Title: Shades of Gray Matter - Brain MRI 101<br/>Author: WanTsu Wendy Chang<br/><a href='http://umem.org/profiles/faculty/1322/'>[Click to email author]</a><hr/><div>
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<strong>Shades of Gray Matter - Brain MRI 101</strong></div>
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Want to learn more about how to read a brain MRI? Here are the basics:</p>
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MRIs are described by signal intensity, as compared to CTs where lesions are described by density.
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A dark lesion on MRI is “hypointense”</li>
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A bright lesion on MRI is “hyperintense"</li>
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The most commonly used MRI sequences are T1-weighted, T2-weighted, FLAIR, and Diffusion-weighted.
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<u>T1</u>-weighted images are good for <u>brain parenchyma</u>.
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Contrast enhanced T1 with gadolinium helps differentiate pathological tissue (e.g. tumors, inflammation, infection)</li>
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<u>T2</u>-weighted images are good for <u>CSF spaces and periventricular white matter</u>.
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Edema from a tumor, subacute stroke or hemorrhage appears bright</li>
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Periventricular white matter scarring from multiple sclerosis appears bright</li>
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<u>FLAIR</u> images are T2 images where CSF is dark. FLAIR is very sensitive to <u>edema and parenchymal lesions</u>.</li>
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<u>Diffusion</u>-weighted sequences are good for <u>cellular swelling</u>.
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<b>Acute ischemia</b> appears <b>bright</b> on <u>Diffusion-Weighted Imaging</u> (DWI) and <b>dark</b> on <u>Apparent Diffusion Coefficient</u> (ADC) maps</li>
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<i>Some neoplasms, abscesses and toxic/metabolic/demyelinating processes can also appear bright on DWI.</i></li>
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Stay tuned for more pearls in this series on brain MRI!</p>
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