Blar i NTNU Open på forfatter "Hellevik, Leif Rune"
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3-D Doppler imaging in cardiac applications using high frame-rate sequences
Fiorentini, Stefano (Doctoral theses at NTNU;2020:60, Doctoral thesis, 2020)Several decades after the establishment of Doppler ultrasound, quantification and imaging of blood flow using Doppler-based techniques continue to face multiple challenges. Out-of-plane flow, transit-time broadening and ... -
Arterial Flow and Pulse Wave Propagation in one dimensional Arterial Networks with Statistically Distributed Model Parameters
Eck, Vinzenz Gregor (Master thesis, 2012)Parametric uncertainty in blood flow simulations of cardiovascular systems has received little attention, although methods for blood flow simulation has been subject of many studies. This work presents the implementation ... -
Bond Graph Model of Cerebral Circulation: Toward Clinically Feasible Systemic Blood Flow Simulations
Safaei, Soroush; Blanco, Pablo Javier; Muller, Lucas Omar; Hellevik, Leif Rune; Hunter, Peter J. (Journal article; Peer reviewed, 2018)We propose a detailed CellML model of the human cerebral circulation that runs faster than real time on a desktop computer and is designed for use in clinical settings when the speed of response is important. A lumped ... -
Boundary Conditions for 3D Fluid-Structure Interaction Simulations of Compliant Vessels
Hansen, Merethe Sirevåg (Master thesis, 2013)The goal of this study was to investigate different outlet boundary conditions for a straight compliant tube, by the means of fluid-structure interaction simulations. In addition to investigating boundary conditions it was ... -
Cardiovascular models for personalised medicine: Where now and where next?
Hose, David Rodney; Lawford, Patricia V.; Huberts, Wouter; Hellevik, Leif Rune; Omholt, Stig William; van de Vosse, Frans (Journal article, 2019)The aim of this position paper is to provide a brief overview of the current status of cardiovascular modelling and of the processes required and some of the challenges to be addressed to see wider exploitation in both ... -
Closing the Gap between Reality and CFD Simulations of FFR with Techniques to Quantify and Reduce Uncertainty of Predictions
Nydal, Hallvard Moian; Kjernlie, Johannes Kløve (Master thesis, 2016)Coronary artery disease has been reported the most common cause of death worldwide and is an ever-growing problem for global health. Recently, diagnosis of coronary artery disease from CT angiography (CTA) and computational ... -
Comparison of numerical schemes for nonlinear 1-D arterial blood flow modeling
Fossan, Fredrik Eikeland (Master thesis, 2015)In this Thesis, the numerical methods used in STARFiSh (MacCormack or McC) have been tested and compared with five other state of the art flow-solvers: discontinuous Galerkin (DCG), locally conservative Galerkin (LCG), ... -
Computational Diagnosis of Coronary Artery Disease - A comparison of steady and transient blood flow simulations for FFR
Aamodt, Simen (Master thesis, 2017)An emerging method for non-invasive diagnosis of coronary artery disease is the computational assessment of fractional flow reserve (FFR), a patient normalized physiological index quantifying arterial pressure drop. ... -
Exploring the capabilities of machine learning (ML) for 1D blood flow: Application to coronary flow
Sklet, Vilde (Master thesis, 2018)The aim of this thesis is to explore the capabilities of deep neural networks to reproduce 1D computational models for the pressure in a coronary tree. A machine learning algorithm was implemented. The algorithm was trained ... -
FEM Simluations of Shear Waves in the Heart Wall
Grimsmo, Erik Løhre (Master thesis, 2013)With knowledge of the stiffness of the heart wall, medical personnel can diagnose patients' heart condition. The stiffness of the heart can be altered, e.g. due to a heart attack. New ultrasound technology allows for in ... -
FEM simulations of an Acoustic Radiation Force Impulse applied to a Soft Tissue with a Tumor Inclusion
Dæhli, Lars Edvard (Master thesis, 2013)The elastic stiffness properties of soft tissues can be estimated by the use of locally induced displacements and shear waves. In this work, we have made a two-dimensional plane strain finite element model to simulate a ... -
Finite Element Approximation of the Acoustic Impedance in Transducer Layers Comprising Silver Coated Monodisperse Polymer Spheres in a Polymer Adhesive
Blomvik, Sindre Kongshaug (Master thesis, 2017)In this work, we study the acoustic impedance of Isotropic Conductive Adhesives (ICAs) consisting of silver coated monodisperse polymer spheres. These ICAs are intended to be used as thermal conductive isolation and matching ... -
Fluid Structure Interaction Simulation on an Idealized Aortic Arch
Eeg, Thomas Bertheau (Master thesis, 2012)The aortic arch is at risk of several cardiovascular diseases, such as aortic dissection. Many of these risk factors are due to the fluid-structure interaction that occurs in the aorta. Fluid-structure interation (FSI) ... -
Impact of baseline coronary flow and its distribution on Fractional Flow Reserve prediction
Muller, Lucas Omar; Fossan, Fredrik Eikeland; Bråten, Anders Tjellaug; Jørgensen, Arve; Wiseth, Rune; Hellevik, Leif Rune (Journal article; Peer reviewed, 2019)Model‐based prediction of fractional flow reserve (FFR) in the context of stable coronary artery disease (CAD) diagnosis requires a number of modelling assumptions. One of these assumptions is the definition of a baseline ... -
Numerical Investigation of the Hemodynamics in the Human Fetal Umbilical Vein/ Ductus Venosus Bifurcation
Meland, Elisabeth (Master thesis, 2012)The transport of oxygenated blood from the placenta to the human fetus has received great attention in clinical Doppler velocimetry studies, especially the ductus venosus. The ductus venosus is connecting the intra abdominal ... -
Numeriske beregninger av blodstrømning for diagnostisering av koronarsykdom - En evaluering av én- og tredimensjonal modellering
Nilsen, Stig Marsteng (Master thesis, 2016)Hovedmålet med oppgaven har vært å undersøke metoder for ikke-invasiv diagnostisering av koronarsykdom. Numeriske strømningsberegninger har blitt gjort i én og tre dimensjoner, på geometri funnet i litteraturen og på ... -
Optimization of topological complexity for one-dimensional arterial blood flow models
Fossan, Fredrik Eikeland; Mariscal-Harana, Jorge; Alastruey, Jordi; Hellevik, Leif Rune (Journal article; Peer reviewed, 2018)As computational models of the cardiovascular system are applied in modern personalized medicine, maximizing certainty of model input becomes crucial. A model with a high number of arterial segments results in a more ... -
The Time Varying Elastance Model used as a Boundary Condition in Arterial Network Simulations
Maråk, Knut Petter (Master thesis, 2013)Vascular1Dflow is a program for simulating blood flow in vascular networks. It uses hyperbolic one-dimensional partial differential equations with ordinary differential equations as boundary conditions. The focus of this ... -
Uncertainty propagation through a point model for steady-state two-phase pipe flow
Strand, Andreas; Smith, Ivar Eskerud; Unander, Tor Erling; Steinsland, Ingelin; Hellevik, Leif Rune (Peer reviewed; Journal article, 2020)Uncertainty propagation is used to quantify the uncertainty in model predictions in the presence of uncertain input variables. In this study, we analyze a steady-state point-model for two-phase gas-liquid flow. We present ... -
Uncertainty quantification and sensitivity analysis for cardiovascular models
Eck, Vinzenz Gregor (Doctoral thesis at NTNU;2016:234, Doctoral thesis, 2016)The major challenge for applying cardiovascular models in personalized medicine is as follows: How certain are the predictions of a cardiovascular model, taking the natural variations and measurement uncertainty of model ...