The analysis of the vasculature of a tumour can be based on the some of the geometric parameters of the vessels, such as diameter of the vessels, number of branching points, length between branching points, or density of vessels in a given area. The following example illustrates how to perform the geometric analysis using MATLAB and some specifically designed funcions. The analysis is based on a technique called "Scale Space" which progressively blurs an image to observe its characteristics at different "scales": fine details will be observed at the first scales and then will be erased as the image is filtered, whilst larger characteristics will dominate the lower scales.
This work was was accepted for publication in Microvascular Research:
Online chromatic and scale-space microvessel-tracing analysis for transmitted light optical images CC Reyes-Aldasoro, MA Björndahl, S Akerman, J Ibrahim, MK Griffiths, GM Tozer, Microvascular research 84 (3), 330-339

For more detail on Scale-Space, the paper by Lindeberg explains the technique: (http://www.nada.kth.se/~tony/earlyvision.html)