School of Information Technology and Mathematical Sciences, University of South Australia , Adelaide , Australia.
Cardiovascular Disease Program, Biosciences Discovery Institute and Department of Physiology, Monash University , Melbourne , Australia.
Am J Physiol Renal Physiol. 2018 May 1;314(5):F715-F725. doi: 10.1152/ajprenal.00339.2017. Epub 2017 Sep 20.
Vascular topology and morphology are critical in the regulation of blood flow and the transport of small solutes, including oxygen, carbon dioxide, nitric oxide, and hydrogen sulfide. Renal vascular morphology is particularly challenging, since many arterial walls are partially wrapped by the walls of veins. In the absence of a precise characterization of three-dimensional branching vascular geometry, accurate computational modeling of the intrarenal transport of small diffusible molecules is impossible. An enormous manual effort was required to achieve a relatively precise characterization of rat renal vascular geometry, highlighting the need for an automated method for analysis of branched vasculature morphology to allow characterization of the renal vascular geometry of other species, including humans. We present a semisupervised method for three-dimensional morphometric analysis of renal vasculature images generated by computed tomography. We derive quantitative vascular attributes important to mass transport between arteries, veins, and the renal tissue and present methods for their computation for a three-dimensional vascular geometry. To validate the algorithm, we compare automated vascular estimates with subjective manual measurements for a portion of rabbit kidney. Although increased image resolution can improve outcomes, our results demonstrate that the method can quantify the morphological characteristics of artery-vein pairs, comparing favorably with manual measurements. Similar to the rat, we show that rabbit artery-vein pairs become less intimate along the course of the renal vasculature, but the total wrapped mass transfer coefficient increases and then decreases. This new method will facilitate new quantitative physiological models describing the transport of small molecules within the kidney.
血管拓扑结构和形态在调节血流和小分子（包括氧气、二氧化碳、一氧化氮和硫化氢）的运输中起着关键作用。肾脏血管形态结构特别具有挑战性，因为许多动脉壁部分被静脉壁包裹。在缺乏对三维分支血管几何形状的精确描述的情况下，对肾脏内小分子扩散分子的输运进行准确的计算建模是不可能的。为了相对精确地描述大鼠肾脏血管几何形状，需要进行大量的手动工作，这突出表明需要一种用于分析分支血管形态的自动化方法，以允许对其他物种（包括人类）的肾脏血管几何形状进行特征描述。我们提出了一种用于计算机断层扫描生成的肾脏血管图像的三维形态计量分析的半监督方法。我们推导出了在动脉、静脉和肾脏组织之间进行质量传输的重要血管属性，并提出了用于计算三维血管几何形状的方法。为了验证该算法，我们将自动血管估计与兔肾的一部分的主观手动测量进行了比较。尽管增加图像分辨率可以改善结果，但我们的结果表明，该方法可以定量描述动脉-静脉对的形态特征，与手动测量相比具有优势。与大鼠类似，我们发现兔的动脉-静脉对在肾脏血管的过程中变得不那么密切，但总的包裹质量转移系数增加，然后减少。这种新方法将有助于建立新的定量生理模型，描述肾脏内小分子的运输。
