also provide the most advanced imaging techniques, some of which cannot be performed on an "open" scanner.

There has been an increase in open MRI use due to the misunderstanding that closed scanners can be more claustrophobic for the patient. This misconception is, perhaps, caused by the design of each type of scanner. Traditional high field scanners are currently designed to increase patient comfort as well as reduce the anxiety that may occur with MRI patients. The newer scanners are designed with a substantially shorter bore or tube than the older scanners. This allows for the patient's head to be outside the bore of the magnet for a number of scans. The bore of the magnet is flared at the ends, so if a patient needs to be inside the scanner, the "closed in" feeling is reduced because the patient's head is towards a flared end. In addition, the bore has a larger width than that of the older scanners, which provides more room around the patient while inside the scanner.

Most MRI scanners have been designed with superior ventilation and lighting systems, allowing more air and light to circulate while scanning. Sometimes a patient can request changes in the ventilation and lighting if needed. Many MRI facilities provide music for patients to listen to during their scan for relaxation purposes.

In addition to the physical structure of the scanner reducing the anxiety of the patient, MRI technologists and support staff are experienced in dealing with patients who may be nervous. Most staff can comfort and relax patients, talk them through the scan and, if needed, sit with the patient and hold

By Rosalee L. Blumer
Senior Editor for MultipleSclerosis.com

Magnetic resonance imaging (MRI) techniques play an important role in the diagnosis of Multiple Sclerosis (MS). In addition to their role in diagnosis, MRI scans are also probably the best indicators of disease activity in relapsing forms of MS.

"In clinical practice, we use MRI to follow the MS disease process and to evaluate how somebody's doing on disease-modifying therapy," notes Patricia J. Coyle, MD, Director of the Stony Brook MS Comprehensive Care Center in New York. "MRI techniques, particularly the newer research techniques, may help us eventually figure out why MS occurs and how to prevent it."

An international panel of neurologists recently updated the existing guidelines for diagnosing MS, adding further importance to the role of MRI. The new criteria may allow an earlier diagnosis of MS than previous guidelines. Read more about the new guidelines

Eighty percent to 90 percent of MS brain lesions that show up on MRI scans do not seem related to clinical relapses. "This means MRI can detect ongoing disease activity of which people with MS and their physicians are not aware," Dr. Coyle points out.

MRI Techniques Commonly Used in MS

There are currently 3 conventional MRI techniques used in MS: T1, T2, and contrast, or gadolinium-enhanced, MRI.

On a T1 MRI scan, lesions are dark and appear as black or grey areas. Chronic lesions reflect damage caused by the loss of myelin and axons (nerve fibers). Sometimes referred to as "black holes," these lesions usually correlate with significant tissue destruction and disease-related disability, including cognitive impairment. The darker the lesion, the more extensive the damage, explains Dr. Coyle. However, the presence of a T1 lesion does not necessarily reflect permanent damage. Some studies have shown that a large number of T1 black holes may be reversible.

T2 MRI scans are useful for detecting MS lesions in the brain and, to a lesser extent, the spinal cord. These lesions appear as bright areas that resemble white, fluffy cotton balls. Neurologists can calculate the overall volume of the lesions on a T2 MRI to get a measure of the amount of brain tissue is involved in the disease process, says Dr. Coyle.

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