2009

Quantifying Therapeutic and Diagnostic Efficacy in 2D Microvascular Images

VESGEN is a newly automated, userinteractive program that maps and quantifies the effects of vascular therapeutics and regulators on microvascular form and function. VESGEN analyzes two-dimensional, black and white vascular images by measuring important vessel morphology parameters. This software guides the user through each required step of the analysis process via a concise graphical user interface (GUI). There are control options ranging from “one-click” analysis given a primary output, to step-by-step control over each image and algorithm used in an analysis. An option is provided to select a vascular tissue type, which determines the general collections of algorithms, intermediate images, and output images and measurements that will be produced. The UI automatically restructures itself to provide customized user controls for studying the requested type of tissue.

Three major types of vascular tissues can be analyzed: branching trees, networks, and tree-network composites. Parameters measured include vessel diameter, length, branchpoints, density, and fractal dimension. For tree type vessels, those measurements, as well as the number and tortuosity of vessels, are reported as dependent functions of vessel branching generation. VESGEN uses the fundamental image-processing concepts of 8-neighbor pixel connectivity, skeleton and distance map to create typically 5 to 12 (or greater) generations of vascular branching from a single parent vessel. For network type vessels, measurements of avascular regions are also made. Measurements of tree-network composites combine aspects of tree and network analyses.

Primary applications of the VESGEN code are 2D vascular images acquired as clinical diagnostic images of the human retina and as experimental studies of the effects of vascular regulators and therapeutics on vessel remodeling. Appli cations of VESGEN will be extended to predictive modeling studies of the response of human normal and pathological microvasculature to vascular therapeutics and regulators and to 3D vascular trees that are characteristic of organs such as the lung and brain.

VESGEN is written in Java as a plug-in for ImageJ (a free, publicly available image-processing software from National Institutes for Health). The software can be further modified for specific applications, or as an ImageJ-independent, standalone code. The current VESGEN program is at approximately Technology Readiness Level (TRL) 4-6, requiring only user knowledge of image pre-processing to binarize the vessels. The sole user input requirement is a binary (black/white) digital image in which the vascular architecture (i.e. vascular morphology or pattern) appears in black. An optional, but very useful and desirable, user input requirement is the microscope calibration factor, so that the quantified results output can be specified in physical units such as microns in addition to pixels.

This work was done by Patricia Parsons-Wingerter, Mary B. Vickerman, and Patricia A. Keith of Glenn Research Center. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Bio-Medical category.

Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steve Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-18277-1.

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