Experimental comparisons of optical coherence tomography-based versus angiography-based time-averaged wall shear stress estimations.

An approach to rapid simulation of time-averaged wall shear stress (TAWSS) on 3D geometries created from 3D Quantitative Coronary Angiography (3D-QCA) methodology has been developed, which enables rapid computational fluid dynamic (CFD) shear stress simulation. We compared TAWSS estimated from 3D-QCA-CFD with optical coherence tomography (OCT)-based CFD simulations in coronary arteries. 15 normal and 5 stenotic coronary arteries in instrumented minipigs were studied. 3D arterial geometries were reconstructed from 3D-QCA and OCT using common centrelines and matched axial positions. Identical boundary conditions were used for both methods through directly measured vessel-specific inlet blood velocities. TAWSS was calculated for axially matched segments (n = 80 for normal arteries; n = 160 for stenotic arteries) and in 3 mm/60° sectors. Mean TAWSS simulation times for 3D-QCA and OCT-based CFD were 17.8 min and ~ 1.5 h respectively. There were significant but numerically small differences in TAWSS for normal arteries (-0.21 ± 0.64 Pa [95%CI -1.04,1.46], p < 0.001), and no significant difference for stenotic arteries (-0.39 ± 3.04 Pa [95%CI -6.35, 5.56], p = 0.25). Axial TAWSS profiles along vessel lengths were similar between the two methods. There is a trend of underestimation by 3D-QCA at higher values of TAWSS compared with OCT, due to differences in geometry dimensions. Similar spatial distributions of TAWSS in both normal and stenotic arteries were observed from co-registered TAWSS maps. This study suggests that 3D-QCA-based TAWSS is feasible in both normal and stenotic arteries and that further clinical evaluation of rapid TAWSS from 3D-QCA is warranted, which may facilitate clinical adoption of TAWSS assessment.