Abstract 1906: Accuracy Of Stenosis Quantification By 64 Slice Computed Tomography And Quantitative Angiography Compared To Known Dimensions - A Phantom Study Using A Novel Coronary Model With Simulated Cardiac Motion
Background: Invasive coronary angiography has inherent limitations for displaying complex vascular anatomy to its two dimensional projection nature. Despite these limitations, it remains the gold standard for comparisons with new coronary imaging modalities, such as computed tomography (CT). The purpose of this study was to evaluate the accuracy of stenosis assessment by CT and quantitative coronary angiography (QCA) compared to known dimensions of a custom-designed coronary phantom with cardiac motion simulation.
Methods: Nineteen coronary vessel phantoms were used consisting of acrylic tubes with precisely drilled and measured dimensions. Each phantom had three stenoses of mild (25%), moderate (50%), and severe (75%) grade and of 4 different shapes: circular concentric, circular eccentric, non-circular regular, non-circular irregular, totaling 57 stenoses. The reference sites varied between 1.5 and 4 mm. Phantom imaging was performed at rest and with simulated cardiac motion at a heart rate of 60 bpm using a previously described cardiac motion pattern. Image acquisition was optimized for both imaging modalities and stenoses were quantified by blinded expert readers using contour detection software.
Results: Average % error (±SD) from the true diameter stenosis was overall similar for QCA (23.6±22.8) and for CT (20.3±19.2, n>0.05). However, QCA performed substantially worse with non-circular narrowings (36.6±24.4) compared to CT (15.9±10.2, p<0.001) while QCA was more accurate in circular stenoses (11.4±12.2) vs. CT (24.2±24.2, p<0.05). QCA underestimated the true narrowing by more than 20% in 4 of 30 circular stenoses compared with 16 of 27 non-circular narrowings. CT tended to overestimate stenoses (>20% in 14/57) rather than underestimate narrowings (9/57). There was no difference of accuracy in small vs. larger reference diameters or with or without simulated cardiac motion with either imaging modality.
Conclusions: QCA is inferior to CT in evaluating non-circular lumen stenoses, while it performed better than CT in circular narrowings. These results may have important implications for using QCA as gold standard for evaluating the accuracy of stenosis quantification by computed tomography.