A5068821754- Advanced MRI Techniques and Applications
- Advanced Mathematical Modeling in Engineering
- Composite Material Mechanics
- Advanced Numerical Methods in Computational Mathematics
- Numerical methods in engineering
- Elasticity and Material Modeling
- Cardiac Valve Diseases and Treatments
- Cardiovascular Function and Risk Factors
- MRI in cancer diagnosis
- Aortic Disease and Treatment Approaches
- Cardiac Imaging and Diagnostics
- NMR spectroscopy and applications
- Advanced Neuroimaging Techniques and Applications
- Cardiovascular Health and Disease Prevention
- Numerical methods in inverse problems
- Ultrasound Imaging and Elastography
- Medical Image Segmentation Techniques
- Coronary Interventions and Diagnostics
- Photoacoustic and Ultrasonic Imaging
- Electromagnetic Simulation and Numerical Methods
- Image and Signal Denoising Methods
- Cellular Mechanics and Interactions
- Model Reduction and Neural Networks
- Ultrasound and Hyperthermia Applications
- Shoulder and Clavicle Injuries
Federico Santa María Technical University
2020-2025
Universidad Técnica Federico Santa María
2023
Millennium Science Initiative
2020-2022
Pontificia Universidad Católica de Chile
2001-2021
Agencia Nacional de Investigación y Desarrollo
2021
Ministry of Economy, Development and Tourism
2019
Pontificia Universidad Católica de Valparaíso
2011-2016
Purpose To decompose the 3D wall shear stress (WSS) vector field into its axial (WSS A ) and circumferential C components using a Laplacian finite element approach. Methods We validated our method with in silico experiments involving different geometries modified Poiseuille flow. computed maps of WSS, WSS , 4D flow MRI data obtained from 10 volunteers patients bicuspid aortic valve (BAV). compared centerline method. The mean value, standard deviation, root mean‐squared error, Wilcoxon signed...
Purpose We propose a 3D finite‐element method for the quantification of vorticity and helicity density from cine phase‐contrast (PC) MRI. Methods By using method, we seamlessly estimate velocity gradients in 3D. The robustness convergence were analyzed combined Poiseuille Lamb‐Ossen equation. A computational fluid dynamics simulation was used to compared our with others available literature. Additionally, computed maps different PC‐MRI data sets: phantom without coarctation (18 healthy...
Purpose Magnetic resonance elastography (MRE) measures stiffness of soft tissues by analyzing their spatial harmonic response to externally induced shear vibrations. Many MRE methods use inversion‐based reconstruction approaches, which invoke first‐ or second‐order derivatives finite difference operators (first‐ and second‐FDOs) thus give rise a biased frequency dispersion estimates. Methods We here demonstrate analytically, numerically, experimentally that FDO‐based estimates are affected...
In this paper we study the Brinkman model as a unified framework to allow transition between Darcy and Stokes problems. We propose an unconditionally stable low-order finite element approach, which is robust with respect whole range of physical parameters, based on combination stabilized equal-order elements non-symmetric penalty-free Nitsche method for weak imposition essential boundary conditions. particular, properties formulation setting, extending recently reported analysis case...
Velocity measurements from 4D flow MRI are prone to be affected by several imperfections of the MR system. Assuming that blood is incompressible, we propose a novel method for enhancing velocity field reducing its divergence. To enhance data, added corrector each voxel such divergence minimized. The was validated using an analytical Womersley model different settings resolution and noise levels. performance proposed also assessed in volunteers patients. Results demonstrated significant...
Background and Purpose Prognostic models based on cardiovascular hemodynamic parameters may bring new information for an early assessment of patients with bicuspid aortic valve (BAV), playing a key role in reducing the long-term risk events. This work quantifies several three-dimensional different BAV ranks their relationships diameter. Materials Methods Using 4D-flow CMR data 74 (49 right-left 25 right-non-coronary) 48 healthy volunteers, 3D maps seventeen 17 were quantified along thoracic...
We study limit cycles of nonlinear oscillators described by the equation x + nuF(x) = 0 with F an odd function. Depending on nonlinearity, this may exhibit one or more cycles. show that correspond to relative extrema a certain functional. Analytical results in limits nu-->0 and nu-->infinity are agreement previously known criteria. For intermediate nu, numerical determination can be obtained.
This article is devoted to the detection of inclusions using a single boundary measurement obtained from quasi-static essays in linear elasticity. The idea minimize misfit between displacement field on part and data coming solving elasticity equations with guess inclusion. optimization algorithm comes work Allaire Gutiérrez [G. S. Gutiérrez, Optimal design small amplitude homogenization, Math. Model. Numer. Anal. 41(3) (2007), pp. 543–574] it based assumption that contrast values Lamé...
This paper is devoted to the modeling of elastic materials composed an incompressible matrix and small compressible gaseous inclusions, under a time harmonic excitation. In biomedical context, this model describes dynamics biological tissue (e.g., lung) when wave analysis methods (such as magnetic resonance elastography) are used estimate properties. Due multiscale nature problem, direct numerical simulations prohibitive. We extend homogenized introduced in [L. Baffico et al., Multiscale...
We proposed a novel method called HARP-I, which enhances the estimation of motion from tagged Magnetic Resonance Imaging (MRI). The harmonic phase images is unwrapped and treated as noisy measurements reference coordinates on deformed domain, obtaining with high accuracy using Radial Basis Functions interpolations. Results were compared against Shortest Path HARP Refinement (SP-HR) Sine-wave Modeling (SinMod), two image-based techniques for images. HARP-I showed favorable similarity both...
4D Flow Magnetic Resonance Imaging (MRI) is the state-of-the-art technique to comprehensively measure complex spatio-temporal and multidirectional patterns of blood flow. However, it subject artifacts such as noise aliasing, which due 3D dynamic structure difficult detect in clinical practice. In this work, a new mathematical computational model determine quality MRI presented. The derived by assuming true velocity satisfies incompressible Navier-Stokes equations that can be decomposed...
4D flow MRI suffers from different sources of noise and aliasing artifacts. Recent denoising techniques are time-consuming or dependent parameter estimation. We developed a physics informed neural network with divergence-free vector potential as non-parametric technique for MRI. Results simulated pulsatile CFD vascular model shows significant reduction correction. Future work includes comparison other on types data uncertainty quantification.
This work focuses on the numerical solution of dynamics a poroelastic material in frequency domain. We provide detailed stability analysis based application Fredholm alternative continuous case, considering total pressure formulation Biot's equations. In discrete setting, we propose stabilized equal order finite element method complemented by an additional stabilization to enhance robustness scheme with respect fluid permeability. Utilizing alternative, extend well-posedness results...
Motivation: 4D flow MRI suffers from different sources of noise and aliasing artifacts. However, the existing techniques for enhancing velocities in encounter reliability problems with varying patterns or acquisition parameters. Goal(s): Our goal was to develop a velocity enhancement an anti-aliasing technique Flow that can be easily applied diverse types. Approach: We incorporate vector potential into neural network predict fields strictly adhere divergence-free condition. Results: Results...
Abstract Rapid mapping of the mechanical properties soft biological tissues from light microscopy to macroscopic imaging can transform fundamental biophysical research by providing clinical biomarkers complement in vivo elastography. This work introduces superfast optical multifrequency time‐harmonic elastography (OMTHE) remotely encode surface and subsurface shear wave fields for generating maps tissue stiffness with unprecedented detail resolution. OMTHE rigorously exploits space‐time...
To improve the quality of mean apparent propagator (MAP) reconstruction from a limited number q-space samples.We implement an ℓ1 -regularised MAP (MAPL1) to consider higher order basis functions and fit without increasing samples. We compare MAPL1 with least-squares optimization subject non-negativity (MAP), Laplacian-regularized (MAPL). use simulations crossing fibers compute normalized squared error (NMSE) Pearson's correlation coefficient evaluate in q-space. also coefficient-based...