Optical Coherence Tomography for Patient-specific 3D Artery Reconstruction and Evaluation of Wall Shear Stress in a Left Circumflex Coronary Artery

Abstract

Image-based computational models for quantifying hemodynamic indices in stented coronary arteries often employ biplane angiography and intravascular ultrasound for 3D reconstruction. Recent advances in guidewire simulation algorithms and the rise of optical coherence tomography (OCT) suggest more precise coronary artery reconstruction may be possible. We developed a patientspecific method that combines the superior resolution of OCT with techniques for imaging wire pathway reconstruction adopted from graph theory. The wire pathway with minimum bending energy was determined by applying a shortest path algorithm to a graph representation of the artery based on prior studies indicating a wire adopts the straightest configuration within a tortuous vessel. Segments from OCT images are then registered orthogonal to the wire pathway using rotational orientation consistent with geometry delineated by computed tomography (CT). To demonstrate applicability, OCT segments within the stented region were combined with proximal and distal CT segments and imported into computational fluid dynamics software to quantify indices of wall shear stress (WSS). The method was applied to imaging data of a left circumflex artery with thrombus acquired immediately post-stenting and after a 6-month follow-up period. Areas of stent-induced low WSS returned to physiological levels at follow-up, but correlated with measurable neointimal thickness in OCT images. Neointimal thickness was negligible in areas of elevated WSS due to thrombus. This novel methodology capable of reconstructing a stented coronary artery may ultimately enhance our knowledge of deleterious hemodynamic indices induced by stenting after further investigation in a larger patient population.

Sequential Structural and Fluid Dynamics Analysis of Balloon-Expandable Coronary Stents: A Multivariable Statistical Analysis

“…Though limiting, this approach is not uncommon in the literature and many recent numerical studies have investigated stainless steel coronary stent designs. 14,19,20,25,[28][29][30][31]43,57,58,[64][65][66]69,70,73,80,89,91,92 Furthermore, one of the primary aims of this study was to assess the predictive nature of the numerical approach. This required that the relative performance of at least two of the investigated stents had been evaluated in large-scale clinical trials.…”

“…Following coronary stent deployment, sites of aggressive neointimal hyperplasia also correspond to sites subjected to non-physiological flow conditions, and this has been attributed to increased endothelial dysfunction and permeability. 6,17,18,20,21,52,71,79,88 The hemodynamic impact of the investigated stents was evaluated in terms of the relative residence time distribution predicted upon the lumen surface during the third cardiac cycle. The RRT accounts for temporal variations in both the magnitude and the orientation of the instantaneous wall shear stress vector and is calculated as follows:…”

“…6,17,18,20,21,52,71,79,88 In light of these observations, a significant body of research has been carried out in this area. Due to the difficulty involved in the evaluation of these phenomena in an in vivo setting however, a large portion of this research has been carried out using computational methods of analysis.…”

Computational replication of the patient-specific stenting procedure for coronary artery bifurcations: From OCT and CT imaging to structural and hemodynamics analyses

“…This study used a hybrid approach of CT angiography and OCT to reconstruct artery geometry within the stented region by mathematically determining the location of the OCT imaging wire during image acquisition (Ellwein et al, 2011). These method combines conventional and invasive high-resolution imaging modalities (Fig.…”

“…In several previous studies , Ellwein et al, 2011, Gundert et al, 2011and Mortier et al, 2015 patient-specific structural and fluid dynamic simulations were conducted. However, the post-operative geometry obtained after virtual stent deployment was rarely compared with the in vivo post-operative images .…”