Measuring pulmonary microvessel diameters using video image
analysis.
Hanger, Christopher C., Simon C. Hillier, Robert G. Presson, Jr, Robb
W. Glenny, and Wiltz W. Wagner, Jr.
Departments of Anesthesia, Physiology/Biophysics, and Pediatrics,
Indiana University School of Medicine, Indianapolis, Indiana 46202
and Department of Pulmonary and Critical Care Medicine, University of
Washington School of Medicine, Seattle, Washington 98195
APStracts 2:0139A, 1995.
To directly determine the pressure-diameter relationship of individual
pulmonary microvessels, it is necessary to measure the width of the
column of blood in the vessel because microvascular walls are
invisible when using intravital microscopy. To identify the margins
of the blood column accurately, we developed a method for computer
enhancement and measurement of vessel images. After recording
microvessels on videotape, consecutive frames from the videotape were
digitized by a computer. Pixels that changed from frame to frame
(moving erythrocytes) were turned white and unchanging pixels were
turned black. In this way an image of the red cell column with
distinct edges was produced. The width of this column was measured
using a heuristic technique involving interactions between the
computer and the user. The measurements were reproducible and
accurate. This technique has been used to measure microvascular
diameters over a range of well defined microvascular pressures and
construct precise pressure-diameter curves ().
Received 8 August 1994; accepted in final form 22 March 1995.
APS Manuscript Number A836-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 April 1995.