2015 Volume 43 Issue 1 Pages 29-35
Meniere’s disease is essentially considered to be endolymphatic hydrops, but its etiology is unclear. For the future, we are planning to conduct studies of the pharmacokinetics of drugs used for the treatment of endolymphatic hydrops, such as isosobide dinitrate by serial MRI and, after the examination of MR images, proteomic molecular biological analysis using inner ear tissues before and after the administration of drugs. However, the complete genome sequence of guinea pigs, which have been used in past studies involving MRI, has not been clarified, and the use of humans for experiments is restricted. On the other hand, the complete genome sequence has been mapped in mice, and so it is useful for our planned molecular biological research. In this study, therefore, we prepared a system of measurement of the mouse’s inner ear using a 7.05 T MRI system. We administered a gadolinium contrast agent into the tympanic cavity to visualize the inner ear and examined the anatomical sites to which the contrast agent was transported and the time when contrast enhancement was maximized in 10 C57/B6J mice (♂: 21.5–33.3 g). After intraperitoneal anesthesia, a gadolinium contrast agent that had been diluted 8-fold with physiologic saline was administered into the tympanic cavity, and an MRI of the inner ear was performed under inhaled anesthesia using a mask. The gadolinium contrast agent was transported to the scala tympani and scala vestibule, which constitute the perilymphatic space, but not to the scala media, which is in the endolymphatic space, in any animal. Contrast of the tympanic cavity and perilymphatic space was enhanced in 8 (80%) of the 10 animals, excluding 2 that died, and contrast enhancement was maximized 2 hours after the administration of the contrast agent into the perilymphatic space in all 8 animals (100%).
