Noninvasive evaluation of endolymphatic space in healthy volunteers using magnetic resonance imaging

A new method for noninvasive standard evaluation of normal endolymphatic space and endolymphatic hydrops using magnetic resonance imaging (MRI) is indicated.

To standardize the evaluation of endolymphatic space in the cochlea and the vestibule in healthy volunteers by applying noninvasive intratympanic gadolinium (Gd) perfusion through the eustachian tube and three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI).

This was a prospective study. 3D-FLAIR MRI was performed with a 3 Tesla (3 T) unit 24 h after intratympanic administration of Gd through the eustachian tube in 20 healthy volunteers. Pure tone test and tympanometry were performed 24 h before Gd was administered, and 24 h and 1 month after Gd administration.

Gd was present in the perilymph of the inner ear, which clearly displayed the endolymphatic space on 3D-FLAIR MRI with a visible borderline between the perilymph and the endolymph. In healthy volunteers, the normal value for the endolymphatic space in the cochlea ranged between 9% and 28%, and that in the vestibule was between 14% and 40%. No significant changes in pure tone test and tympanometry were noted.