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A computerized method for measuring relative coronary arterial stenosis by cinevideodensitometric analysis of 35 mm coronary arteriograms was developed and validated. Video images of projected coronary arteriographic frames were digitized into a 512 X 512 matrix (256 gray levels) by computer analysis that compared integrated contrast density measured over stenotic and normal arterial segments after background subtraction. Pixel density was 70 to 80 pixels/mm2 actual area. In phantom studies performed on plexiglass cylinders, cinevideodensitometric measurements correlated linearly with concentration of contrast medium (r = .99), with cross-sectional areas (r = .99) of contrast-filled cylinders 1 to 4 mm in diameter over a wide range of contrast concentrations (25% to 100%), and with relative stenosis of eccentric lesions in the cylinders (r = .99, SEE = 3.9%). In postmortem studies of patients who died after undergoing coronary arteriography, videodensitometric measurements of relative stenosis correlated highly (r = .97, SEE = 7.0%) with percentage stenosis based on actual area measurements obtained histologically with computer-assisted microscopic planimetry. Cinevideodensitometric analysis of coronary arteriograms was reproducible (r = .92, SEE = 7.7%), and interobserver variability was low (r = .99, SEE = 4.3%). In addition, videodensitometry provided comparable values for eccentric coronary lesions filmed in right anterior oblique and left anterior oblique projections (r = .99, SEE = 1.9%). Cinevideodensitometric analysis is an accurate, rapid method for quantifying the relative stenosis of eccentric coronary lesions without manual tracing of arterial borders.

Quantification of relative coronary arterial stenosis by cinevideodensitometric analysis of coronary arteriograms.