ABSOLUTE CROSS-SECTIONAL AREA MEASUREMENTS IN QUANTITATIVE CORONARY ARTERIOGRAPHY BY DUAL-ENERGY DSA

Recent studies have emphasized the limitations of conventional coronary angiography. These limitations include the lack of correlation between the severity of coronary stenosis as estimated from coronary angiograms and the actual severity of stenotic lesions measured in postmortem hearts. As a result, attempts have been made to quantitate luminal dimension more precisely. The application of quantitative digital subtraction angiography (DSA) in the assessment of coronary artery lesion dimension has been limited by cardiac and respiratory motion artifacts. We have reported previously on a motion-immune dual-energy (DE) cardiac mode in which kVp and filtration are switched at 30 Hz. To assess the potential advantages of a videodensitometric technique for quantification of absolute vessel cross-sectional area (CSA), three different quantitative coronary arteriography (QCA) algorithms were compared. The three algorithms under comparison were a videodensitometric (V) algorithm, which does not require any geometric assumption for absolute vessel CSA measurement, and videodensitometric (VC) and edge detection (ED) algorithms, which do require the assumption of circular cross-section for CSA measurements. A cylindrical vessel phantom (0.5-4.75 mm in diameter) and a crescentic vessel phantom, producing 25% to 90% area stenosis, were imaged over the chest of a humanoid phantom. The low- and high-energy images were corrected for scatter and veiling glare before energy subtraction. For CSA measurements in crescentic vessel phantoms, the V algorithm produced significantly improved results (slope = 0.87, intercept = 0.51 mm2, r = .95) when compared to the VC (slope = 1.05, intercept = 4.19 mm2, r = .75) and the ED (slope = 1.57, intercept = 5.21 mm2, r = .60) algorithms.