The purpose of the present work is to establish a basic knowledge about the scaling properties of the placenta's arterial tree. For this end we have analysed X-ray angiograms of 22 normal arterial trees by box counting. All the investigated arterial trees scale closely according to a power-law over
On Fractal Properties of Arterial Trees
โ Scribed by M. Zamir
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 183 KB
- Volume
- 197
- Category
- Article
- ISSN
- 0022-5193
No coin nor oath required. For personal study only.
โฆ Synopsis
The question of fractal properties of arterial trees is considered in light of data from the extensive tree structure of the right coronary artery of a human heart. Because of the highly non-uniform structure of this tree, the study focuses on the purely geometrical rather than statistical aspects of fractal properties. The large number of arterial bifurcations comprising the tree were found to have a mixed degree of asymmetry at all levels of the tree, including the depth of the tree where it has been generally supposed that they would be symmetrical. Cross-sectional area ratios of daughter to parent vessels were also found to be highly mixed at all levels, having values both above and below 1.0, rather than consistently above as has been generally supposed in the past. Calculated values of the power law index which describes the theoretical relation between the diameters of the three vessel segments at an arterial bifurcation were found to range far beyond the two values associated with the cube and square laws, and not clearly favoring one or the other. On the whole the tree structure was found to have what we have termed ''pseudo-fractal'' properties, in the sense that vessels of different calibers displayed the same branching pattern but with a range of values of the branching parameters. The results suggest that a higher degree of fractal character, one in which the branching parameters are constant throughout the tree structure, is unlikely to be attained in non-uniform vascular structures.
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