*Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto; †Adachi ENT Clinic, Kobe; and ‡Department of Otolaryngology, Tenri Hospital, Tenri, Japan.
Otol Neurotol. 2014 Feb;35(2):e84-9. doi: 10.1097/MAO.0000000000000252.
Cochlear pathology can be evaluated in living animals using optical coherence tomography (OCT).
The current imaging methods available for the detailed analysis of cochlear pathology in a clinical setting provide only limited information. Thus, a cochlear imaging modality with high definition is needed for improving the diagnosis of cochlear pathology. OCT has been used in other fields for obtaining high-resolution subsurface images, and its use could potentially be extended to the analysis of cochlear pathogenesis.
Slc26a4(-/-) mice, which generate endolymphatic hydrops, and their littermates were used in this study. Auditory function was monitored by the auditory brainstem responses (ABR). After the mice were placed under general anesthesia, OCT images of the cochlea were captured. The cochlea was subsequently dissected out and histologically evaluated. Three or 7 days later, the wild-type mice cochleae were visualized again.
In ABR assessments, Slc26a4(-/-) mice showed severe hearing loss, while no significant hearing loss was found in Slc26a4(+/-) or Slc26a4(+/+) mice. OCT demonstrated normal morphology in the cochlea of both Slc26a4(+/-) and Slc26a4(+/+) mice, including the location of Reissner's membrane. Meanwhile, in Slc26a4(-/-) mice, obvious dislocation of Reissner's membrane was observed, indicating severe endolymphatic hydrops. These findings in the OCT images were consistent with the histologic results for the cochlear morphology, as observed with hematoxylin and eosin staining. Three or 7 days later, wild-type cochleae were successfully visualized using OCT, and no otitis media or labyrinthitis was observed.
OCT can be applied in the detection of endolymphatic hydrops in living mice, indicating the potential of OCT for cochlear imaging analyses for clinical use in the near future.
可以使用光相干断层扫描（OCT）在活体动物中评估耳蜗病理学。
目前在临床环境中用于详细分析耳蜗病理学的现有成像方法仅提供有限的信息。因此，需要一种具有高清晰度的耳蜗成像方式来改善耳蜗病理学的诊断。OCT 已在其他领域用于获得高分辨率的亚表面图像，并且其用途有可能扩展到耳蜗发病机制的分析。
本研究使用产生内淋巴积水的 Slc26a4(-/-) 小鼠及其同窝仔鼠。通过听觉脑干反应（ABR）监测听觉功能。将小鼠置于全身麻醉下后，捕获耳蜗的 OCT 图像。随后将耳蜗取出并进行组织学评估。3 或 7 天后，再次观察野生型小鼠的耳蜗。
在 ABR 评估中，Slc26a4(-/-) 小鼠表现出严重的听力损失，而 Slc26a4(+/-)或 Slc26a4(+/+)小鼠则没有明显的听力损失。OCT 显示 Slc26a4(+/-)和 Slc26a4(+/+)小鼠的耳蜗形态正常，包括 Reissner 膜的位置。同时，在 Slc26a4(-/-)小鼠中，观察到 Reissner 膜明显脱位，表明严重的内淋巴积水。OCT 图像中的这些发现与耳蜗形态的苏木精和伊红染色组织学结果一致。3 或 7 天后，成功使用 OCT 可视化野生型耳蜗，并且未观察到中耳炎或迷路炎。
OCT 可用于检测活体小鼠中的内淋巴积水，表明 OCT 具有用于耳蜗成像分析的潜力，有望在不久的将来用于临床。
