scholarly journals Data Assimilation by Stochastic Ensemble Kalman Filtering to Enhance Turbulent Cardiovascular Flow Data From Under-Resolved Observations

2021 ◽  
Vol 8 ◽  
Author(s):  
Dario De Marinis ◽  
Dominik Obrist
Keyword(s):  
Data Assimilation ◽  
Flow Field ◽  
Turbulent Flows ◽  
Temporal Resolution ◽  
Flow Fields ◽  
Observation Data ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri

We propose a data assimilation methodology that can be used to enhance the spatial and temporal resolution of voxel-based data as it may be obtained from biomedical imaging modalities. It can be used to improve the assessment of turbulent blood flow in large vessels by combining observed data with a computational fluid dynamics solver. The methodology is based on a Stochastic Ensemble Kalman Filter (SEnKF) approach and geared toward pulsatile and turbulent flow configurations. We describe the observed flow fields by a mean value and its covariance. These flow fields are combined with forecasts obtained from a direct numerical simulation of the flow field. The method is validated against canonical pulsatile and turbulent flows. Finally, it is applied to a clinically relevant configuration, namely the flow downstream of a bioprosthetic valve in an aorta phantom. It is demonstrated how the 4D flow field obtained from experimental observations can be enhanced by the data assimilation algorithm. Results show that the presented method is promising for future use with in vivo data from 4D Flow Magnetic Resonance Imaging (4D Flow MRI). 4D Flow MRI returns spatially and temporally averaged flow fields that are limited by the spatial and the temporal resolution of the tool. These averaged flow fields and the associated uncertainty might be used as observation data in the context of the proposed methodology.

scholarly journals Assessment of turbulent blood flow and wall shear stress in aortic coarctation using image-based simulations

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Romana Perinajová ◽  
Joe F. Juffermans ◽  
Jonhatan Lorenzo Mercado ◽  
Jean-Paul Aben ◽  
Leon Ledoux ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Turbulent Flows ◽  
Patient Specific ◽  
4D Flow Mri ◽  
4D Flow ◽  
Local Flow ◽  
Flow Mri ◽  
Wall Shear

AbstractIn this study, we analyzed turbulent flows through a phantom (a 180$$^{\circ }$$ ∘ bend with narrowing) at peak systole and a patient-specific coarctation of the aorta (CoA), with a pulsating flow, using magnetic resonance imaging (MRI) and computational fluid dynamics (CFD). For MRI, a 4D-flow MRI is performed using a 3T scanner. For CFD, the standard $$k-\epsilon $$ k - ϵ , shear stress transport $$k-\omega $$ k - ω , and Reynolds stress (RSM) models are applied. A good agreement between measured and simulated velocity is obtained for the phantom, especially for CFD with RSM. The wall shear stress (WSS) shows significant differences between CFD and MRI in absolute values, due to the limited near-wall resolution of MRI. However, normalized WSS shows qualitatively very similar distributions of the local values between MRI and CFD. Finally, a direct comparison between in vivo 4D-flow MRI and CFD with the RSM turbulence model is performed in the CoA. MRI can properly identify regions with locally elevated or suppressed WSS. If the exact values of the WSS are necessary, CFD is the preferred method. For future applications, we recommend the use of the combined MRI/CFD method for analysis and evaluation of the local flow patterns and WSS in the aorta.

scholarly journals Effect of temporal resolution on 4D flow MRI in the portal circulation

2013 ◽  
Vol 39 (4) ◽  
pp. 819-826 ◽  
Author(s):  
Benjamin R. Landgraf ◽  
Kevin M. Johnson ◽  
Alejandro Roldán-Alzate ◽  
Christopher J. Francois ◽  
Oliver Wieben ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Portal Circulation ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri

Abstract 14534: In vitro Assessment of Transvalvular Peak Velocity Measurement for Various Orifice Shapes: Comparison Between 4D Flow MRI vs. Doppler Echocardiography

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Jeesoo Lee ◽  
Nadia El hangouche ◽  
Liliana Ma ◽  
Michael Scott ◽  
Michael Markl ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Continuous Wave ◽  
Peak Velocity ◽  
Left Ventricular ◽  
Patient Specific ◽  
Maximal Velocity ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Phantom ◽  
Flow Mri

Introduction: 4D flow MRI can assess transvalvular velocity, but validation against continuous wave (CW) Doppler echo is limited in high-velocity regurgitation and stenosis situations. We sought to compare 4D flow MRI and echo peak velocity using a pulsatile echo-MRI flow phantom. Materials and Methods: An MRI-compatible flow phantom with restrictive orifice situated was driven by a left ventricular assist device at 50 bpm (figure 1A). Three orifice shapes were tested: circular, elliptical and 3D-printed patient-specific mitral regurgitant orifice model of prolapse with areas of 0.5, 0.41 and 0.35 cm 2 , respectively. CW Doppler was acquired with peak velocity extracted from the profile. Retrospectively-gated 4D flow MRI was performed (spatial resolution = 2 mm isotropic, temporal resolution = 36 ms, encoding velocity = 400 cm/s). Maximal velocity magnitude was extracted volumetrically (figure 1B). An echo-mimicking profile was also obtained with a “virtual” ultrasound beam in the 4D flow data to simulate CW Doppler (figure 1C). Bland-Altman analysis was used to assess the agreement of temporal peak velocities. Results: 4D flow MRI demonstrated a centrally directed jet for the circular and elliptical orifices and an oblique jet for the prolapse orifice (figure 1B). Peak velocities were in excellent agreement between 4D flow MRI vs. echo for the circular (peak: 5.13 vs. 5.08 m/s, bias = 0.06 ± 0.66 m/s, figure 1D) and the elliptical orifice (peak: 4.95 vs. 4.79 m/s, bias = 0.07 ± 0.87 m/s, figure 1E). The prolapse orifice velocity was underestimated somewhat by MRI by ~10% (peak: 4.41 vs. 4.90 m/s, bias=0.26±1.18, figure 1F). Conclusion: 4D flow MRI can quantify high velocities like echo for simple geometries while underestimating for more complex geometry, likely due to partial volume effects. Further investigation is warranted to systematically investigate the effects of 4D flow MRI spatial and temporal resolution as well as the jet angle on velocity quantification accuracy.

scholarly journals In vivo validation of 4D flow MRI for assessing the hemodynamics of portal hypertension

2013 ◽  
Vol 37 (5) ◽  
pp. spcone-spcone
Author(s):  
Alejandro Roldán-Alzate ◽  
Alex Frydrychowicz ◽  
Eric Niespodzany ◽  
Ben R. Landgraf ◽  
Kevin M. Johnson ◽  
...  
Keyword(s):  
Portal Hypertension ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri ◽  
In Vivo Validation

scholarly journals 1050: Cross-modality, in-vivo validation of 4D-Flow MRI evaluation of uterine artery blood flow in human pregnancy

2019 ◽  
Vol 220 (1) ◽  
pp. S673-S674
Author(s):  
Nadav Schwartz ◽  
Eileen Hwuang ◽  
Ana Rodriguez-Soto ◽  
Felix Wehrli ◽  
Marta Vidorreta ◽  
...  
Keyword(s):  
Blood Flow ◽  
Uterine Artery ◽  
Artery Blood Flow ◽  
4D Flow Mri ◽  
4D Flow ◽  
Human Pregnancy ◽  
Flow Mri ◽  
Mri Evaluation ◽  
In Vivo Validation

scholarly journals Impact of Pulmonary Venous Inflow on Cardiac Flow Simulations: Comparison with In Vivo 4D Flow MRI

2018 ◽  
Vol 47 (2) ◽  
pp. 413-424 ◽  
Author(s):  
Jonas Lantz ◽  
Vikas Gupta ◽  
Lilian Henriksson ◽  
Matts Karlsson ◽  
Anders Persson ◽  
...  
Keyword(s):  
4D Flow Mri ◽  
4D Flow ◽  
Flow Simulations ◽  
Flow Mri

Effect of temporal resolution on 4D flow MRI in the portal circulation

2014 ◽  
Vol 39 (4) ◽  
pp. spcone-spcone ◽  
Author(s):  
Benjamin R. Landgraf ◽  
Kevin M. Johnson ◽  
Alejandro Roldán-Alzate ◽  
Christopher J. Francois ◽  
Oliver Wieben ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Portal Circulation ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri

scholarly journals A dual-VENC 4D Flow MRI Framework for Analysis of Subject-Specific Heterogeneous non-linear Vessel Deformation

2020 ◽  
Author(s):  
Jamie Concannon ◽  
Niamh Hynes ◽  
Marie McMullan ◽  
Evelyn Smyth ◽  
Kevin Mattheus Moerman ◽  
...  
Keyword(s):  
In Silico ◽  
Cardiac Cycle ◽  
Human Aorta ◽  
4D Flow Mri ◽  
4D Flow ◽  
Imaging Protocol ◽  
Subject Specific ◽  
Non Linear ◽  
Flow Mri

Advancement of subject-specific in-silico medicine requires new imaging protocols tailored to specific anatomical features, paired with new constitutive model development based on structure/function relationships. In this study we develop a new dual-VENC 4D Flow MRI protocol that provides unprecedented spatial and temporal resolution of in-vivo aortic deformation. All previous dual-VENC 4D Flow MRI studies in the literature focus on an isolated segment of the aorta, which fail to capture the full spectrum of aortic heterogeneity that exists along the vessel length. The imaging protocol developed provides high sensitivity to all blood flow velocities throughout the entire cardiac cycle, overcoming the challenge of accurately measuring the highly unsteady non-uniform flow field in the aorta. Cross sectional area change, volumetric flow rate, and compliance are observed to decrease with distance from the heart, while pulse wave velocity is observed to increase. A non-linear aortic lumen pressure-area relationship is observed throughout the aorta, such that a high vessel compliance occurs during diastole, and a low vessel compliance occurs during systole. This suggests that a single value of compliance may not accurately represent vessel behaviour during a cardiac cycle in-vivo. This high-resolution MRI data provides key information on the spatial variation in non-linear aortic compliance which can significantly advance the state-of-the-art of in-silico diagnostic techniques for the human aorta.

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