tara97 wrote:what does it mean when you have a demylinating lession that does not contrast. I know that means its not ms definitive but what is the difference between lessions that contrast and ones that dont?
The "classic" old, scarred, mature MS lesion or plaque is somewhat oval in shape, will have well-defined borders and will appear in the white matter. The "classic" MS lesion will also have its long axis perpendicular to the ventricles (the large fluid-filled spaces) of the brain. Characteristic places (but not the only places) are peri-ventricular, juxtacortical, the corpus callosum, the cerebellum and the cervical spine. Also, important and often very symptomatic lesions are found in the brainstem and the thoracic spine. The spinal cord ends at the bottom of the thoracic spine, so there is no such thing as a lumbar spinal cord lesion. The scarred lesions will be evident as light, bright (hyperintense) areas on the T2 images. These are the classic MS lesions or "plaques." But, with just the regular MRI image one CANNOT say if it is old and dormant or if it has active inflammation in or around it.
The Need For Contrast
For the most part all visible lesions can be seen without contrast. They show up as T2 Hyperintensities just like all lesions. The problem is that the neurologist can't tell if a lesion is old or new. So new activity will be missed and the MRI may be erroneously dismissed as "unchanged" or "no progression." In the inflammation of new lesions there is a breach in the blood-brain barrier. Wherever there is a break in the blood-brain barrier, the contrast will leak into the brain tissue and the areas will "highlight" or "enhance." They show up as even brighter than the brain around them and brighter than an old, scarred lesion. So new lesions will appear as "enhancing," or "active." Also, older hyperintense lesions that have undergone a new attack at their adges or margins. This is also called reactivation. Lesions that have reactivated may show an even brighter enhancing rim or ring.
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