An 80-year-old man with several years of orthostatic headaches but normal brain MR imaging findings (not shown). Representative image from a left lateral decubitus DSM centered at T10 (A) shows a small meningeal diverticulum (A, dashed arrow) but no evidence of a CVF. Axial 40-keV images at 2 adjacent slices from a left lateral decubitus PCD CTM (B and D) demonstrate opacification of a paraspinal vein (B, arrow) and the azygous and hemiazygous vein (D, arrow), consistent with a CVF. Axial 40-keV images at the same slices obtained 30 seconds later (C and E) no longer show contrast within these veins (C and E, arrows). The patient underwent transvenous Onyx embolization of the left T10 CVF.