Three-dimensional Reconstruction Of Coronary Arteries Research Articles

Computational fluid dynamics with application of different theoretical flow models for the evaluation of coronary artery stenosis on CT angiography: comparison with invasive fractional flow reserve

The purpose of this study is to use the coronary computed tomography angiography (CCTA) to simulate the coronary blood flow with different theoretical flow models by using not only the computation fluid dynamics (CFD) method, but also additional patient boundary conditions obtained with echocardiography, and evaluate the feasibility of simulated fractional flow reserve (FFRCTS), compared with the invasive CTA-based FFR. The laminar and three turbulence models (k-ε(k-epsilon), k-ω(k-omega), SST (Menter’s shear stress transport)) were implemented to predict coronary blood flow. The study investigates an ideal stenosis model and six patients, with invasive FFR measurements. Three-dimensional reconstructions of coronary arteries of six subjects were performed from CCTA images of 320-detector scanner. The measured velocity profile of the left ventricular outflow tract from the echocardiography was employed for the inlet velocity in simulation. The pressure waveform of the patient aortic blood flow was used as the pressure profile at the outlet. With simulations, we found that the maximum velocity in the stenotic coronary artery reached about 395 cm s−1, which was about 2.4 times faster than the inlet velocity of 165 cm s−1 for the patient with coronary stenosis diagnosed 50%–75% on CTA. The pressure drop across the stenosis was about 28 mmHg. Meanwhile, the value of FFRCTS using the laminar flow pattern was 0.788 closely to its invasive FFR of 0.79. In conclusion, this study demonstrated that the CFD method has moderate more blood flow information to assess the hemodynamic significance of the coronary blood flow and calculate the non-invasive FFRCTS values, which were very close to those measured with invasive FFR.

Three-dimensional reconstruction of coronary arteries and plaque morphology using CT angiography - comparison and registration using IVUS.

The aim of this study is to present a new method for three-dimensional (3D) reconstruction of coronary arteries and plaque morphology using Computed Tomography (CT) Angiography. The method is summarized in three steps. In the first step, image filters are applied to CT images and an initial estimation of the vessel borders is extracted. In the second step, the 3D centerline is extracted using the center of gravity of each rough artery border. Finally in the third step, the borders and the plaque are detected and placed onto the 3D centerline constructing a 3D surface. By using as gold standard the results of a recently presented Intravascular Ultrasound (IVUS) plaque characterization method, high correlation is observed for calcium objects detected by CT and IVUS. The correlation coefficients for objects' volume, surface area, length and angle are r=0.51, r=0.89, r=0.96 and r=0.93, respectively.

Three-dimensional reconstruction of coronary arteries based on the integration of intravascular ultrasound and conventional angiography

BackgroundCoronary three-dimensional reconstruction with the combination of intravascular ultrasound and angiography offers advantages over computed tomography angiography of coronary arteries. The authors aimed to present the pilot phase of the validation of a new model of three-dimensional reconstruction of coronary arteries. MethodsThis study used angiography and intravascular ultrasound examinations already performed by clinical indication in individuals with known or suspected stable coronary artery disease. Image processing, segmentation, and three-dimensional reconstruction were conducted following specific methodology. For geometrical characterization purposes, tridimensional center lines were obtained. ResultsThree vessels were reconstructed: two left anterior descending arteries and one left circumflex artery. The vessel lumen volume and the overall plaque burden could be easily viewed with three-dimensional reconstruction. The geometric characterization revealed increased absolute values of length, tortuosity, curvature, and torsion, featuring a greater complexity of the center line of the diseased lumen relative to the center line of the external elastic membrane. ConclusionsThis new methodology, which integrates conventional angiography and intravascular ultrasound, has increased the practicality of the reconstructions, with a gain in volumetric accuracy of the vessel and overall visualization of key aspects of atherosclerotic disease, such as plaque remodeling and distribution.

Endothelial shear stress and coronary plaque characteristics in humans: combined frequency-domain optical coherence tomography and computational fluid dynamics study.

Despite the exposure of the entire vasculature to the atherogenic effects of systemic risk factors, atherosclerotic plaques preferentially develop at sites with disturbed flow. This study aimed at exploring in vivo the relationship between local endothelial shear stress (ESS) and coronary plaque characteristics in humans using computational fluid dynamics and frequency-domain optical coherence tomography. Three-dimensional coronary artery reconstruction was performed in 21 patients (24 arteries) presenting with acute coronary syndrome using frequency-domain optical coherence tomography and coronary angiography. Each coronary artery was divided into sequential 3-mm segments and analyzed for the assessment of local ESS and plaque characteristics. A total of 146 nonculprit segments were evaluated. Compared with segments with higher ESS [≥1 Pascal (Pa)], those with low ESS (<1 Pa) showed higher prevalence of lipid-rich plaques (37.5% versus 20.0%; P=0.019) and thin-cap fibroatheroma (12.5% versus 2.0%; P=0.037). Overall, lipid plaques in segments with low ESS had thinner fibrous cap (115 μm [63-166] versus 170 μm [107-219]; P=0.004) and higher macrophage density (normalized standard deviation: 8.4% [4.8-12.6] versus 6.2% [4.2-8.8]; P=0.017). Segments with low ESS showed more superficial calcifications (minimum calcification depth: 93 μm [50-140] versus 152 μm [105-258]; P=0.049) and tended to have higher prevalence of spotty calcifications (26.0% versus 12.0%; P=0.076). Coronary regions exposed to low ESS are associated with larger lipid burden, thinner fibrous cap, and higher prevalence of thin-cap fibroatheroma in humans. Frequency-domain optical coherence tomography-based assessment of ESS and wall characteristics may be useful in identifying vulnerable coronary regions. http://www.clinicaltrials.gov. Unique identifier: NCT01110538.

Abstract 18072: Low Endothelial Shear Stress is Associated With High-Risk Coronary Plaque Characteristics in Humans: A Three-Dimensional Frequency-Domain Optical Coherence Tomography Study

Introduction: Large lipid pool and thin fibrous cap are characteristics of plaques at high-risk for rupture resulting in adverse cardiac events. However, the local factors associated with the development of a rupture-prone plaque phenotype are not well known in humans. Endothelial shear stress (ESS) plays a major role in the development and progression of atherosclerotic plaques. We sought to investigate in vivo the relationship between computed ESS and plaque characteristics assessed by frequency-domain optical coherence tomography (FD-OCT). Methods: Three-dimensional coronary artery reconstruction was performed in 9 patients (4 left anterior descending, 2 left circumflex and 3 right coronary arteries) presenting with acute coronary syndrome using FD-OCT and coronary angiography. Each coronary artery was divided into sequential 3-mm segments, and each segment was analyzed for the assessment of predominant local ESS value by computational fluid dynamics and morphologic characteristics by FD-OCT. A total of 58 non-culprit segments without significant stenosis were evaluated. Results: Segments with low ESS (&lt;1 Pascal [Pa]) had significantly larger lipid arc (120.9° ± 36.2° vs. 82.5° ± 22.0°, p = 0.015) and thinner fibrous cap (172.7 ± 69.4 μm vs. 264.5 ± 110.5 μm, p = 0.008) compared to segments with higher ESS (≥1 Pa) (Figure). Segments with macrophage accumulation tended to have lower local ESS values (0.98 ± 0.42 Pa vs. 1.62 ± 1.50 Pa, p = 0.170) compared to those without macrophage accumulation. Similarly, segments with lipid-rich plaque (lipid arc &gt;90°) showed lower ESS values compared to those without lipid-rich plaque (1.06 ± 1.02 Pa vs. 1.78 ± 1.54 Pa, p = 0.177). Conclusions: The present study shows that coronary regions exposed to low ESS are characterized by larger lipid burden and thinner fibrous cap, suggesting that low ESS has a critical role in the development of vulnerable plaques.

CRT-107 Geometrically Accurate Three-Dimensional Coronary Artery Reconstruction Using Frequency-Domain Optical Coherence Tomography and Angiographic Data: New Opportunities for In Vivo Endothelial Shear Stress Assessment

Three-dimensional (3D) coronary artery reconstruction using intravascular ultrasound (IVUS) and angiographic data has been used in studies highlighting the critical role of endothelial shear stress (ESS) in coronary atherosclerosis. Frequency Domain Optical Coherence Tomography (FD-OCT) was recently

Three-Dimensional Reconstruction of Coronary Arteries and Its Application in Localization of Coronary Artery Segments Corresponding to Myocardial Segments Identified by Transthoracic Echocardiography

Objectives. To establish 3D models of coronary arteries (CA) and study their application in localization of CA segments identified by Transthoracic Echocardiography (TTE). Methods. Sectional images of the heart collected from the first CVH dataset and contrast CT data were used to establish 3D models of the CA. Virtual dissection was performed on the 3D models to simulate the conventional sections of TTE. Then, we used 2D ultrasound, speckle tracking imaging (STI), and 2D ultrasound plus 3D CA models to diagnose 170 patients and compare the results to coronary angiography (CAG). Results. 3D models of CA distinctly displayed both 3D structure and 2D sections of CA. This simulated TTE imaging in any plane and showed the CA segments that corresponded to 17 myocardial segments identified by TTE. The localization accuracy showed a significant difference between 2D ultrasound and 2D ultrasound plus 3D CA model in the severe stenosis group (P < 0.05) and in the mild-to-moderate stenosis group (P < 0.05). Conclusions. These innovative modeling techniques help clinicians identify the CA segments that correspond to myocardial segments typically shown in TTE sectional images, thereby increasing the accuracy of the TTE-based diagnosis of CHD.

Projection-based motion compensation for gated coronary artery reconstruction from rotational x-ray angiograms

Three-dimensional reconstruction of coronary arteries can be performed during x-ray-guided interventions by gated reconstruction from a rotational coronary angiography sequence. Due to imperfect gating and cardiac or breathing motion, the heart's motion state might not be the same in all projections used for the reconstruction of one cardiac phase. The motion state inconsistency causes motion artefacts and degrades the reconstruction quality. These effects can be reduced by a projection-based 2D motion compensation method. Using maximum-intensity forward projections of an initial uncompensated reconstruction as reference, the projection data are transformed elastically to improve the consistency with respect to the heart's motion state. A fast iterative closest-point algorithm working on vessel centrelines is employed for estimating the optimum transformation. Motion compensation is carried out prior to and independently from a final reconstruction. The motion compensation improves the accuracy of reconstructed vessel radii and the image contrast in a software phantom study. Reconstructions of human clinical cases are presented, in which the motion compensation substantially reduces motion blur and improves contrast and visibility of the coronary arteries.

In Vivo Comparative Study of Linear Versus Geometrically Correct Three-Dimensional Reconstruction of Coronary Arteries

Although conventional linear 3-dimensional (3D) reconstruction of coronary arteries by intravascular ultrasound has been widely used for the assessment of plaque volume and progression; the volumetric error (VE) that is produced has not been adequately studied. Linear and geometrically correct 3D reconstruction was applied in 16 coronary arterial segments from 9 patients. Using geometrically correct reconstruction as reference, VE was assessed in 1-mm-long arterial slices. Although for the entire length of the coronary arteries VEs for lumen, external elastic membrane (EEM), and intima-media volumes were minimal (lumen VE 0.4%, -0.8 to 1.8; EEM VE 0.3%, -0.9 to 1.9; intima-media VE 0.4%, -1.4 to 2.2), the VE in each arterial slice exhibited a large variation from -15.6% to 36.2% for lumen volume, from -12.9% to 33.1% for EEM volume, and from -17.2% to 46.7% for intima-media volume, suggesting that linear reconstruction over- or underestimates the true arterial volumes. Lumen VE, EEM VE, and intima-media VE were also significantly higher in curved arterial subsegments than in relatively straight arterial subsegments (p <0.05). In conclusion, in highly curved arterial subsegments, the VE that is produced by linearly stacking the intravascular ultrasound images may be not negligible. Geometrically correct reconstruction of coronary arteries provides more reliable arterial reconstructions and plaque volume measurements. It is anticipated that clinical application of this technique will contribute to more accurate follow-up of the progression of atherosclerosis and assessment of arterial remodeling.

A new method of three‐dimensional coronary artery reconstruction from X‐ray angiography: Validation against a virtual phantom and multislice computed tomography

To develop and implement a method for three-dimensional (3D) reconstruction of coronary arteries from conventional monoplane angiograms. 3D reconstruction of conventional coronary angiograms is a promising imaging modality for both diagnostic and interventional purposes. Our method combines image enhancement, automatic edge detection, an iterative method to reconstruct the centerline of the artery and reconstruction of the diameter of the vessel by taking into consideration foreshortening effects. The X-Ray-based 3D coronary trees were compared against phantom data from a virtual arterial tree projected into two planes as well as computed tomography (CT)-based coronary artery reconstructions in patients subjected to coronary angiography. Comparison against the phantom arterial tree demonstrated perfect agreement with the developed algorithm. Visual comparison against the CT-based reconstruction was performed in the 3D space, in terms of the direction angle along the centerline length of the left anterior descending and circumflex arteries relative to the main stem, and location and take-off angle of sample bifurcation branches from the main coronary arteries. Only minimal differences were detected between the two methods. Inter- and intraobserver variability of our method was low (intra-class correlation coefficients > 0.8). The developed method for coronary artery reconstruction from conventional angiography images provides the geometry of coronary arteries in the 3D space.

A method for 3D reconstruction of coronary arteries using biplane angiography and intravascular ultrasound images

The aim of this study is to describe a new method for the three-dimensional reconstruction of coronary arteries and its quantitative validation. Our approach is based on the fusion of the data provided by intravascular ultrasound images (IVUS) and biplane angiographies. A specific segmentation algorithm is used for the detection of the regions of interest in intravascular ultrasound images. A new methodology is also introduced for the accurate extraction of the catheter path. In detail, a cubic B-spline is used for approximating the catheter path in each biplane projection. Each B-spline curve is swept along the normal direction of its X-ray angiographic plane forming a surface. The intersection of the two surfaces is a 3D curve, which represents the reconstructed path. The detected regions of interest in the IVUS images are placed perpendicularly onto the path and their relative axial twist is computed using the sequential triangulation algorithm. Then, an efficient algorithm is applied to estimate the absolute orientation of the first IVUS frame. In order to obtain 3D visualization the commercial package Geomagic Studio 4.0 is used. The performance of the proposed method is assessed using a validation methodology which addresses the separate validation of each step followed for obtaining the coronary reconstruction. The performance of the segmentation algorithm was examined in 80 IVUS images. The reliability of the path extraction method was studied in vitro using a metal wire model and in vivo in a dataset of 11 patients. The performance of the sequential triangulation algorithm was tested in two gutter models and in the coronary arteries (marked with metal clips) of six cadaveric sheep hearts. Finally, the accuracy in the estimation of the first IVUS frame absolute orientation was examined in the same set of cadaveric sheep hearts. The obtained results demonstrate that the proposed reconstruction method is reliable and capable of depicting the morphology of coronary arteries.

Three-dimensional coronary artery reconstruction using fusion of intravascular ultrasound and biplane angiography

We have developed an efficient method for 3D reconstruction of coronary arteries. Our approach is based on the fusion of intravascular ultrasound (IVUS) and biplane angiography. The method includes an efficient algorithm for the automatic identification of the regions of interest in IVUS images and a novel methodology for the extraction of the catheter path from biplane angiographies. The estimation of IVUS frames relative twist and the computation of first IVUS frame absolute orientation is also investigated. To assess the performance of the method, a validation procedure is introduced. Several metrics are obtained to verify the reliability of our method in the description of coronary artery morphology.

Assessment of coronary compensatory enlargement by three-dimensional intravascular ultrasound.

Several techniques have been used to demonstrate that human arteries respond to atherosclerosis by increasing their total arterial area to prevent a decrease in blood flow. Three-dimensional reconstructions of coronary arteries can document this compensatory response accurately and specifically. Seven human coronary arteries were reconstructed using intravascular ultrasound and biplane angiography, and vessel geometries were quantified. In all seven vessels, as plaque area increased, overall vessel area increased (R = 0.986, 0.933, 0.984, 0.678, 0.763, 0.963, and 0.830), but luminal cross-sectional area did not significantly decrease. Focal compensatory enlargement was identified in each vessel, and in some cases this response appeared to occur until the vessel was 65% occluded. Luminal enlargement near the proximal ends was attributed to the natural taper of the vessel. The semi-automated, three-dimensional segmentation technique used in this study allows reproducible quantification, as there is no subjective manual tracing involved. Following the intravascular ultrasound transducer in time and space with biplane angiography allows for accurate reconstruction with or without automated pullback devices. Information on the rate of change of vessel measurements is also presented, which, when combined with visualization of accurate 3D geometry, provides a unique assessment of coronary compensatory enlargement. This reconstruction technique can be applied in a clinical environment with no major modification.

A knowledge-based approach for 3-D reconstruction and labeling of vascular networks from biplane angiographic projections

An approach to the three-dimensional reconstruction of coronary arteries is presented. The principal objective is to show how modeling of a vascular network, together with algorithmic procedures, can lead to accurate 3-D structure and feature labeling. The labeling problem is stated directly within the 3-D reconstruction framework. The reconstruction ambiguities inherent to biplane techniques are solved by means of a knowledge base, modeling of the object, and heuristic rules. Feasibility in near-real situations has been demonstrated. The critical importance of the object 3-D reference to achieving the data and modeling matching is emphasized, and a way to deal with it is pointed out. The overall system implies an incremental development in methodologies and experiments. All of them have been elaborated and tested independently, and the most appropriate ones have been selected for integration into a modular system. All the stages of the process (calibration, segmentation, reconstruction, and display) are discussed, with the main focus on modeling. Examples of automatic reconstruction from a phantom are provided.