Branching Morphology of the Rat Hepatic Portal Vein Tree: A Micro-CT Study

Abstract

In contrast to the lung and the myocardium, the liver is a relatively homogeneous organ with fewer anatomic constraints on vascular branching. Hence, we hypothesize that the hepatic vasculature could more closely follow optimization of branching geometry than is the case in other organs. The geometrical and fractal properties of the rat hepatic portal vein tree were investigated, with the aid of three-dimensional micro-computed tomography data. Frequency distributions of vessel radii were obtained at three different voxel resolutions and fitted to a theoretical model of dichotomous branching. The model predicted an average junction exponent of 3.09. Hemodynamic model calculations showed that with generation, relative shear stress decreases. Branching angles were found to oscillate between those predicted by two optimality principles of minimum power loss and volume, and of minimum shear stress and surface. The liver shows a variation in branching morphology similar to that of other organs. Therefore, we conclude that anatomic constraints do not have a major perturbing impact.

Relating Function to Branching Geometry: A Micro-CT Study of the Hepatic Artery, Portal Vein, and Biliary Tree

“…Recent findings have shown morphological heterogeneity of the biliary epithelium, as well as a wide range of different pathophysiological responses by differentsized bile ducts [Glaser et al, 2006]. The strength of this study's method for measuring the junction exponent (as opposed to a minimization type approach [Op Den Buijs et al, 2006]) is that the collective behavior of the vascular tree's range of junction exponents can be determined while still including data in which one of the branch segments may be larger than the parent segment (in which case a minimization approach does not have a unique solution). The range of exponents found in the literature range from 1.0 up to 5.0 [Zamir et al, 1992], but most frequently lie between 2.0 and 3.0 [Kassab, 2006].…”

“…The main reason for this has been the methodological difficulties in obtaining accurate data, and in building a cumulative understanding based on these data. The measurement of length and diameter, and the connectivity relationship between interbranch segments lie at the foundation of most vascular geometry studies [Suwa et al, 1963;Zamir, 1998;Op Den Buijs et al, 2006;Kassab, 2006]. In a previous study, Kline et al [2010b] used optical measurement of the branches of intact casts of vascular trees as the gold standard, with each vascular segment mapped out and measured using micrometer translation and rotation.…”

Whole-Body Imaging of a Hypercholesterolemic Female Zebrafish by Using Synchrotron X-Ray Micro-CT

“…Therefore, applying the lCT system to hepatic biliary, arterial, and venous circulatory systems is difficult. 24,25 Considering that the synchrotron radiation lCT has a spatial resolution at the submicron level, it can be used to observe sinusoids and their alterations in 3D space. [26][27][28] In this study, the structural modifications in the sinusoids of the pathologically injured livers are detected through SR-lCT.…”

Three-dimensional observation of the mouse embryo by micro-computed tomography: composition of the trigeminal ganglion

“…Most information is stored not only in the form of direct anatomical or histological images but also as numerical information in 3D models following image processing. 11,12 For most soft tissue observations by micro-CT, however, a cast is fi rst made within the soft tissue space by using a CT-dense polymer. The cast structure is then observed indirectly.…”

“…The cast structure is then observed indirectly. 11,13 Three-dimensional studies of the embryo body, which is primarily composed of soft tissue, have mainly been performed by optical projection tomography (OPT), [14][15][16] and micro-CT has not yet been widely applied in this area.…”