Variability of quantitative digital subtraction coronary angiography before and after percutaneous transluminal coronary angioplasty

Abstract

Quantitative coronary angiography has been proposed as a means of reducing observer variability in the interpretation of coronary angiograms, especially before and after percutaneous transluminal coronary angioplasty (PTCA). Analysis of 13 consecutively acquired biplane digital subtraction angiograms before and after PTCA was undertaken to determine intra- and interobserver variability of absolute lesion diameter, relative videodensitometric cross-sectional area, automated percent diameter stenosis and visual percent diameter stenosis using a new fully automated quantitative computer program. The reliability of single-view measurements was also assessed. Both before and after PTCA, measures of absolute diameter showed less interobserver variability than densitometry, percent automated diameter stenosis and percent visual diameter stenosis measurements (before, r = 0.95, 0.83, 0.86, 0.70; after, 0.95, 0.88, 0.81, 0.62, respectively). Relative videodensitometric cross-sectional area correlated poorly with images from the orthogonal view (r = 0.46). These data suggest that quantitative angiography reduces variability from visual estimates; of all quantitative angiographic measurements, the highest interobserver reproducibility is achieved using absolute lesion diameter both before and after PTCA, probably because no operator interaction is needed to identify a "normal" segment. Unselected, single-view quantitative arteriography is poorly reproducible using videodensitometry. Therefore, automated determination of absolute lesion diameter in at least 2 projections provides the most reproducible evaluation of coronary lesions both before and after PTCA.

Evidence of endothelial dysfunction in angiographically normal coronary arteries of patients with coronary artery disease.

“…16 Similarly, analysis of interobserver variability for stenosis diameter in the human coronary artery showed high reproducibility (r= 0.97, SEE = 0.19 mm). 17 Briefly, the end-diastolic frames of the cineangiograms were projected on a Vanguard viewer that is optically coupled to a video camera. The video signal was digitized onto an ADAC Laboratories (Milpitas, California) digital angiographic computer.…”

Precision and reproducibility of quantitative coronary angiography with applications to controlled clinical trials. A sampling study.

“…Periodic diameter variations due to arterial pressure pulsation, however, have received less attention. In most studies, a single end-diastolic frame is selected because vessel motion and time dependency of the arterial diameter is believed to be minimal during this phase of the cardiac cycle (3,(24)(25)(26)(27). However, contrast concentration can be reduced by increased blood flow during diastole and this can reduce the precision of lesion measurement (1 1).…”

Reproducibility of Measurements of Coronary Narrowings by Videodensitometry and by Digital Calipers

“…percent area stenosis, diameter of the normal and stenotic segments, and cross-sec tional area of the normal and stenotic seg ments. Other workers [24] have also shown excellent reproducibility for percent area ste nosis using videodensitometric methods. We were able to obtain similarly excellent intraand interobserver correlations for 34 lesions measured at varying time intervals by two dif ferent observers.…”

“…Theoretically, these precautions should not be necessary for videodensitomet ric studies, but we [11] and others [24] have shown that measurements of lesions in differ ent projections give widely different results.…”