3D In Vivo IVUS-Based Anisotropic FSI Models With Cyclic Bending for Human Coronary Atherosclerotic Plaque Mechanical Analysis

2009 ◽  
Author(s):  
Dalin Tang ◽  
Chun Yang ◽  
Jie Zheng ◽  
Pamela K. Woodard ◽  
Kristen Billiar ◽  
...  
Keyword(s):  
Atherosclerotic Plaque ◽  
Computational Models ◽  
Material Model ◽  
3D Models ◽  
Mechanical Analysis ◽  
Intraplaque Hemorrhage ◽  
Plaque Vulnerability ◽  
Cardiovascular Research ◽  
Cyclic Bending

Assessing atherosclerotic plaque vulnerability based on limited in vivo patient data has been a major challenge in cardiovascular research and clinical practice. Considerable advances in medical imaging technology have been made in recent years to identify vulnerable atherosclerotic carotid plaques in vivo with information about plaque components including lipid-rich necrotic pools, calcification, intraplaque hemorrhage, loose matrix, thrombosis, and ulcers, subject to resolution limitations of current technology [1]. Image-based computational models have also been developed which combine mechanical analysis with image technology aiming for more accurate assessment of plaque vulnerability and better diagnostic and treatment decisions [2]. However, 3D models with fluid-structure interactions (FSI), cyclic bending and anisotropic properties based on in vivo IVUS images for human coronary atherosclerotic plaques are lacking in the current literature. In this paper, we introduce 3D FSI models based on in vivo IVUS images to perform mechanical analysis for human coronary plaques. Cyclic bending is included to represent deformation caused by cardiac motion. An anisotropic material model was used for the vessel so that the models would be more realistic for more accurate computational flow and stress/strain predictions.

A Predictive Method for Human Carotid Plaque Rupture Using In Vivo Serial MRI With Follow-Up Scan Showing Actual Rupture and MRI-Based 3D Models With Fluid-Structure Interactions

2011 ◽  
Author(s):  
Zheyang Wu ◽  
Chun Yang ◽  
Dalin Tang
Keyword(s):  
Atherosclerotic Plaque ◽  
Carotid Plaque ◽  
Plaque Rupture ◽  
3D Models ◽  
Mechanical Analysis ◽  
Predictive Method ◽  
Magnetic Resonance Imaging Mri ◽  
Serial Mri

It has been hypothesized that mechanical risk factors may be used to predict future atherosclerotic plaque rupture. Much progress has been made in computational modeling, medical imaging, and mechanical analysis for atherosclerotic plaque vulnerability assessment in recent years [1–2]. However, truly predictive methods to predict plaque rupture are currently lacking in the literature and practice. In this paper, we introduce a procedure using computational and statistical models based on serial magnetic resonance imaging (MRI) to quantify sensitivity and specificity of mechanical predictors and their combinations to identify the best candidate for rupture prediction. Serial MRI of carotid plaque from a patient with follow-up scan showing ulceration (rupture) was acquired and the actual appearance of ulceration was used as “gold standard” and validation for the predictive method.

scholarly journals Multi-patient study for coronary vulnerable plaque model comparisons: 2D/3D and fluid–structure interaction simulations

2021 ◽  
Author(s):  
Qingyu Wang ◽  
Dalin Tang ◽  
Liang Wang ◽  
Akiko Meahara ◽  
David Molony ◽  
...  
Keyword(s):  
Computational Models ◽  
Wall Stress ◽  
3D Models ◽  
Coronary Plaque ◽  
Maximum Pressure ◽  
Plaque Progression ◽  
Fluid Structure ◽  
Cyclic Bending ◽  
Model Comparisons

AbstractSeveral image-based computational models have been used to perform mechanical analysis for atherosclerotic plaque progression and vulnerability investigations. However, differences of computational predictions from those models have not been quantified at multi-patient level. In vivo intravascular ultrasound (IVUS) coronary plaque data were acquired from seven patients. Seven 2D/3D models with/without circumferential shrink, cyclic bending and fluid–structure interactions (FSI) were constructed for the seven patients to perform model comparisons and quantify impact of 2D simplification, circumferential shrink, FSI and cyclic bending plaque wall stress/strain (PWS/PWSn) and flow shear stress (FSS) calculations. PWS/PWSn and FSS averages from seven patients (388 slices for 2D and 3D thin-layer models) were used for comparison. Compared to 2D models with shrink process, 2D models without shrink process overestimated PWS by 17.26%. PWS change at location with greatest curvature change from 3D FSI models with/without cyclic bending varied from 15.07% to 49.52% for the seven patients (average = 30.13%). Mean Max-FSS, Min-FSS and Ave-FSS from the flow-only models under maximum pressure condition were 4.02%, 11.29% and 5.45% higher than those from full FSI models with cycle bending, respectively. Mean PWS and PWSn differences between FSI and structure-only models were only 4.38% and 1.78%. Model differences had noticeable patient variations. FSI and flow-only model differences were greater for minimum FSS predictions, notable since low FSS is known to be related to plaque progression. Structure-only models could provide PWS/PWSn calculations as good approximations to FSI models for simplicity and time savings in calculation.

scholarly journals 3D MRI-Based Anisotropic FSI Models With Cyclic Bending for Human Coronary Atherosclerotic Plaque Mechanical Analysis

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Dalin Tang ◽  
Chun Yang ◽  
Shunichi Kobayashi ◽  
Jie Zheng ◽  
Pamela K. Woodard ◽  
...  
Keyword(s):  
Atherosclerotic Plaque ◽  
Vulnerability Assessment ◽  
Computational Models ◽  
Plaque Rupture ◽  
Maximum Velocity ◽  
Coronary Plaque ◽  
Plaque Vulnerability ◽  
Stress Strain ◽  
Axial Stretch ◽  
Cyclic Bending

Heart attack and stroke are often caused by atherosclerotic plaque rupture, which happens without warning most of the time. Magnetic resonance imaging (MRI)-based atherosclerotic plaque models with fluid-structure interactions (FSIs) have been introduced to perform flow and stress/strain analysis and identify possible mechanical and morphological indices for accurate plaque vulnerability assessment. For coronary arteries, cyclic bending associated with heart motion and anisotropy of the vessel walls may have significant influence on flow and stress/strain distributions in the plaque. FSI models with cyclic bending and anisotropic vessel properties for coronary plaques are lacking in the current literature. In this paper, cyclic bending and anisotropic vessel properties were added to 3D FSI coronary plaque models so that the models would be more realistic for more accurate computational flow and stress/strain predictions. Six computational models using one ex vivo MRI human coronary plaque specimen data were constructed to assess the effects of cyclic bending, anisotropic vessel properties, pulsating pressure, plaque structure, and axial stretch on plaque stress/strain distributions. Our results indicate that cyclic bending and anisotropic properties may cause 50–800% increase in maximum principal stress (Stress-P1) values at selected locations. The stress increase varies with location and is higher when bending is coupled with axial stretch, nonsmooth plaque structure, and resonant pressure conditions (zero phase angle shift). Effects of cyclic bending on flow behaviors are more modest (9.8% decrease in maximum velocity, 2.5% decrease in flow rate, 15% increase in maximum flow shear stress). Inclusion of cyclic bending, anisotropic vessel material properties, accurate plaque structure, and axial stretch in computational FSI models should lead to a considerable improvement of accuracy of computational stress/strain predictions for coronary plaque vulnerability assessment. Further studies incorporating additional mechanical property data and in vivo MRI data are needed to obtain more complete and accurate knowledge about flow and stress/strain behaviors in coronary plaques and to identify critical indicators for better plaque assessment and possible rupture predictions.

scholarly journals Modelling approaches for evaluating multiscale tendon mechanics

2016 ◽  
Vol 6 (1) ◽  
pp. 20150044 ◽  
Author(s):  
Fei Fang ◽  
Spencer P. Lake
Keyword(s):  
Computational Models ◽  
Mechanical Response ◽  
Helical Structure ◽  
Mechanical Analysis ◽  
Hierarchical Organization ◽  
Organization Model ◽  
Tendon Mechanics ◽  
Modelling Approaches

Tendon exhibits anisotropic, inhomogeneous and viscoelastic mechanical properties that are determined by its complicated hierarchical structure and varying amounts/organization of different tissue constituents. Although extensive research has been conducted to use modelling approaches to interpret tendon structure–function relationships in combination with experimental data, many issues remain unclear (i.e. the role of minor components such as decorin, aggrecan and elastin), and the integration of mechanical analysis across different length scales has not been well applied to explore stress or strain transfer from macro- to microscale. This review outlines mathematical and computational models that have been used to understand tendon mechanics at different scales of the hierarchical organization. Model representations at the molecular, fibril and tissue levels are discussed, including formulations that follow phenomenological and microstructural approaches (which include evaluations of crimp, helical structure and the interaction between collagen fibrils and proteoglycans). Multiscale modelling approaches incorporating tendon features are suggested to be an advantageous methodology to understand further the physiological mechanical response of tendon and corresponding adaptation of properties owing to unique in vivo loading environments.

Computational Plaque Vulnerability Index for Atherosclerotic Carotid Plaque Assessment Based on In Vivo MR-Image

2008 ◽  
Author(s):  
Zhongzhao Teng ◽  
Xueying Huang ◽  
Chun Yuan ◽  
Gador Canton ◽  
Fei Liu ◽  
...  
Keyword(s):  
Atherosclerotic Plaque ◽  
Carotid Plaque ◽  
Vulnerability Index ◽  
Carotid Atherosclerotic Plaque ◽  
Plaque Vulnerability ◽  
Mr Image ◽  
Noninvasive Methods ◽  
Screening And Diagnosis

Carotid atherosclerotic plaque (CAP) may rupture without warning and cause acute cardiovascular syndromes such as stroke, which is the No.3 killer in USA and a leading cause of serious disabilities. Available screening and diagnosis techniques are insufficient to identify those victims before the event occurs. Noninvasive methods to identify new and emerging biomarkers to assess plaque vulnerability and predict possible rupture before the fatal event are urgently called for.

Abstract 1143: Imaging of Vasa Vasorum in Atherosclerotic Plaque with 99m Tc-labeled single chain-VEGF

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Satoru Ohshima ◽  
Shinichiro Fujimoto ◽  
Sotirios Tsimikas ◽  
Frank D Kolodgie ◽  
Renu Virmani ◽  
...  
Keyword(s):  
Atherosclerotic Plaque ◽  
Ex Vivo ◽  
Imaging Modality ◽  
Atherosclerotic Lesion ◽  
Vasa Vasorum ◽  
Intraplaque Hemorrhage ◽  
Control Group ◽  
High Cholesterol Diet ◽  
Single Chain

Introduction: Adventitial vasa vasorum proliferation and neointimal neovascularization are associated with intraplaque hemorrhage, expansion of necrotic core and hence plaque vulnerability. Increased expression of VEGF and its receptors accompany neoangiogenic process. We used 99m Tc -labeled single chain VEGF (TcV) for developing potentially noninvasive imaging modality in experimentally induced aortic atherosclerotic lesion. Methods : Noninva-sive radionuclide imaging was performed with TcV (6.85 ±0. 27 mCi) in 6 NZW rabbits receiving high cholesterol diet (0.2% cholesterol, 4% fat) for one year and compared with 3 control rabbits receiving normal rabbit chow. Four hours after intravenous administration of TcV, micro SPECT/microCT imaging was performed for in vivo localization of tracer activity. Aortas were then explanted, and gamma counted for determination of % injected dose per gram (%ID/g). The aortas were then submitted for histopathologic characterization. Results : The uptake in thoracic aorta was clearly visualized non-invasively by TcV in vivo imaging in 4 of 5 rabbits in hypercholesterolemic rabbits, but not in the control animals. The %ID/g of each parts of aorta in hypercholesterolemic rabbits (Arch : 0.036 ± 0.020 %, Thoracic : 0.026 ± 0.012 %, Abd : 0.019 ± 0.009 %) was about 2.5-fold higher than that in control group (Arch : 0.014 ± 0.004 %, Thoracic : 0.009 ± 0.003 %, Abd : 0.009 ± 0.003 %) (figure a ). Ex vivo images of each group are shown as figure b . Conclusions : This preliminary study suggests a potentially novel strategy for non-invasive imaging of neoangiogenesis in atherosclerotic plaque and may allow identification of unstable plaques.

Impact of Patient-Specific In Vivo Vessel Material Properties on Carotid Atherosclerotic Plaque Stress/Strain Calculations

2019 ◽  
Vol 16 (03) ◽  
pp. 1842002 ◽  
Author(s):  
Qingyu Wang ◽  
Dalin Tang ◽  
Gador Canton ◽  
Thomas S. Hatsukami ◽  
Kristen L. Billiar ◽  
...  
Keyword(s):  
Material Properties ◽  
Carotid Plaque ◽  
Computational Models ◽  
Patient Specific ◽  
Stress And Strain ◽  
Carotid Atherosclerotic Plaque ◽  
Plaque Vulnerability ◽  
Material Models ◽  
Vessel Material

Patient-specific vessel material properties are in general lacking in image-based computational models. Carotid plaque stress and strain conditions with in vivo material and old material models were investigated (8 patients, 16 plaques). Plaque models using patient-specific in vivo vessel material properties showed significant differences from models using old material properties from the literature on stress and strain calculations. These differences demonstrated that models using in vivo material properties could improve the accuracy of stress and strain calculations which could potentially lead to more accurate plaque vulnerability assessment.

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