Shadow sign in a T2* brain image in spontaneous middle cerebral artery dissection.

A29-year-old man presented with unilateral dull headache for 3 days, similar to previous headache, but with right hemiparesis; there was no antecedent infection or trauma. MRI showed left striatocapsular infarction (figure 1A), without evidence of cardioembolism or vasculitis. Digital subtraction angiography demonstrated stenosis of the left middle cerebral artery (MCA) trunk (figure 1B). Intramural hematoma suggests arterial dissection. The bulging intramural hematoma seen on T2* corresponded with an eccentric high signal rim on sagittal T1-weighted imaging, along the anterosuperior MCA wall at the arterial perforator origin (figure 2). The diagnosis was spontaneous MCA dissection.