Three dimensional reconstruction of coronary artery stents from optical coherence tomography: experimental validation and clinical feasibility

Figure 1. Patient-specific silicone models. In each model from left to right: angiography, computer-aided design before stenting, OCT-reconstructed lumen after stenting, and stereoscopy images of the final stented models. In stereoscopy images, the arrows indicate the markers used as reference for the orientation of the 3D reconstructed lumen.

Figure 2. OCT stent segmentation and planar unrolling. (a) Segmented stent contour (white circle), and (b) segmented strut points (white boxes), and arrows indicate the markers used as reference for the orientation of the 3D reconstructed lumen, (c) Packaging of segmented stent contours and strut points in space, (d) Rotation and straightening of the packaged stent contours and strut points, (e, f) Planar unrolling (stent contours in red, stent strut points in green). The purple strut points were added to show the continuity of the stent structure. In (e, f), note the zone of missing strut points corresponding to the wire shadow. (a–e) Depict Onyx stent and (f) Synergy stent.

Figure 3. Planar stent wireframe reconstruction and rolling back to space. Planar computer-aided design of (a) Onyx stent and (d) Synergy stent with the boundaries delineated by red lines. Planar stent reconstruction (black lines) of (b) Onyx and (e) Synergy using the unrolled stent strut points and computer-aided stent designs as reference. The numbers and circles in (a, b, d, e) indicate the location of stent links. Note the extension of black lines beyond the stent boundaries to show the stent continuity for the next steps. Rolling back of 2D reconstructed (c) Onyx stent wireframe and (f) Synergy stent wireframe and volume creation: (c1, f1) 3D reconstructed lumen used as a backbone for the 3D stent reconstruction. The red points are segmented stent strut points, (c2, f2) 3D rolling-back of 2D reconstructed stent wireframe (blue) following the lumen shape, (c3, f3) Original strut points (red) overlapped on the rolled back stent wireframe, (c4, f4) Final stent volume generated from stent wireframe. A tube was added inside the stent wireframe for better visualization (c2, c3, f2, f3). Stent designs were provided by the stent manufacturers.

Figure 4. Qualitative experimental validation of stent reconstruction method against μCT and stereoscopic imaging. (a–d) Note the agreement in the link position (blue boxes in OCT-stent reconstructions and red boxes in μCT-stent reconstruction and stereoscopy). In OCT and μCT-based reconstructed models, a tube was inserted for better visualization, whereas in stereoscopy images, a small balloon was inflated in very low pressures for better visualization, (e) Malapposed struts in OCT-stent reconstruction (red stent) at the same location and magnitude compared to μCT-stent reconstruction (black stent).

Figure 5. Quantitative experimental validation of stent reconstruction method against μCT. (a) Stent size measured by mean stent diameter (MSD), and (b) Stent shape measured by ellipse ratio.

Figure 6. Inter-observer reproducibility of OCT-stent reconstructions. (a) Qualitative agreement by overlapping the two reconstructed stents. (b) Quantitative agreement for each model (MSD, mean stent diameter) and overall agreement using Bland–Altman analysis.

Figure 7. Clinical feasibility of the proposed 3D stent reconstruction method. (a) Invasive coronary angiography post stenting, (b) 3D lumen and stent reconstruction. Note the qualitative agreement to angiography, (c) meshing of a fluid domain in the stented lumen, (d) computational fluid dynamics (CFD) analysis depicting the time-averaged wall shear stress (TAWSS, Pa) along the stented bifurcations.

Figure 8. Representative examples of the calculated hemodynamic microenvironment (strut level) in patient-specific 3D reconstructed stented bifurcations. (a–c) The time-averaged wall shear stress (TAWSS, Pa) around stent struts. In (a) note the increased wall shear stress on the luminal surface of a well-apposed strut, and in (b–c) the wall shear stress distribution around malapposed struts denoted with white asterisks. In (d) longitudinal section showing the low velocity between the lumen and malapposed struts (white asterisks). (e–g) TAWSS distribution at the ostium of the side branch. Note the struts jailing the ostium of the side branch.