Edge detection for coronary angiograms: error correction and impact of derivatives

The quantification of stenosed coronary arteries is influenced by several disturbances at image generation and by the contour detection itself. These factors are described, quantified, and, if possible, corrected to achieve an improved accuracy in measuring vessel diameters. The X-ray device causes a geometric distortion (pincushion effect). It is directed both radially and irregularly. Several correction methods have been applied to X-ray phantoms in order to increase the accuracy of measurement. The phantom study serves as a validation of the coronary analysis system and its correction methods. The accuracy of measurement was increased using image zoom and the correction of image distortion and pointspreading. With the help of the applied corrections the relative error in the range of small vessels was reduced from 77.2% down to 3.2%