Abstract:

Objective To evaluate the accuracy of coronary computed tomography angiography (CTA) on the imaging of near-critical stenosis using a pulsatile phantom of coronary arteries. Methods A pulsating cardiac phantom with acrylic tubes provided by GE CT lab was used to simulate beating heart and coronary arteries of two diameters (4 and 3 mm) and four stenosis degrees (40%, 45%, 55% and 60%) with plaques of two densities (800 Hu and 20 Hu simulating calcified plaque and soft plaque) at heart rate of 55 bpm. The contrast density was prepared to be 350 Hu inside the simulated vessels. The scans were performed with clinically typical parameters: 120 kV, 550 mA, 0.35 s/rotation, pitch 0.2. Based on the longitudinal images of the simulated coronary arteries, the stenosis rates were measured and compared with the actual values. In addition, the measured stenosis rates of different vessel sizes and plaque densities were compared.Results In the 4 mm vessels, all the stenosis parts were overestimated despite of density and stenosis degree. Even 40% stenosis could be overestimated as more than 50%. Measured stenosis rates with calcified plaques were higher than those with soft plaques (P<0.05). In the 3 mm vessels, only stenosis rate of 40% could be measured with calcified plaques, which was significantly overestimated. Stenosis caused by soft plaques were slightly overestimated in 3 mm vessels.Conclusion CTA tends to overestimate stenosis despite the composition of plaque, which may cause over-diagnose of coronary heart disease. Calcification can exaggerate the overestimation and cause trouble in stenosis determination.

Key words: X-ray computed tomography, coronary artery, phantom