Digital geometric measurements in comparison to cinefilm analysis of coronary artery dimensions

Six months follow‐up post‐PTCA angiograms from 31 patients were acquired digitally and on cinefilm and used for a comparison of geometric coronary measurements at the site of the previous dilatation. On 70 images of 34 coronary segments quantitative analysis was performed both on‐line, using the Automated Coronary Analysis package of the Philips Digital Cardiac Imaging System (DCI, pixel matrix 512 × 512) and off‐line, using the Cardiovascular Angiography Analysis System (CAAS). With the CAAS a cine‐video conversion is performed and a 6.9 × 6.9 mm region of interest from the 18 × 24 mm cineframe is digitized into a 512 × 512 pixel matrix. In both systems the vascular contours are assessed by means of operator‐independent edge detection algorithms. The angiographic catheter was used for calibration. Best agreement between DCI and CAAS was found for obstruction diameter and minimal luminal diameter, respectively (r = 0.82; y = 0.12 + 0.97x; SEE = 0.29). The reconstructed reference diameter related to a computed reference contour yields lower correlation (r = 0.76; y = 0.27 + 0.91x; SEE = 0.37). Worst results were obtained from the relative measure of percent diameter stenosis as well as from the derived parameter of plaque area. The on‐line digital approach of geometric coronary assessments provides good agreement with cinefilm analysis when direct measurements of coronary dimensions are applied. © 1993 Wiley‐Liss, Inc.