An 35 year old man presented with headache and confusion following a motor vehicle accident.
Axial MRI scans: (Left) T1-weighted; (Right) T2-weighted. Note on T1, there is an abnormality that is mostly isointense in the right frontal pole. Looking closely, there is some hypointensity inferiorly and some hyperintensity superiorly. The same area on T2 is dark with a surrounding bright signal. The dark signal on T1 and T2 represents deoxyhemoglobin whereas the isotense signal is oxyhemoglobin. The surrounding bright signal is vasogenic edema. The slight hyperintense signal on T1 is the early transition of some the hematoma to intracellular methemoglobin.
This is the characteristic picture of an hyperacute hemorrhage changing to an acute (approximately 3 days old) hemorrhage on MRI. 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.
On the left side, there is edema in the frontal pole (dark on T1 and bright on T2).
Revised
05/02/06.
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