Fig 3.

Images reveal arachnoid granulations in a 54-year-old man with headaches who had normal results of an MR imaging study.

A, Sagittal reconstruction image obtained from 3D contrast-enhanced MPRAGE imaging sequence shows a large CSF-isointense filling defect, consistent with an arachnoid granulation (black arrows), at the junction point of the vein of Galen and straight sinus. Note also the presence of smaller arachnoid granulations within the superior sagittal sinus (white arrowheads).

B, Axial T2-weighted MR image shows the defect seen in A as a discrete, focal CSF-isointense filling defect within the straight sinus.