Gradient vector analysis for quantification of type I collagen structure.

<p>Given a segmented image and voronoi construction we can quantify type I collagen alignment with respect to either the graph edge or node. Two cells, A, B are depicted in 3D space. The coordinates of these cells are given as , . The cell-graph edge was therefore represented as the vector . The red line gives the boundaries of the edge-based Voronoi diagram. For each pixel in this compartment the gradient vector that measures the direction of the maximum intensity change is calculated and the angle between the gradient vector and the cell-graph edge was calculated. Using the distribution of these angles, or the sum of all the gradient vectors we assessed direction and magnitude of collagen organization in 3D space.