Fig. 4.

A 75-year old man with suspicion of endolymphatic hydrops. (a) Magnetic resonance cisternography indicates feather-like high signal intensity in the bilateral subinsular area, corresponding to the perivascular space (PVS) in white matter (WM) (black arrows). Dilated PVS in the basal ganglia (BG) can also be seen (short arrows). Sparsely distributed long PVSs in WM other than in the subinsular area are also visualized (arrows). (b) A heavily T₂-weighted 3D-fluid attenuated inversion recovery (FLAIR) image obtained prior to contrast administration. Although the PVSs in the subinsular WM show high signal intensity (black arrows), the PVSs in the BG do not. Sparsely distributed long PVSs in WM other than the subinsular area are also visualized as high signal intensity (arrows). (c) A heavily T₂-weighted 3D-FLAIR image obtained 4 h after contrast administration. The PVSs in the BG show apparent enhancement (short arrows). The CSF in the bilateral Sylvian fissures and other sulci is enhanced. Sparsely distributed long PVSs in WM other than in the subinsular area are also visualized as high signal intensity (arrows). The effect of contrast enhancement is not conspicuous in these long PVSs in WM as well as the PVSs in the subinsular WM (black arrows). The signal measurement of sparsely distributed long PVS is difficult due to their small diameter.