In Vivo Flow Simulation at Coronary Bifurcation Reconstructed by Fusion of 3-Dimensional X-ray Angiography and Optical Coherence Tomography

High-quality reconstruction of coronary bifurcations is crucial in the evaluation of lesions, dedicated bifurcation stents, and stent techniques. Although 3-dimensional (3D) X-ray angiography restores natural bending of vascular structures, optical coherence tomography (OCT) provides an ultra–high resolution of the vessel wall morphology and stents at baseline and follow-up. We present a new method for 3D fusion of the 2 imaging modalities combined with flow simulation at the target bifurcation. A 63-year-old woman was admitted for percutaneous coronary intervention attributable to severe stenosis (Figure 1A) in the left anterior descending artery (LAD) at the bifurcation of the first diagonal branch (D1). The target bifurcation was reconstructed in 3D (Figure 1B) using a dedicated 3D QCA software package (QAngio XA 3D Research Edition 1.0, Medis Specials, Leiden, The Netherlands).1 Fusion of the 2 OCT pullbacks acquired in the LAD and in the D1 with the 3D QCA (Figure 1D and Video I in the online-only Data Supplement) was performed using QAngioOCT Advanced Edition (Medis Specials).2 The entire fusion procedure can be summarized in a few major steps as follows: (1) isocenter offset in the angiographic acquisition was corrected; (2) lumen edges at the bifurcation were automatically detected in the 2 angiographic projections; (3) automated reconstruction and modeling techniques were performed, resulting in a 3D lumen surface and a so-called reference surface, ie, the normal lumen as if the disease was not present; (4) the spatial correspondence, including alignment and angulation, of the OCT images with respect to the 3D angiographic reconstruction was determined based on the common carina position and the segmented OCT contours; (5) the OCT pullbacks were transformed and fused with the 3D angiographic reconstruction using …