Non-invasive dynamic visualisation of the carotid artery bifurcation in vivo with a three-dimensional optoacoustic hand-held scanner (Conference Presentation)

2018 ◽  
Author(s):  
Ivana Ivankovic ◽  
Elena Mercep ◽  
Xosé Luis Deán-Ben ◽  
Daniel Razansky
Keyword(s):  
Carotid Artery ◽  
Three Dimensional ◽  
Non Invasive ◽  
Carotid Artery Bifurcation

scholarly journals Turbulence Modeling in Three-Dimensional Stenosed Arterial Bifurcations

2006 ◽  
Vol 129 (1) ◽  
pp. 40-50 ◽  
Author(s):  
J. Banks ◽  
N. W. Bressloff
Keyword(s):  
Carotid Artery ◽  
Turbulence Modeling ◽  
Turbulent Viscosity ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Shape Variation ◽  
Severe Stenosis ◽  
Carotid Artery Bifurcation ◽  
Inflow Turbulence ◽  
Flow Through

Under normal healthy conditions, blood flow in the carotid artery bifurcation is laminar. However, in the presence of a stenosis, the flow can become turbulent at the higher Reynolds numbers during systole. There is growing consensus that the transitional k−ω model is the best suited Reynolds averaged turbulence model for such flows. Further confirmation of this opinion is presented here by a comparison with the RNG k−ϵ model for the flow through a straight, nonbifurcating tube. Unlike similar validation studies elsewhere, no assumptions are made about the inlet profile since the full length of the experimental tube is simulated. Additionally, variations in the inflow turbulence quantities are shown to have no noticeable affect on downstream turbulence intensity, turbulent viscosity, or velocity in the k−ϵ model, whereas the velocity profiles in the transitional k−ω model show some differences due to large variations in the downstream turbulence quantities. Following this validation study, the transitional k−ω model is applied in a three-dimensional parametrically defined computer model of the carotid artery bifurcation in which the sinus bulb is manipulated to produce mild, moderate, and severe stenosis. The parametric geometry definition facilitates a powerful means for investigating the effect of local shape variation while keeping the global shape fixed. While turbulence levels are generally low in all cases considered, the mild stenosis model produces higher levels of turbulent viscosity and this is linked to relatively high values of turbulent kinetic energy and low values of the specific dissipation rate. The severe stenosis model displays stronger recirculation in the flow field with higher values of vorticity, helicity, and negative wall shear stress. The mild and moderate stenosis configurations produce similar lower levels of vorticity and helicity.

Three‐dimensional quantitative T 1 and T 2 mapping of the carotid artery: Sequence design and in vivo feasibility

2016 ◽  
Vol 75 (3) ◽  
pp. 1008-1017 ◽  
Author(s):  
Bram F. Coolen ◽  
Dirk H.J. Poot ◽  
Madieke I. Liem ◽  
Loek P. Smits ◽  
Shan Gao ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Three Dimensional ◽  
Sequence Design

In Vivo Blood Velocity Vector Imaging Using Adaptive Velocity Compounding in the Carotid Artery Bifurcation

2019 ◽  
Vol 45 (7) ◽  
pp. 1691-1707 ◽  
Author(s):  
Anne E.C.M. Saris ◽  
Hendrik H.G. Hansen ◽  
Stein Fekkes ◽  
Jan Menssen ◽  
Maartje M. Nillesen ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Velocity Vector ◽  
Blood Velocity ◽  
Carotid Artery Bifurcation ◽  
Velocity Vector Imaging

scholarly journals Non-Invasive Quantification of the Growth of Cancer Cell Colonies by a Portable Optical Coherence Tomography

Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 35 ◽  
Author(s):  
Meng-Tsan Tsai ◽  
Bo-Huei Huang ◽  
Chun-Chih Yeh ◽  
Kin Fong Lei ◽  
Ngan-Ming Tsang
Keyword(s):  
Optical Coherence Tomography ◽  
Cancer Cell ◽  
Cellular Response ◽  
Tumor Development ◽  
Three Dimensional ◽  
Cancer Cell Line ◽  
Optical Coherence ◽  
Non Invasive

Investigation of tumor development is essential in cancer research. In the laboratory, living cell culture is a standard bio-technology for studying cellular response under tested conditions to predict in vivo cellular response. In particular, the colony formation assay has become a standard experiment for characterizing the tumor development in vitro. However, quantification of the growth of cell colonies under a microscope is difficult because they are suspended in a three-dimensional environment. Thus, optical coherence tomography (OCT) imaging was develop in this study to monitor the growth of cell colonies. Cancer cell line of Huh 7 was used and the cells were applied on a layer of agarose hydrogel, i.e., a non-adherent surface. Then, cell colonies were gradually formed on the surface. The OCT technique was used to scan the cell colonies every day to obtain quantitative data for describing their growth. The results revealed the average volume increased with time due to the formation of cell colonies day-by-day. Additionally, the distribution of cell colony volume was analyzed to show the detailed information of the growth of the cell colonies. In summary, the OCT provides a non-invasive quantification technique for monitoring the growth of the cell colonies. From the OCT images, objective and precise information is obtained for higher prediction of the in vivo tumor development.

scholarly journals Choice of In Vivo Versus Idealized Velocity Boundary Conditions Influences Physiologically Relevant Flow Patterns in a Subject-Specific Simulation of Flow in the Human Carotid Bifurcation

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Amanda K. Wake ◽  
John N. Oshinski ◽  
Allen R. Tannenbaum ◽  
Don P. Giddens
Keyword(s):  
Carotid Artery ◽  
Boundary Conditions ◽  
Carotid Bifurcation ◽  
Flow Patterns ◽  
Flow Data ◽  
Measured Velocity ◽  
Carotid Artery Bifurcation ◽  
Subject Specific ◽  
Human Carotid

Accurate fluid mechanics models are important tools for predicting the flow field in the carotid artery bifurcation and for understanding the relationship between hemodynamics and the initiation and progression of atherosclerosis. Clinical imaging modalities can be used to obtain geometry and blood flow data for developing subject-specific human carotid artery bifurcation models. We developed subject-specific computational fluid dynamics models of the human carotid bifurcation from magnetic resonance (MR) geometry data and phase contrast MR velocity data measured in vivo. Two simulations were conducted with identical geometry, flow rates, and fluid parameters: (1) Simulation 1 used in vivo measured velocity distributions as time-varying boundary conditions and (2) Simulation 2 used idealized fully-developed velocity profiles as boundary conditions. The position and extent of negative axial velocity regions (NAVRs) vary between the two simulations at any given point in time, and these regions vary temporally within each simulation. The combination of inlet velocity boundary conditions, geometry, and flow waveforms influences NAVRs. In particular, the combination of flow division and the location of the velocity peak with respect to individual carotid geometry landmarks (bifurcation apex position and the departure angle of the internal carotid) influences the size and location of these reversed flow zones. Average axial wall shear stress (WSS) distributions are qualitatively similar for the two simulations; however, instantaneous WSS values vary with the choice of velocity boundary conditions. By developing subject-specific simulations from in vivo measured geometry and flow data and varying the velocity boundary conditions in otherwise identical models, we isolated the effects of measured versus idealized velocity distributions on blood flow patterns. Choice of velocity distributions at boundary conditions is shown to influence pathophysiologically relevant flow patterns in the human carotid bifurcation. Although mean WSS distributions are qualitatively similar for measured and idealized inlet boundary conditions, instantaneous NAVRs differ and warrant imposing in vivo velocity boundary conditions in computational simulations. A simulation based on in vivo measured velocity distributions is preferred for modeling hemodynamics in subject-specific carotid artery bifurcation models when studying atherosclerosis initiation and development.

A novel non-invasive method for estimating the local wave speed at a single site in the internal carotid artery

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Asma Ayadi ◽  
Wassila Sahtout ◽  
Olivier Baledent
Keyword(s):  
Carotid Artery ◽  
Internal Carotid Artery ◽  
Wave Speed ◽  
Internal Carotid ◽  
Blood Velocity ◽  
Non Invasive ◽  
Velocity Waveform ◽  
Local Wave ◽  
Invasive Method

AbstractObjectivesLocal wave speed is a biomarker which provides an objective analysis of the cardiovascular function. The aim of this study was to determine the local wave speed in the internal carotid artery by a new non-invasive method that measures blood velocity waveform at only one site.MethodsFor this purpose, the cepstral analysis was employed to determine the arrival time of the reflection wave and the wave speed in the carotid artery. To validate our model, we applied it experimentally in vivo on young and old healthy subjects. The blood velocity waveform was measured by using phase-contrast magnetic resonance for 22 subjects.ResultsOur experimental results correlated with reference values reported in previous studies conducted on the internal arterial carotid usually adopting the invasive method. They also correlated with those obtained by using the foot-to-foot method (R2=0.72). The wave speed obtained by the method developed in this study and that of the foot-to-foot method increased with age (p<0.001).ConclusionsThe method developed in this study can be applied in the other arteries and it can also be used with other techniques such as ultrasound imaging.

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