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Magnetic
Resonance (MR or MRI) is the preferred method of imaging the brain to detect the
presence of plaques or scarring caused by multiple sclerosis (MS). Due to the excellent
tissue contrast of MR, it is better at detecting plaques than computed
tomography (CT or CAT scanning). Often, brains that appear to be normal on CT images
will be shown to have MS plaques on MR images.
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| Axial T2
weighted MR image, bright CSF obscures the MS plaque in this brain, even using high
resolution matrix |
Fluid-suppressed
"Turbo FLAIR" MR image, the bright MS plaque is now apparent. Images courtesy of
Siemens Medical Solutions (http://www.usa.siemens.com/) |
MR became clinically available in the
mid-1980s. Traditionally, a "T2" MR image of the brain was used to show MS
lesions (areas of damage or disease) and to diagnose multiple sclerosis. T2 MR images show
brain tissue as dark and cerebrospinal fluid (CSF) as bright. MS lesions are also show as
bright areas or spots on T2 images. In some cases, the bright CSF fluid made the
identification of MS plaques difficult on standard T2 images. However, newer MR techniques
(sequences) called "dark fluid" or "Turbo FLAIR" have been developed
to suppress the bright CSF on T2 images so that the MS plaques are more evident. These
"fluid suppressed T2" sequences are available on advanced MR systems. These
sequences can be performed at various magnetic field strengths including lower field
strength magnets used with "Open MR" systems.
MS diagnosis with advanced Open MR system, image courtesy of Siemens Medical Solutions (http://www.usa.siemens.com/). T2 image on the
left and Turbo-FLAIR image on the right.
The diagnosis of MS cannot be made
solely on the basis of MR imaging. There are other neurologic diseases such as Glioma that
cause lesions in the brain that appear similar to MS plaques on MR images. There are also
abnormalities found in healthy individuals, particularly in older persons, that are not
related to any ongoing disease process.
On the other hand, a normal MR does not
absolutely rule out a diagnosis of MS. Approximately five percent of patients who are
confirmed to have multiple sclerosis on the basis of other criteria, do not show any
plaques or lesions in the brain on MR images. These people may have lesions in the spinal
cord or may have plaques that cannot be detected by MR imaging.
Updated: July 23, 2007
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