MR imaging of the cochlear modiolus after intratympanic administration of Gd-DTPA

Abstract

Purpose: We evaluated whether enhancement of the cochlear modiolus could be visualized 24 hours after intratympanic injection of gadolinium diethylenetriamine penta-acetic acid (Gd-DTPA) using a 3-dimensional real inversion recovery sequence combined with a 32-channel head coil at 3 tesla. Intratympanic injection of Gd-DTPA has been reported for visualizing endolymphatic hydrops in Meniere's disease, and its use has shown communication between the cochlear perilymph and cerebrospinal fluid in the internal auditory canal. Although the cochlear modiolus has been considered the route for this communication, this has not been confirmed through direct visualization of its enhancement. Materials and Methods: We qualitatively and quantitatively evaluated the presence of contrast enhancement in the modiolus in 19 patients with clinically suspected endolymphatic hydrops or hearing loss who underwent imaging as described above. Results: The contrast ratio (CR) between the cochlear modiolus and cerebellar white matter on the injected side was 1.09±1.23, and that on the non-injected side was -0.48±0.38 (P<0.01). In all subjects, the CR value was larger on the injected than non-injected side, and enhancement of the cochlear modiolus was also recognized visually. Conclusions: Intratympanic Gd-DTPA can be administered to visualize enhancement of the cochlear modiolus and may thereby reveal its functional anatomy.