Study of Extracted Geometry Effect on Patient-Specific Cerebral Aneurysm Model with Different Threshold Coefficient (Cthres)

The recent diagnostic assessment of cerebrovascular disease makes use of computational fluid dynamics (CFD) to quantify blood flow and determine the hemodynamics factors contributing to the disease from patient-specific models. However, compliant and anatomical patient-specific geometries are generally reconstructed from the medical images with different threshold values subjectively. Therefore, this paper tends to present the effect of extracted geometry with different threshold coefficient, Cthres by using a patient-specific cerebral aneurysm model. A set of medical images, digital subtraction angiography (DSA) images from the real patient diagnosed with internal carotid artery (ICA) aneurysm was obtained. The threshold value used to extract the patient-specific cerebral aneurysm geometry was calculated by using a simple threshold determination method. Several threshold coefficients, Cthres such as 0.2, 0.3, 0.4, 0.5 and 0.6 were employed in the image segmentation creating three-dimensional (3D) realistic arterial geometries that were then used for CFD simulation. As a result, we obtained that the volume of patient-specific cerebral aneurysm geometry decreases as the threshold coefficient, Cthres increases. There is dislocation of artery attached to the ICA aneurysm geometry occurred at a high threshold coefficient, Cthres. Besides, the physical changes also bring remarkable physiological effect on the wall shear stress (WSS) distribution and velocity flow field at patient-specific cerebral aneurysm geometry reconstructed with different threshold coefficient, Cthres.

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Validation of CFD Simulations of Cerebral Aneurysms With Implication of Geometric Variations

Journal of Biomechanical Engineering ◽

10.1115/1.2354209 ◽

2006 ◽

Vol 128 (6) ◽

pp. 844-851 ◽

Cited By ~ 102

Author(s):

Yiemeng Hoi ◽

Scott H. Woodward ◽

Minsuok Kim ◽

Dale B. Taulbee ◽

Hui Meng

Keyword(s):

Flow Field ◽

Cfd Simulation ◽

Three Dimensional ◽

Cerebral Aneurysms ◽

Patient Specific ◽

Hemodynamic Parameters ◽

Cfd Simulations ◽

Piv Measurements ◽

Cfd Method ◽

Aneurysm Model

Background. Computational fluid dynamics (CFD) simulations using medical-image-based anatomical vascular geometry are now gaining clinical relevance. This study aimed at validating the CFD methodology for studying cerebral aneurysms by using particle image velocimetry (PIV) measurements, with a focus on the effects of small geometric variations in aneurysm models on the flow dynamics obtained with CFD. Method of Approach. An experimental phantom was fabricated out of silicone elastomer to best mimic a spherical aneurysm model. PIV measurements were obtained from the phantom and compared with the CFD results from an ideal spherical aneurysm model (S1). These measurements were also compared with CFD results, based on the geometry reconstructed from three-dimensional images of the experimental phantom. We further performed CFD analysis on two geometric variations, S2 and S3, of the phantom to investigate the effects of small geometric variations on the aneurysmal flow field. Results. We found poor agreement between the CFD results from the ideal spherical aneurysm model and the PIV measurements from the phantom, including inconsistent secondary flow patterns. The CFD results based on the actual phantom geometry, however, matched well with the PIV measurements. CFD of models S2 and S3 produced qualitatively similar flow fields to that of the phantom but quantitatively significant changes in key hemodynamic parameters such as vorticity, positive circulation, and wall shear stress. Conclusion. CFD simulation results can closely match experimental measurements as long as both are performed on the same model geometry. Small geometric variations on the aneurysm model can significantly alter the flow-field and key hemodynamic parameters. Since medical images are subjected to geometric uncertainties, image-based patient-specific CFD results must be carefully scrutinized before providing clinical feedback.

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Evaluation of Spherical Parameterization Methods for Three-Dimensional Reconstruction of Medical Images

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.365-366.1342 ◽

2013 ◽

Vol 365-366 ◽

pp. 1342-1349

Author(s):

Xing Hui Wu ◽

Zhi Xiu Hao

Keyword(s):

Medical Images ◽

Three Dimensional ◽

3D Models ◽

Mapping Method ◽

Geometric Error ◽

Patient Specific ◽

Shape Modelling ◽

Dimensional Reconstruction ◽

Statistical Shape ◽

Spherical Parameterization

The spherical parameterization is important for the correspondence problem that is a major part of statistical shape modelling for the reconstruction of patient-specific 3D models from medical images. In this paper, we present comparative studies of five common spherical mapping methods applied to the femur and tibia models: the Issenburg et al. method, the Alexa method, the Saba et al. method, the Praun et al. method and the Shen et al. method. These methods are evaluated using three sets of measures: distortion property, geometric error and distance to standard landmarks. Results show that the Praun et al. method performs better than other methods while the Shen et al. method can be regarded as the most reliable one for providing an acceptable correspondence result. We suggest that the area preserving property can be used as a sufficient condition while the angle preserving property is not important when choosing a spherical mapping method for correspondence application.

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Computational Analyses of an In-Vitro Aneurysm Model Based on Three-Dimensional Angiography With Comparison to Phase Contrast Magnetic Resonance Imaging and Dye Injection Studies

ASME 2010 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2010-19615 ◽

2010 ◽

Author(s):

Stephanie M. George ◽

Pierre Watson ◽

John N. Oshinski ◽

Charles W. Kerber ◽

Daniel Karolyi ◽

...

Keyword(s):

High Speed ◽

Phase Contrast ◽

Cfd Simulation ◽

Fluid Dynamic ◽

Three Dimensional ◽

Cerebral Aneurysms ◽

Computational Fluid Dynamic Simulation ◽

Poor Correlation ◽

Aneurysm Model

Computational fluid dynamic simulation (CFD) is a valuable tool that has been used to understand some of the fundamental conditions of cerebrovascular flow. Current methods include anatomic modeling of cerebral aneurysms derived from vascular imaging such as MRA, CTA, and three-dimensional angiography. The input blood flow waveforms can be represented from either mathematical models or physiologic sampling of flow with phase contrast MR techniques or particle image velocimetry (1). While there has been general acceptance of the validity of computational fluid dynamics, some research suggests that there can be poor correlation between CFD flow calculations and directly measured flow (2). Therefore, the purpose of this study is to qualitatively compare flow patterns in a cerebral aneurysm model using data derived from three sources: (i) direct phase contrast MRA measurement in the model; (ii) CFD simulation using computer models created from three dimensional angiography, and (iii) previously published high speed injection dye studies.

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Reconstruction of Patient-Specific Cerebral Aneurysm Model Through Image Segmentation

Lecture Notes in Mechanical Engineering - Intelligent Manufacturing and Mechatronics ◽

10.1007/978-981-16-0866-7_16 ◽

2021 ◽

pp. 207-214

Author(s):

Sheh Hong Lim ◽

Mohd Azrul Hisham Mohd Adib ◽

Mohd Shafie Abdullah ◽

Nur Hartini Mohd Taib ◽

Radhiana Hassan ◽

...

Keyword(s):

Image Segmentation ◽

Cerebral Aneurysm ◽

Patient Specific ◽

Aneurysm Model

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A multi-modal data model for morphological segmentation in 3D dosimetry

Proceedings of the 8th International Workshop on Innovative Simulation for Healthcare (IWISH 2019) ◽

10.46354/i3m.2019.iwish.004 ◽

2019 ◽

Author(s):

Werner Backfrieder

Keyword(s):

Three Dimensional ◽

Dose Calculation ◽

User Interaction ◽

Image Features ◽

Whole Body ◽

Patient Specific ◽

Clinical Workflow ◽

Real Patient ◽

Radio Therapy ◽

Principal Axes

"Patient specific dosimetry established during the last decade in modern radio-therapy. Usually, tracer kinetics in main compartments of observed metabolism is assessed from anterior and posterior whole body scans. The effective doses for each organ, derived by the MIRD scheme, provide evidence for following radiotherapeutic treatment and helps to meet vital dose limits for critical organs, e.g. kidneys. The calculation of individual dose in a three-dimensional context leads to more accurate dose estimates, as was proven by intensive research, but is still on the cusp to clinical application. In this work, a statistical approach, based on multi-modal image and feature data, is presented, to overcome manual segmentation, the most time consuming step, in 3D based dose calculation. 3D data volumes from a hybrid SPECT study, comprising SPECT and CT data, covering main compartments of metabolism, build the image features of a Gaussian classifier. From prior segmentations organspecific membership maps are derived, and substituted as additional feature into the segmentation procedure. Centroids, eccentricity and principal axes of organ models are registered to a rough thresholded image of the SPECT component, and define membership coefficients of the voxels. The new approach yields accurate results, even with real patient data. The new method needs minimal user interaction during selection of some sample regions, thus showing high potential for implementation in a clinical workflow."

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Modeling three-dimensional-printed trabecular metal structures with a homogenization approach: Application to hemipelvis reconstruction

The International Journal of Artificial Organs ◽

10.1177/0391398819848001 ◽

2019 ◽

Vol 42 (10) ◽

pp. 575-585

Author(s):

Luigi La Barbera ◽

Milena Trabace ◽

Giancarlo Pennati ◽

José Félix Rodríguez Matas

Keyword(s):

Asymptotic Expansion ◽

Mechanical Response ◽

Three Dimensional ◽

Experimental Tests ◽

Design Parameters ◽

Patient Specific ◽

Real Patient ◽

Three Dimensional Printing ◽

Homogenization Approach ◽

Dimensional Printing

The application of three-dimensional printing technologies to metal materials allows us to design innovative, low-weight, patient-specific implants for orthopedic prosthesis. This is particularly true when the reconstruction of extensive metastatic bone defect is planned. Modeling complex three-dimensional-printed highly repetitive trabecular-like structures based on finite elements is computationally demanding, while homogenization algorithms offer the advantage of reduced simulation cost and time, allowing an effective evaluation of new personalized design suitable for clinical needs. This article describes and discusses the implementation of a reliable method for the multiscale modeling of trabecular structures by means of asymptotic expansion homogenization. Following the material characterization of the Ti6Al4V alloy obtained by electron beam melting technology, the asymptotic expansion homogenization was applied to two alternative low-density cell-unit designs. Model predictions demonstrated satisfactory agreement with compressive experimental tests and cantilever bending tests performed on both designs (differences lower than 5.5%). The method was extended to a real patient-specific hemipelvis reconstruction, exploiting the capability of the asymptotic expansion homogenization approach in quantitatively describing the effect of cell-unit designs and three-dimensional-printing stack direction (i.e. cell-unit orientation) both on the overall mechanical response of the implant and on the stress distribution. The hemipelvis implant filled with the higher density cell unit demonstrated to be 14% stiffer than using the lower density one, while changing the cell-unit orientation affected the stiffness up to 10%. The maximum stress values reached at the anchors were affected in a minor extent by the investigated design parameters.

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Direct Structured Finite Element Mesh Generation From Three-Dimensional Medical Images

Volume 1A: Abdominal Aortic Aneurysms; Active and Reactive Soft Matter; Atherosclerosis; BioFluid Mechanics; Education; Biotransport Phenomena; Bone, Joint and Spine Mechanics; Brain Injury; Cardiac Mechanics; Cardiovascular Devices, Fluids and Imaging; Cartilage and Disc Mechanics; Cell and Tissue Engineering; Cerebral Aneurysms; Computational Biofluid Dynamics; Device Design, Human Dynamics, and Rehabilitation; Drug Delivery and Disease Treatment; Engineered Cellular Environments ◽

10.1115/sbc2013-14704 ◽

2013 ◽

Author(s):

Sharareh Bayat ◽

Dan Necsulescu ◽

Michel Labrosse

Keyword(s):

Finite Element ◽

Mesh Generation ◽

Medical Images ◽

Three Dimensional ◽

Finite Element Mesh ◽

Patient Specific ◽

Human Aorta ◽

Element Mesh ◽

Future Directions ◽

Finite Element Mesh Generation

In this work, a new methodology is proposed to automatically construct a structured finite element (FE) mesh from the information contained in patient-specific three-dimensional (3-D) images. Testing of the methodology is presented toward meshing of the human aorta from 3-D synthetic images as well as CT medical images. Promising results are obtained and future directions are discussed.

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SENSITIVITY ANALYSIS OF COMPUTATIONAL STRUCTURAL DYNAMICS IN A CEREBRAL ANEURYSM MODEL TO WALL THICKNESS AND MODEL

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519411004630 ◽

2012 ◽

Vol 12 (03) ◽

pp. 1250054 ◽

Cited By ~ 1

Author(s):

ALVARO VALENCIA ◽

MAXIMILIANO ROJO ◽

RODRIGO RIVERA ◽

EDUARDO BRAVO

Keyword(s):

Cerebral Aneurysm ◽

Structural Dynamics ◽

Wall Thickness ◽

Three Dimensional ◽

Image Data ◽

Realistic Model ◽

Aneurysm Wall ◽

Computational Structural Dynamics ◽

Different Thickness ◽

Aneurysm Model

Intracranial saccular aneurysms tend to be thin walled and stiffer compared with a normal artery. The current work describes computational structural dynamics (CSD) in an anatomically realistic model of a cerebral aneurysm located in the ophthalmic region, using different wall thickness, model data for the artery and aneurysm, and geometry size. The model was obtained from three-dimensional rotational angiography image data. The wall was assumed three-dimensional hyperelastic solid with different thickness in the artery and in the aneurysm regions. The effects of carotid siphon length are reported. The CSD was solved with the finite elements package ADINA. The predictions of stress and strain on the aneurysm wall were compared.

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