Patient-Specific Modelling of Intracranial Aneurysm Evolution

2011 ◽  
Author(s):  
Paul N. Watton ◽  
Marc Homer ◽  
Justin Penrose ◽  
Harry Thompson ◽  
Haoyu Chen ◽  
...  
Keyword(s):  
Arterial Wall ◽  
Adult Population ◽  
Computational Simulation ◽  
Clinical Intervention ◽  
Patient Specific ◽  
Computational Framework ◽  
Important Concern ◽  
Risk Of Rupture ◽  
Appropriate Therapy ◽  
Insight Into

Intracranial aneurysms appear as sac-like outpouchings of the cerebral vasculature wall; inflated by the pressure of the blood that fills them. They are relatively common and affect up to 5% of the adult population. Fortunately, most remain asymptomatic. However, there is a small but inherent risk of rupture: 0.1% to 1% of detected aneurysms rupture every year. If rupture does occur there is a 30% to 50% chance of fatality. Consequently, if an aneurysm is detected, clinical intervention may be deemed appropriate. Therapy is currently aimed at pre-rupture detection and preventative treatment. However, interventional procedures are not without risk to the patient. The improvement and optimization of interventional techniques is an important concern for patient welfare and is necessary for rationalisation of healthcare priorities. Hence there is a need to develop methodologies to assist in identifying those ICAs most at risk of rupture. We focus on the mathematical modelling and computational simulation of ICA evolution. Models must take into consideration: (i) the biomechanics of the arterial wall; (ii) the biology of the arterial wall and (iii) the complex interplay between (i) and (ii), i.e. the mechanobiology of the arterial wall. The ultimate ambition of such models is to aid clinical diagnosis on a patient-specific basis. However, due to the significant biological complexity coupled with limited histological information such models are still in their relative infancy. Current research focuses on simulating the evolution of an ICA with an aim to yield insight into the growth and remodelling (G&R) processes that give rise to inception, enlargement, stabilisation and rupture. We present a novel Fluid-Structure-Growth computational framework for modelling aneurysm evolution.

Computational Fluid Dynamics and Solid Mechanics Analyses of a Patient-Specific AAA Pre- and Post-EVAR

2004 ◽  
Author(s):  
Christine M. Scotti ◽  
Ender A. Finol ◽  
Siddharth Viswanathan ◽  
Aleksandr Shkolnik ◽  
Elena S. DiMartino ◽  
...  
Keyword(s):  
Arterial Wall ◽  
Solid Mechanics ◽  
Morphological Changes ◽  
Thrombus Formation ◽  
Endovascular Aneurysm Repair ◽  
Aneurysm Rupture ◽  
Patient Specific ◽  
Minimally Invasive Surgical ◽  
Increased Risk ◽  
Risk Of Rupture

The establishment of a new pathway for blood flow immediately following endovascular aneurysm repair (EVAR) results in morphological changes and remodeling of the aneurismal sac. While EVAR is a minimally invasive surgical intervention, failure of the endovascular graft (EVG) may occur in which there is downstream migration and endoleak formation, creating a repressurization of the aneurismal sac and an increased risk of rupture. While the mechanism of aneurysm rupture and EVG failure is fundamental in nature, the factors that most significantly contribute to the end result are not yet fully understood. Mechanically, both are the consequence of an exerted force or disturbance exceeding the strength of a given material, whether it is the aneurismal arterial wall or the interaction that exists between the graft and wall. Embedded within this causal relationship are the contributions of arterial wall remodeling, intraluminal thrombus formation, and the dynamics that exists within the lumen. Several studies have been performed to examine these factors individually as they affect shear stress, the development of vortices, and the mechanical stress experienced along the arterial wall. However, a complete investigation is needed to study an anatomically realistic geometry operating under physiological conditions. The computational analyses conducted in this investigation address the confluence of these factors as they are modeled within an accurate patient-specific abdominal aortic aneurysm (AAA) reconstructed from CT scan data prior to and after EVAR. Our results verify the pressure-dominated characteristic of the flow and the negligible contribution of the dynamic and frictional force components; both are in good agreement with previously published results for analytical estimation of flow-induced forces in EVGs. [1]

scholarly journals An MRI-Based Patient-Specific Computational Framework for the Calculation of Range of Motion of Total Hip Replacements

2021 ◽  
Vol 11 (6) ◽  
pp. 2852
Author(s):  
Maeruan Kebbach ◽  
Christian Schulze ◽  
Christian Meyenburg ◽  
Daniel Kluess ◽  
Mevluet Sungu ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Internal Rotation ◽  
Computer Aided Design ◽  
External Rotation ◽  
Patient Specific ◽  
Computational Framework ◽  
Total Hip ◽  
Total Hip Replacements ◽  
Significant Difference ◽  
Hip Replacements

The calculation of range of motion (ROM) is a key factor during preoperative planning of total hip replacements (THR), to reduce the risk of impingement and dislocation of the artificial hip joint. To support the preoperative assessment of THR, a magnetic resonance imaging (MRI)-based computational framework was generated; this enabled the estimation of patient-specific ROM and type of impingement (bone-to-bone, implant-to-bone, and implant-to-implant) postoperatively, using a three-dimensional computer-aided design (CAD) to visualize typical clinical joint movements. Hence, patient-specific CAD models from 19 patients were generated from MRI scans and a conventional total hip system (Bicontact® hip stem and Plasmacup® SC acetabular cup with a ceramic-on-ceramic bearing) was implanted virtually. As a verification of the framework, the ROM was compared between preoperatively planned and the postoperatively reconstructed situations; this was derived based on postoperative radiographs (n = 6 patients) during different clinically relevant movements. The data analysis revealed there was no significant difference between preoperatively planned and postoperatively reconstructed ROM (∆ROM) of maximum flexion (∆ROM = 0°, p = 0.854) and internal rotation (∆ROM = 1.8°, p = 0.917). Contrarily, minor differences were observed for the ROM during maximum external rotation (∆ROM = 9°, p = 0.046). Impingement, of all three types, was in good agreement with the preoperatively planned and postoperatively reconstructed scenarios during all movements. The calculated ROM reached physiological levels during flexion and internal rotation movement; however, it exceeded physiological levels during external rotation. Patients, where implant-to-implant impingement was detected, reached higher ROMs than patients with bone-to-bone impingement. The proposed framework provides the capability to predict postoperative ROM of THRs.

scholarly journals Fluid–structure interactions (FSI) based study of low-density lipoproteins (LDL) uptake in the left coronary artery

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xueping Chen ◽  
Jian Zhuang ◽  
Huanlei Huang ◽  
Yueheng Wu
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Left Coronary Artery ◽  
Arterial Wall ◽  
Low Density Lipoproteins ◽  
Patient Specific ◽  
Low Density ◽  
Fluid Structure ◽  
Flowing Blood ◽  
Stress Dependent

AbstractThe purpose of this study is to compare the effect of the different physical factors on low-density lipoproteins (LDL) accumulation from flowing blood to the arterial wall of the left coronary arteries. The three-dimensional (3D) computational model of the left coronary arterial tree is reconstructed from a patient-specific computed tomography angiography (CTA) image. The endothelium of the coronary artery is represented by a shear stress dependent three-pore model. Fluid–structure interaction ($$FSI$$ FSI ) based numerical method is used to study the LDL transport from vascular lumen into the arterial wall. The results show that the high elastic property of the arterial wall decreases the complexity of the local flow field in the coronary bifurcation system. The places of high levels of LDL uptake coincide with the regions of low wall shear stress. In addition, hypertension promotes LDL uptake from flowing blood in the arterial wall, while the thickened arterial wall decreases this process. The present computer strategy combining the methods of coronary CTA image 3D reconstruction, $$FSI$$ FSI simulation, and three-pore modeling was illustrated to be effective on the simulation of the distribution and the uptake of LDL. This may have great potential for the early prediction of the local atherosclerosis lesion in the human left coronary artery.

scholarly journals A flexible framework for sequential estimation of model parameters in computational hemodynamics

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Christopher J. Arthurs ◽  
Nan Xiao ◽  
Philippe Moireau ◽  
Tobias Schaeffter ◽  
C. Alberto Figueroa
Keyword(s):  
Unscented Kalman Filter ◽  
Three Dimensional ◽  
Synthetic Data ◽  
Sequential Estimation ◽  
Wall Material ◽  
Patient Specific ◽  
Model Parameters ◽  
Computational Framework ◽  
Lumped Parameter ◽  
Estimation Of Model Parameters

AbstractA major challenge in constructing three dimensional patient specific hemodynamic models is the calibration of model parameters to match patient data on flow, pressure, wall motion, etc. acquired in the clinic. Current workflows are manual and time-consuming. This work presents a flexible computational framework for model parameter estimation in cardiovascular flows that relies on the following fundamental contributions. (i) A Reduced-Order Unscented Kalman Filter (ROUKF) model for data assimilation for wall material and simple lumped parameter network (LPN) boundary condition model parameters. (ii) A constrained least squares augmentation (ROUKF-CLS) for more complex LPNs. (iii) A “Netlist” implementation, supporting easy filtering of parameters in such complex LPNs. The ROUKF algorithm is demonstrated using non-invasive patient-specific data on anatomy, flow and pressure from a healthy volunteer. The ROUKF-CLS algorithm is demonstrated using synthetic data on a coronary LPN. The methods described in this paper have been implemented as part of the CRIMSON hemodynamics software package.

Numerical Simulation of Blood Flow in Patient-Specific Stenotic Carotid Bifurcation Geometries

2009 ◽  
Author(s):  
Megan Cummins ◽  
Jenn S. Rossmann
Keyword(s):  
Vortex Shedding ◽  
Carotid Bifurcation ◽  
Secondary Flows ◽  
Patient Specific ◽  
Mechanical Forces ◽  
Plaque Vulnerability ◽  
Governing Equations ◽  
Unstable Plaque ◽  
Recirculation Zones ◽  
Insight Into

The hemodynamics and fluid mechanical forces in blood vessels have long been implicated in the deposition and growth of atherosclerotic plaque. Detailed information about the hemodynamics in vessels affected by significant plaque deposits can provide insight into the mechanisms and likelihood of plaque weakening and rupture. In the current study, the governing equations are solved in their finite volume formulation in several patient-specific geometries. Recirculation zones, vortex shedding, and secondary flows are captured. The forces on vessel walls are shown to correlate with unstable plaque deposits. The results of these simulations suggest morphological features that may usefully supplement percent stenosis as a predictor of plaque vulnerability.

Abstract TMP29: Prediction of Wall-thinning Area in Unruptured Intracerebral Aneurysms by Computational Fluid Dynamics

Stroke ◽  
2013 ◽  
Vol 44 (suppl_1) ◽  
Author(s):  
Yoshifumi Hayashi ◽  
Takanobu Yagi ◽  
Yasutaka Tobe ◽  
Yuki Iwabuchi ◽  
Momoko Yamanashi ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wall Pressure ◽  
Patient Specific ◽  
Unruptured Aneurysms ◽  
Divergent Flow ◽  
Wall Thinning ◽  
Risk Of Rupture ◽  
Angiographic Data ◽  
Intracerebral Aneurysm

[Background and purpose] During a clipping surgery, an unruptured intracerebral aneurysm often presented a spatially-localized red-colored "wall-thinning" area. The wall thinning was believed to be related with the risk of rupture. The present aim is given to investigate the predictability of a wall thinning area using computational fluid dynamics (CFD). [Method] We chose 16 unruptured aneurysms (12 MCA, 4 ICA) with clipping surgery and 24 wall-thinning areas were detected from the operation video. CFD study was carried out using patient-specific angiographic data. The wall shear stress (WSS) and the wall pressure were evaluated. [Results] The WSS magnitude was found to be uncorrelated with wall thinning. On the other hand, 20 wall-thinning areas (83%) exhibited a presence of “flow impingement”, which was defined to give the spatial variation of the WSS vector to be divergent with the local elevation of the wall pressure. From CFD, 27 flow impingements were detected and classified according to the degree of divergence. Seven impingements are full-divergent and all of them (100%) are located in the wall thinning areas. The remaining 20 impingements were partial-divergent and 13 impingements of them (65%) were located in the wall thinning areas. A classification of full-/partial-divergent flow impingement was statistically significant for the prediction of wall-thinning areas (P<0.01). [Conclusions] The full-divergent flow impingement was found to be a reliable predictor of the wall thinning area in unruptured intracerebral aneurysms. The present results demonstrated the malignant nature of flow impingement for promoting the thinning of aneurysmal walls.

scholarly journals A computational framework for patient-specific surgical planning of type 1 thyroplasty

2021 ◽  
Vol 1 (12) ◽  
pp. 125203
Author(s):  
Mohammadreza Movahhedi ◽  
Biao Geng ◽  
Qian Xue ◽  
Xudong Zheng
Keyword(s):  
Surgical Planning ◽  
Patient Specific ◽  
Computational Framework

scholarly journals Integrated proteogenomic analysis of metastatic thoracic tumors identifies APOBEC mutagenesis and copy number alterations as drivers of proteogenomic tumor evolution and heterogeneity

2018 ◽  
Author(s):  
Nitin Roper ◽  
Shaojian Gao ◽  
Tapan K. Maity ◽  
A. Rouf Banday ◽  
Xu Zhang ◽  
...  
Keyword(s):  
Copy Number ◽  
Thymic Carcinoma ◽  
Patient Specific ◽  
Tumor Evolution ◽  
Copy Number Alterations ◽  
Immune Microenvironment ◽  
Mutation Status ◽  
Whole Exome ◽  
Rapid Autopsy ◽  
Insight Into

ABSTRACTElucidation of the proteogenomic evolution of metastatic tumors may offer insight into the poor prognosis of patients harboring metastatic disease. We performed whole-exome and transcriptome sequencing, copy number alterations (CNA) and mass spectrometry-based quantitative proteomics of 37 lung adenocarcinoma (LUAD) and thymic carcinoma (TC) metastases obtained by rapid autopsy and found evidence of patient-specific, multi-dimensional heterogeneity. Extreme mutational heterogeneity was evident in a subset of patients whose tumors showed increased APOBEC-signature mutations and expression of APOBEC3 region transcripts compared to patients with lesser mutational heterogeneity. TP53 mutation status was associated with APOBEC hypermutators in our cohort and in three independent LUAD datasets. In a thymic carcinoma patient, extreme heterogeneity and increased APOBEC3AB expression was associated with a high-risk germline APOBEC3AB variant allele. Patients with CNA occurring late in tumor evolution had corresponding changes in gene expression and protein abundance indicating genomic instability as a mechanism of downstream transcriptomic and proteomic heterogeneity between metastases. Across all tumors, proteomic heterogeneity was greater than copy number and transcriptomic heterogeneity. Enrichment of interferon pathways was evident both in the transcriptome and proteome of the tumors enriched for APOBEC mutagenesis despite a heterogeneous immune microenvironment across metastases suggesting a role for the immune microenvironment in the expression of APOBEC transcripts and generation of mutational heterogeneity. The evolving, heterogeneous nature of LUAD and TC, through APOBEC-mutagenesis and CNA illustrate the challenges facing treatment outcomes.

Risk Forecast of In-Stent Restenosis by CFD Method

2014 ◽  
Vol 553 ◽  
pp. 235-239
Author(s):  
Chang Yan Lin ◽  
Xiu Jian Liu ◽  
Yu Yang Liu ◽  
Chuang Ye Xu ◽  
Guang Hui Wu
Keyword(s):  
Arterial Wall ◽  
Patient Specific ◽  
Stent Restenosis ◽  
Stent Treatment ◽  
Bifurcation Lesions ◽  
Risk Forecast ◽  
One Year ◽  
Cfd Method ◽  
In Stent Restenosis

The treatment of plaques near and involving coronary bifurcations (CB) is especially challenging, considering more plaques localized these regions and higher post-interventional in-stent restenosis (ISR) risk, mainly due to hemodynamic injury provoked on the arterial wall. Therefore optimization of stenting should begin with an understanding of how disease localized to these regions and why ISR formed associated with flow patterns. We chose four patients with bifurcation lesions, two patients with ISR and two without ISR according to the follow-up computed tomography angiography (CTA). Based on patient-specific pre-interventional and virtual stented geometries from CTA images, numerical simulation indicated that the wall shear stress (WSS) in stented segments, where the ISR occurred in one year, was lower than those without ISR, however. For bifurcation lesion, the stenting segments WSS is supposed a marker to forecast the ISR risk after stent treatment.

Sign in / Sign up

Export Citation Format

Share Document