Observation of the mouse vestibule by 7.05 Tesla MRI after the intratympanic administration of gadolinium

Abstract

Introduction : We previously studied the mouse inner ear by 7.05 Tesla (T) MRI after the intratympanic administration of gadolinium. The appearance of the endolymphatic space (ES) in the cochlea is similar to the pathological appearance, and cochlear endolymphatic hydrops could thus be detected. However, we had not previously detected the ES in the vestibule. The aim of this study was to visualize the ES in the mouse vestibule using MRI. Materials and methods : The vestibular structures of 56 C57BL/6 mice were visualized using 7.05T MRI at 1-2 hours after the intratympanic injection of gadolinium contrast media. We observed the ES on the modiolar plane. We counted both the pixel counts of the ES and the vestibular space on the plane in which the ES showed its maximum diameter. The ES ratio, which was defined as the pixel count of the ES divided by the pixel count of the vestibular space was measured in each case. Results : The ES was visualized in all ears. The mean ES ratio was 0.419 ± 0.05 and the median ES ratio was 0.420. Conclusion : The living mouse ES could be accurately visualized by MRI. This method could visualize morphological changes in the ES of model animals with endolymphatic hydrops and therefore is considered to be useful for investigating the cause of vertigo attacks in patients with Meniere's disease.