Large vestibular aqueduct with large endolymphatic duct and sac.
This 5-year-old child was evaluated for sensorineural hearing loss. A. An axial 3D T2-weighted steady-state free-precession (TRUFI) MR image shows dilation of the endolymphatic duct and sac (arrows). B. This image is 9mm inferior to (A). The dilated endolymphatic sac (arrow) is adjacent to the surface of the cerebellum and medial to the sigmoid sinus. (Images courtesy of Brian Lundeen, M.D., Pediatric Diagnostic Imaging, Milwaukee, WI)