3-D display of the peripheral microstructure of the lung with synchrotron radiation CT

【目的】由于CT的空间分辨率（即使是高分辨率CT也只有300微米）的限制，肺的三维显微结构（呼吸细支气管以外的周围结构）非常难以可视化。在这项研究中，我们尝试使用肺标本的同步辐射CT （SRCT）体积数据来可视化肺周围微结构的三维显示。【材料与方法】尸检时取正常肺及几种病变肺标本，用Heitzman方法充气固定。每个试样被切割成直径6毫米，高20毫米的圆柱形试样。利用同步辐射设施（Super Photon Ring 8.0 GeV, Hyogo, Japan）构建的SRCT系统获得样品的SRCT图像。SRCT提供各向同性的体积数据（空间分辨率12微米），有815个序列切片，每个切片有800 x 800像素。在工作站（Sun SPARCstation）上，采用自动分割和表面与体绘制显示技术相结合的方法构建三维微结构，并对空气进入周边气道和空气空间的多个三维气流模型进行动画显示。[结果]准确建立了肺外周显微结构的三维显示。外围气流的三维模型可以表示“气流”和“扩散”。末梢细支气管与末梢细支气管之间的传导部位在气道内最窄。下一个外周部分扩展到分支到第二呼吸细支气管。【结论】同步辐射CT三维显示外周肺结构和三维外周气流模型，使我们能够无损地研究外周呼吸系统的形态、生理和病理生理。

[Purpose] 3-D microstructure of the lung (peripheral structures beyond respiratory bronchiole) is extremely difficult to visualize, because of the limitation of spatial resolution of CT (300 micrometer even with high resolution CT). In this study, we try to visualize 3-D display of the peripheral microstructures of the lung using the volume data with synchrotron radiation CT (SRCT) of the lung specimen.[Materials and Methods] Lung specimens of normal lung and several disease processes were obtained at autopsy, and were inflated and fixed by Heitzman's method. Each specimen was cut down to cylindrical sample specimen with 6-mm diameter and 20 mm height. SRCT images of the sample specimens were obtained with SRCT system constructed at synchrotron radiation facility (Super Photon Ring 8.0 GeV, Hyogo, Japan). SRCT provides isotropic volume data (spatial resolution 12 micrometer), with serial 815 slices and each slice with 800 x 800 pixels. 3-D microstructures were constructed with automatic segmentation and combination of the surface and volume rendering display technique on the workstation (Sun SPARCstation), Several 3-D models of the air flow could be illustrated with animation as air came into the peripheral airway and air space.[Results] 3-D display of the peripheral microstructure of the lung was established precisely. 3-D models of the peripheral airflow could represent "airflow" and "diffusion". Conducting parts between terminal bronchiole and peripheral bronchiole were narrowest in the airway. The next peripheral portions were expanded to branch to second respiratory bronchioles.[Conclusion] 3-D display of the peripheral pulmonary structure and 3-D models of the peripheral air flow with synchrotron radiation CT enable us to study the morphology, physiology, and pathophysiology of the peripheral respiratory system non-destructively.