Structural quantification and bifurcation symmetry in arterial tree models generated by constrained constructive optimization.

Arterial tree models are generated by Constrained Constructive Optimization according to minimum intravascular volume. These models, which have been shown to adequately reproduce pressure profiles and branching angles, are analysed topologically and geometrically in order to investigate how structure influences the functional capabilities. Therefore, the number of bifurcation levels and STRAHLER orders was evaluated for the complete trees as well as for subtrees of all possible sizes. Bifurcation symmetry, being a particular aspect of structure, was found to be higher in the smaller than in the larger subtrees. This confirms a more delivering type of function for the small subtrees, as expected from intuitive arguments. Conversely, lower symmetry in larger subtrees relates to their conveying type of function. Moreover, different shapes of the tissue to be perfused lead to different symmetry properties of optimized tree models.