Navigation System through Bronchiolo-Alveolar Space by Virtual Microscopic Bronchoscopy based on Three Dimensional Coned-Beam Micro CT Data

了解肺的细支气管-肺泡结构在肺部疾病的临床诊断中很重要。本研究基于三维锥束显微CT数据，通过虚拟支气管镜显示和导航来了解周围呼吸道的三维结构。材料和方法：手术切除的肺叶按照Heitzman的方法进行充气和化学固定。用岛津SMX-225型微型聚焦锥束CT系统采集充气和固定肺标本的三维CT数据。扫描参数：-512x512~1024x1024像素-40~50kV，30μA-FOV：2.7~12.1 mm-层厚：5.4~6.8微米。获取体积数据，利用作者之一(K.M.)开发的NewVES查看器重建三维图像。结果：微聚焦锥束CT成功导航到细支气管、呼吸性细支气管、肺泡管和肺泡。获得了肺泡水平的空间分辨率。体积成像显示小叶中央部可见细支气管区及伴行小动脉。小叶之间可见小静脉和间隔。确定了小气道和肺泡的三维结构。通过NewVES查看器的导航功能，观察者体验了从细支气管端到肺泡的虚拟显微导航。结论：这种三维显示方法似乎有助于了解周围肺的微观解剖结构。该方法可用于对呼吸道的非破坏性三维了解。重复的无限制导航是可能的。锥束微聚焦CT容积再现技术的显微仿真支气管镜检查有望成为下一代的诊断手段。

Knowledge of the bronchiolo-alveolar structures of the lung is important in the clinical diagnosis of pulmonary diseases. This study was performed to understand the three-dimensional architecture of peripheral airways by virtual bronchoscopic presentation and navigation based on three dimensional coned-beam micro CT data. Also, the usefulness of this microscopic virtual navigation system in the peripheral lung structure was evaluated1,2,3).Materials and Methods:A surgically resected pulmonary lobe was inflated and chemically fixed according to Heitzman's method4). 3-D CT data of the inflated and fixed lung specimens was obtained by Shimadzu micro-focused cone-beam CT system type SMX-225CT. Scan parameters are as follows:-512x512〜1024x1024 pixels-40〜50 kV, 30μA-FOV: 2.7〜12.1mm-Slice thickness : 5.4〜6.8 micrometerThe volumetric data are obtained, and 3-D images are reconstructed by the NewVES viewer created by one of the authors (K.M.)5).Results:Navigation to the bronchioles, respiratory bronchioles, alveolar ducts, and alveoli were made successfully by micro-focused cone-beam CT. Spatial resolution of the level of alveoli was obtained. Bronchioles and accompanied arterioles were found in the central portion of the lobules by the volume rendering mode. Venules and septa were found between the lobules. 3-D structures of the small airways and alveoli were identified. Observers experienced virtual microscopic navigations through terminal bronchioles to alveoli by the navigation function of the NewVES viewer6-9).Conclusion:The 3-D displaying method seems to be useful to understand microscopic anatomical structures of the peripheral lung. This method was useful for non-destructive three dimensional understanding of airways. Repeated non-limited navigation was possible. The microscopic virtual bronchoscopy by the volume rendering method by coned-beam micro-focused CT could be developed as a diagnostic method of the next generation.