Читать книгу Vestibular Disorders - Группа авторов - Страница 35

In CT, the cochlear partition and soft tissue as membranes are not adequately visualized [10, 11]. The gray levels in a CT slice image correspond to X-ray attenuation, which reflects the proportion of X-rays scattered or absorbed as they pass through each voxel, and is affected by the density and composition of the material being imaged. Non-destructive X-ray μCT has proven its utility in 3D assessment of mineralized and soft tissue morphology [133, 134]. The cochlear partition and the basilar membrane could not be distinguished and reconstructed with µCT [134]. Recently, Poznyakovskiy et al. [135] presented an algorithm for cochlear segmentation, which resulted in the reconstruction of scala tympani. µCT has been engaged in middle and inner ear imaging of animals and implicated to be a useful tool to trace the distribution of drugs in the inner ear. However, it can only be used for ex vivo imaging due to the extremely high dose of exposure and the close imaging distance which is only suitable for the head [136]. The contrast-enhanced μCT methodology is further developed for ex vivo cochlear imaging [28]. It can demonstrate the position of Reissner’s membrane and basilar membrane if a contrast agent is used [136]. Figure 8 demonstrates CI electrode imaged with μCT. However, μCT produces extremely high radiation dose and in present form cannot be applied in humans.

Recently, this technique has been advanced in animal experiments by revealing the inner ear compartment with simultaneous 9T MRI scanner and μCT [2]. The combined MRI-µCT imaging techniques were complementary, and provided high-resolution dynamic and static visualization of the morphological features of the normal mouse inner ear structures.

Fig. 8. Imaging of CI electrode with µCT, a shows the basal electrodes stimulating areas close to the round window, b shows the first and second tip electrodes aimed to stimulate the apex of the cochlea.