Practical approaches to microvessel analysis: Hotspots, microvessel density, and vessel proximity

This chapter reviews the approaches that have evolved over the last several decades to make quantitative measurements related to vascularity and angiogenesis in histology tissue sections. The early work focused on hotspot analysis, measuring antibody stained vessels in areas of intense vasculature on a tissue section. With the advent of whole slide scanning, newer algorithms could perform whole tissue section analysis, and quantify vascularity across an entire tumor section or other larger region of a microscope slide. The newest technique, one employed by the authors, uses vessel proximity as an approach to quantitation, where the percentage of a given cell type is quantified based on the degree of access to the vascular network. An example error analysis evaluation is provided, to assist in estimating the degree of error for a given quantitation approach. Challenges related to false positive detection of positive stained non-endothelial cells are discussed, and a further algorithm example discussed to address this area.