FIG 1. Images reveal arachnoid granulation in a 37-year-old man with postoperative changes of a right temporal lobe oligodendroglioma.

A, 3D contrast-enhanced MPRAGE image (13.5/7/1; inversion time, 300 ms; flip angle, 15 degrees) shows a well-circumscribed, round, hypointense focal filling defect (arrowheads) within the right transverse sinus.

B, Axial T2-weighted MR image (3700/96) shows that the structure shown in A (arrowheads) is isointense to CSF.

C, Unenhanced T1-weighted MR image (627/17) shows that the structure shown in A and B is also isointense to CSF in this image.