Counter S Allen, Damberg Peter, Aski Sahar Nikkhou, Nagy Kálmán, Berglin Cecilia Engmér, Laurell Göran
Neurology Department, Harvard University Biological Laboratories, Cambridge, MA 02138, USA.
Karolinska Experimental Research Imaging Center, Karolinska Universitetssjukhuset Solna, Sweden.
Open Neuroimag J. 2015 Jul 31;9:7-12. doi: 10.2174/1874440001509010007. eCollection 2015.
Imaging cochlear, vestibular, and 8th cranial nerve abnormalities remains a challenge. In this study, the membranous and osseous labyrinths of the wild type mouse inner ear were examined using volumetric data from ultra high-field magnetic resonance imaging (MRI) with gadolinium contrast at 9.4 Tesla and high-resolution micro-computed tomography (µCT) to visualize the scalae and vestibular apparatus, and to establish imaging protocols and parameters for comparative analysis of the normal and mutant mouse inner ear.
For in vivo MRI acquisition, animals were placed in a Milleped coil situated in the isocenter of a horizontal 9.4 T Varian magnet. For µCT examination, cone beam scans were performed ex vivo following MRI using the µCT component of a nanoScan PET/CT in vivo scanner.
The fusion of Gd enhanced high field MRI and high-resolution µCT scans revealed the dynamic membranous labyrinth of the perilymphatic fluid filled scala tympani and scala vestibule of the cochlea, and semicircular canals of the vestibular apparatus, within the µCT visualized contours of the contiguous osseous labyrinth. The ex vivo µCT segmentation revealed the surface contours and structural morphology of each cochlea turn and the semicircular canals in 3 planes.
The fusion of ultra high-field MRI and high-resolution µCT imaging techniques were complementary, and provided high-resolution dynamic and static visualization of the complex morphological features of the normal mouse inner ear structures, which may offer a valuable approach for the investigation of cochlear and vestibular abnormalities that are associated with birth defects related to genetic inner ear disorders in humans.
对耳蜗、前庭及第八颅神经异常进行成像仍是一项挑战。在本研究中，利用9.4特斯拉超高场磁共振成像（MRI）加钆对比剂的容积数据以及高分辨率微型计算机断层扫描（µCT），对野生型小鼠内耳的膜迷路和骨迷路进行检查，以可视化蜗管和前庭装置，并建立成像方案和参数，用于正常和突变小鼠内耳的对比分析。
对于体内MRI采集，将动物置于位于水平9.4 T瓦里安磁体等中心的千足虫线圈中。对于µCT检查，在MRI后使用体内扫描仪nanoScan PET/CT的µCT组件进行离体锥束扫描。
钆增强高场MRI与高分辨率µCT扫描的融合显示，在µCT可视化的相邻骨迷路轮廓内，充满外淋巴液的蜗管鼓阶和蜗管前庭以及前庭装置的半规管的动态膜迷路。离体µCT分割显示了每个耳蜗旋转和三个平面中的半规管的表面轮廓和结构形态。
超高场MRI和高分辨率µCT成像技术的融合具有互补性，可对正常小鼠内耳结构的复杂形态特征进行高分辨率动态和静态可视化，这可能为研究与人类遗传性内耳疾病相关的出生缺陷所导致的耳蜗和前庭异常提供一种有价值的方法。
