A 63 year old man presented with headache and progressive numbness affecting the right arm which slowly progressed over several hours.
Axial MRI scans: (Left) T1-weighted; (Right) T2-weighted. Note on T1, there is an area of hyperintense signal in the left parietal lobe. The same area on T2 is dark with a surrounding bright signal. This is the characteristic picture of a subacute early (3-7 days) hemorrhage on MRI. The hyperintense signal on T1 with the hypointense signal on T2 is is the pattern seen with intracellular methemoglobin. The bright surrounding signal on T2 is vasogenic edema. The findings of blood on MRI are complex and depend on timing. To learn more, review the powerpoint slide show, Blood on MRI: Time-dependent Changes. In this case, the hemorrhage was due to hypertension.
Revised05/02/06.
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