BACKGROUND Understanding airflow through human airways is of importance in drug delivery and development of assisted breathing methods. In this work, we focus on development of a new method to obtain an averaged upper airway geometry from computed tomography (CT) scans of many individuals. This geometry can be used for air flow simulation. We examine the geometry resulting from a data set consisting of 26 airway scans. The methods used to achieve this include nasal cavity segmentation and a deformable template matching procedure. METHODS The method uses CT scans of the nasal cavity of individuals to obtain a segmented mesh, and coronal cross-sections of this segmented mesh are taken. The cross-sections are processed to extract the nasal cavity, and then thinned ('skeletonized') representations of the airways are computed. A reference template is then deformed such that it lies on this thinned representation. The average of these deformations is used to obtain the average geometry. Our procedure tolerates a wider variety of nasal cavity geometries than earlier methods. RESULTS To assess the averaging method, key landmark points on each of the input scans as well as the output average geometry are located and compared with one another, showing good agreement. In addition, the cross-sectional area (CSA) profile of the nasal cavities of the input scans and average geometry are also computed, showing that the CSA of the average model falls within the variation of the population. CONCLUSIONS The use of a deformable template method for aligning and averaging the nasal cavity provides an improved, detailed geometry that is unavailable without using deformation.

中文翻译：

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用于描述和平均人鼻腔解剖变化的可变形模板方法。

背景技术了解通过人类呼吸道的气流在药物输送和辅助呼吸方法的开发中很重要。在这项工作中，我们致力于开发一种新方法，以从许多个人的计算机断层扫描（CT）扫描中获得平均上呼吸道几何形状。此几何可用于气流模拟。我们检查了由26次气道扫描组成的数据集所产生的几何形状。用于实现此目的的方法包括鼻腔分割和可变形模板匹配程序。方法该方法利用个人鼻腔的CT扫描获得分割的网片，并对该分割网片的冠状横截面进行拍摄。处理横截面以提取鼻腔，然后计算气道的细化（“骨骼化”）表示。然后，将参考模板变形，使其位于此稀疏表示上。这些变形的平均值用于获得平均几何形状。与早期方法相比，我们的程序可耐受的鼻腔几何形状范围更广。结果为了评估平均方法，对每个输入扫描的关键界标点以及输出平均几何形状进行了定位并进行了比较，显示出很好的一致性。此外，还计算了输入扫描的鼻腔的横截面积（CSA）轮廓和平均几何形状，这表明平均模型的CSA属于总体变化范围。结论使用可变形模板方法对准和平均鼻腔可提供一种改进的，详细的几何形状，而在不使用变形的情况下是无法获得的。