Figure 6a. Dural sinus thrombosis in a 20-year-old woman with a 2-week history of worsening headache. (a) Unenhanced axial CT image shows increased attenuation in the superior sagittal sinus (straight arrow) and straight sinus (curved arrow), findings consistent with thrombosis. (b) Unenhanced sagittal MR image shows replacement of the flow void of the superior sagittal sinus by intermediate signal intensity (arrows), which indicates thrombosis. (c) Contrast-enhanced axial MR image shows absence of the flow void in the superior sagittal sinus (straight arrow) and straight sinus (curved arrow) with mild enhancement of the periphery of the thrombus. (Courtesy of D. James Schumacher, MD, Cape Canaveral Hospital, Melbourne, Fla.)