Morphological and functional properties of the conducting human airways investigated by in vivo computed tomography and in vitro MRI.
Morphological and functional properties of the conducting human airways investigated by in vivo computed tomography and in vitro MRI.
复制标题
通过体内计算机断层扫描和体外 MRI 研究人类传导气道的形态和功能特性。
DOI：
10.1152/japplphysiol.00490.2017
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Coletti,Filippo
中科院分区：
文献类型：
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作者：
VandeMoortele,Tristan;Wendt,ChristineH;Coletti,Filippo
人体气道解剖结构的准确表示对于理解和建模健康和患病肺的结构-功能关系至关重要。目前在这方面的知识是基于切除的肺管型的形态学研究，部分补充了体内研究，其中计算机断层扫描（CT）被用于少数受试者。在本研究中，我们分析了一组健康受试者的CT扫描，并获得了第七代支气管分支的全面形态测量信息，包括气道直径、长度、分支角度和旋转角度。虽然一些几何参数（如子-父分支直径比）被认为是符合公认的值，对于其他（如分支长度-直径比），我们的研究结果挑战的共同假设。我们还评估了自相似性的几个指标，包括气道树的分形维数。此外，我们使用相衬磁共振成像（MRI），以获得稳定吸入过程中的一个受试者的三维打印气道模型中的体积流场。这用于关联结构和功能参数，特别是闭合分支流速和直径之间的幂律关系。发现直径指数显著低于通常假设的Poiffille区域，我们将其归因于强次级（即，横向）速度分量。二次速度相对于轴向分量的强度超过了理想化气道模型中发现的水平，并持续在前七代。新&值得注意的是，我们进行了一个全面的计算机断层扫描为基础的研究正常人受试者的传导气道形态，包括分支直径，长度和相互角度。我们发现了与经典的位似关系的显著偏离。我们还进行了MRI测量的三维吸气流的解剖为基础的模型，并直接评估结构功能的关系，到目前为止已经假设。我们发现，强大的二次流（即，横向速度分量）持续通过支气管分支的前七代。
The accurate representation of the human airway anatomy is crucial for understanding and modeling the structure-function relationship in both healthy and diseased lungs. The present knowledge in this area is based on morphometric studies of excised lung casts, partially complemented by in vivo studies in which computed tomography (CT) was used on a small number of subjects. In the present study, we analyzed CT scans of a cohort of healthy subjects and obtained comprehensive morphometric information down to the seventh generation of bronchial branching, including airway diameter, length, branching angle, and rotation angle. Although some of the geometric parameters (such as the child-to-parent branch diameter ratio) are found to be in line with accepted values, for others (such as the branch length-to-diameter ratio) our findings challenge the common assumptions. We also evaluated several metrics of self-similarity, including the fractal dimension of the airway tree. Additionally, we used phase-contrast magnetic resonance imaging (MRI) to obtain the volumetric flow field in the three-dimensional-printed airway model of one of the subjects during steady inhalation. This is used to relate structural and functional parameters and, in particular, to close the power-law relationship between branch flow rate and diameter. The diameter exponent is found to be significantly lower than in the usually assumed Poiseuille regime, which we attribute to the strong secondary (i.e., transverse) velocity component. The strength of the secondary velocity with respect to the axial component exceeds the levels found in idealized airway models and persists within the first seven generations.NEW & NOTEWORTHYWe performed a comprehensive computed tomography-based study of the conductive airway morphology in normal human subjects, including branch diameter, length, and mutual angles. We found significant departure from classic homothetic relationships. We also carried out MRI measurements of the three-dimensional inspiratory flow in an anatomy-based model and directly assessed structure-function relationships that have so far been assumed. We found that strong secondary flows (i.e., transverse velocity components) persist through the first seven generations of bronchial branching.