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18 Cards in this Set
- Front
- Back
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Differentiate demyelinating disease from small vessel ischemic changes
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1) Look for Dawson's fingers. The more linear the better.
2) Look for involvement of the optic nerves, optic pathways, corpus callosum, and U-fibers. |
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Best sequence on conventional MR to see gray matter lesions in MS?
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FLAIR
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Earliest sign of MS on conventional MR?
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Enhancement
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Then what?
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Then the high signal on FLAIR develops. Much harder to see on T2WI.
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Appearance of MS lesions on T1WI
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Most commonly they are isodense to white matter. But, if they are seen, it means one of 2 things. . . severe active lesion with a lot of edema or chronic burned out lesion with irreparable brain injury.
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How long does enhancement last?
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Days to weeks
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Appearance of enhancement in MS
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Start out as homogeneously enhancing lesions, and progress to ring enhancing lesions. Shape of lesion is variable though.
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Best method of assessing for active disease?
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LOOK FOR ENHANCING LESIONS. Lesion enhancement is much more sensitive indicator of active disease than clinical exam because most MS lesions are clinically silent.
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Affects ability to detect MS lesions
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Field strength
Gado dose -- Triple dose detects more lesions and increases size of enhancing areas. |
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Differential for bilateral thalamic pathology
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Infarct
Encephalitis Lymphoma or GBM |
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Infarcts specifically
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Arterial versus venous
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Arterial infarcts
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Determine based on which part of thalamus involved
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Anterior thalamus only
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Think basilar tip
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More of thalamus involved
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Think artery of Percheron
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What is artery of Percheron
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Arterial variant where single artery comes out of the basilar to supply much of the thalamus. If you have that variant, and it goes, you get screwed.
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Venous
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Deep venous system infarcts, like internal cerebral veins or vein of Galen.
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Type of encephalitis
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West Nile especially known for this
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Why lymphoma and GBM affect thalamus bilaterally
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They go across the massa intermedia (interthalamic adhesion) or habenula (posterior to interthalamic adhesion)
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