scholarly journals In-vitro and In-Vivo Assessment of 4D Flow MRI Reynolds Stress Mapping for Pulsatile Blood Flow

2021 ◽  
Vol 9 ◽  
Author(s):  
Hojin Ha ◽  
Hyung Kyu Huh ◽  
Kyung Jin Park ◽  
Petter Dyverfeldt ◽  
Tino Ebbers ◽  
...  
Keyword(s):  
Blood Flow ◽  
Reynolds Stress ◽  
Normal Subjects ◽  
Interventional Treatment ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri ◽  
Turbulence Analysis

Imaging hemodynamics play an important role in the diagnosis of abnormal blood flow due to vascular and valvular diseases as well as in monitoring the recovery of normal blood flow after surgical or interventional treatment. Recently, characterization of turbulent blood flow using 4D flow magnetic resonance imaging (MRI) has been demonstrated by utilizing the changes in signal magnitude depending on intravoxel spin distribution. The imaging sequence was extended with a six-directional icosahedral (ICOSA6) flow-encoding to characterize all elements of the Reynolds stress tensor (RST) in turbulent blood flow. In the present study, we aimed to demonstrate the feasibility of full RST analysis using ICOSA6 4D flow MRI under physiological conditions. First, the turbulence analysis was performed through in vitro experiments with a physiological pulsatile flow condition. Second, a total of 12 normal subjects and one patient with severe aortic stenosis were analyzed using the same sequence. The in-vitro study showed that total turbulent kinetic energy (TKE) was less affected by the signal-to-noise ratio (SNR), however, maximum principal turbulence shear stress (MPTSS) and total turbulence production (TP) had a noise-induced bias. Smaller degree of the bias was observed for TP compared to MPTSS. In-vivo study showed that the subject-variability on turbulence quantification was relatively low for the consistent scan protocol. The in vivo demonstration of the stenosis patient showed that the turbulence analysis could clearly distinguish the difference in all turbulence parameters as they were at least an order of magnitude larger than those from the normal subjects.

scholarly journals A pilot study investigating the use of 4D flow MRI for the assessment of splanchnic flow in patients suspected of mesenteric ischaemia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pauline Hall Barrientos ◽  
Katrina Knight ◽  
Douglas Black ◽  
Alexander Vesey ◽  
Giles Roditi
Keyword(s):  
Blood Flow ◽  
Pilot Study ◽  
Splenic Vein ◽  
Normal Subjects ◽  
Mesenteric Ischaemia ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri ◽  
Mesenteric Vessels ◽  
Flow Changes

AbstractThe most common cause of chronic mesenteric ischaemia is atherosclerosis which results in limitation of blood flow to the gastrointestinal tract. This pilot study aimed to evaluate 4D flow MRI as a potential tool for the analysis of blood flow changes post-prandial within the mesenteric vessels. The mesenteric vessels of twelve people were scanned; patients and healthy volunteers. A baseline MRI scan was performed after 6 h of fasting followed by a post-meal scan. Two 4D flow datasets were acquired, over the superior mesenteric artery (SMA) and the main portal venous vessels. Standard 2D time-resolved PC-MRI slices were also obtained across the aorta above the coeliac trunk, superior mesenteric vein, splenic vein and portal vein (PV). In the volunteer cohort there was a marked increase in blood flow post-meal within the PV (p = 0.028), not seen in the patient cohort (p = 0.116). Similarly, there were significant flow changes within the SMA of volunteers (p = 0.028) but not for the patient group (p = 0.116). Our pilot data has shown that there is a significant haemodynamic response to meal challenge in the PV and SMA in normal subjects compared to clinically apparent CMI patients. Therefore, the interrogation of mesenteric venous vessels exclusively is a feasible method to measure post-prandial flow changes in CMI patients.

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 Hemodynamic study of TCPC using in vivo and in vitro 4D Flow MRI and numerical simulation

2015 ◽  
Vol 48 (7) ◽  
pp. 1325-1330 ◽  
Author(s):  
Alejandro Roldán-Alzate ◽  
Sylvana García-Rodríguez ◽  
Petros V. Anagnostopoulos ◽  
Shardha Srinivasan ◽  
Oliver Wieben ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri ◽  
Hemodynamic Study

Quantification of Retrograde Blood Flow in the Descending Aorta Using Transesophageal Echocardiography in Comparison to 4D Flow MRI

2015 ◽  
Vol 39 (5-6) ◽  
pp. 287-292 ◽  
Author(s):  
Thomas Wehrum ◽  
Miriam Kams ◽  
Felix Günther ◽  
Primrose Beryl ◽  
Werner Vach ◽  
...  
Keyword(s):  
Blood Flow ◽  
Transesophageal Echocardiography ◽  
Threshold Value ◽  
Retrograde Flow ◽  
4D Flow Mri ◽  
4D Flow ◽  
Descending Aorta ◽  
Flow Mri ◽  
The Mean

Background: Retrograde diastolic blood flow in the proximal descending aorta (DAo), which connects plaques ≥4 mm thickness with brain-supplying arteries, has previously been identified as a possible source of brain embolism. Currently, only 4D flow MRI is able to visualize and quantify potential retrograde embolization pathways in the DAo in-vivo. Hence, it was our aim to test if the extent of retrograde flow could be estimated by routine 2D transesophageal echocardiography (TEE). Methods: Forty-eight acute stroke patients were prospectively included and they underwent Doppler examinations of the transition zone between the aortic arch and the DAo using a 20 mm 2D sample volume in longitudinal section at 90-140° Doppler angle during routine TEE. Velocity-time-integrals (VTI) were studied for antegrade and retrograde velocities and the ratio (VTIratio) was calculated and correlated with the length of retrograde pathlines at that site, which were visualized using 4D flow MRI at 3-Tesla. A receiver operating characteristic (ROC) curve was used to evaluate a threshold value of VTIratio in differentiating large (≥3 cm) from small (<3 cm) retrograde flow extent. Results: At the TEE measurement site, the mean VTIratio was 0.53 ± 0.16 and the mean length of retrograde pathlines reaching back into the aortic arch was 3.1 ± 1.4 cm. VTIratio was an independent predictor of retrograde pathline length (r = 0.44; p = 0.002). ROC analysis identified a VTIratio threshold value of 0.6012 with a sensitivity of 0.5, a specificity of 0.92, and positive and negative predictive values of 0.84 and 0.68, respectively. Accordingly, 11 (22.91%) patients had a VTIratio cutoff value ≥0.6012 and corresponding retrograde pathline length ≥3 cm in 4D flow MRI. Conclusions: TEE allows predicting the length of retrograde pathlines. Hence, it may offer a cost-effective way to investigate independent predictors of DAo flow reversal in large-scale studies. However, TEE is only of limited value as a screening tool for high retrograde flow in a clinical setting, as only ∼23% of patients can be spared 4D flow MRI, which remains indispensable for the exact assessment of individual embolization pathways from plaques of the DAo in-vivo.

scholarly journals Multi-modality cerebral aneurysm haemodynamic analysis: in vivo 4D flow MRI, in vitro volumetric particle velocimetry and in silico computational fluid dynamics

2019 ◽  
Vol 16 (158) ◽  
pp. 20190465 ◽  
Author(s):  
Melissa C. Brindise ◽  
Sean Rothenberger ◽  
Benjamin Dickerhoff ◽  
Susanne Schnell ◽  
Michael Markl ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cerebral Aneurysm ◽  
Patient Specific ◽  
4D Flow Mri ◽  
4D Flow ◽  
Relative Residence Time ◽  
Flow Mri

Typical approaches to patient-specific haemodynamic studies of cerebral aneurysms use image-based computational fluid dynamics (CFD) and seek to statistically correlate parameters such as wall shear stress (WSS) and oscillatory shear index (OSI) to risk of growth and rupture. However, such studies have reported contradictory results, emphasizing the need for in-depth multi-modality haemodynamic metric evaluation. In this work, we used in vivo 4D flow MRI data to inform in vitro particle velocimetry and CFD modalities in two patient-specific cerebral aneurysm models (basilar tip and internal carotid artery). Pulsatile volumetric particle velocimetry experiments were conducted, and the particle images were processed using Shake-the-Box, a particle tracking method. Distributions of normalized WSS and relative residence time were shown to be highly yet inconsistently affected by minor flow field and spatial resolution variations across modalities, and specific relationships among these should be explored in future work. Conversely, OSI, a non-dimensional parameter, was shown to be more robust to the varying assumptions, limitations and spatial resolutions of each subject and modality. These results suggest a need for further multi-modality analysis as well as development of non-dimensional haemodynamic parameters and correlation of such metrics to aneurysm risk of growth and rupture.

scholarly journals Hemodynamic Study of a Patient-Specific Intracranial Aneurysm: Comparative Assessment of Tomographic PIV, Stereoscopic PIV, In Vivo MRI and Computational Fluid Dynamics

2021 ◽  
Author(s):  
Xiaolin Wu ◽  
Stefanie Gürzing ◽  
Christiaan Schinkel ◽  
Merel Toussaint ◽  
Romana Perinajová ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Intracranial Aneurysm ◽  
Comparative Assessment ◽  
Patient Specific ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri

Abstract Introduction Wall shear stress (WSS) is associated with the growth and rupture of an intracranial aneurysm. To reveal their underlying connections, many image-based computational fluid dynamics (CFD) studies have been conducted. However, the methodological validations using both in vivo medical imaging and in vitro optical flow measurements were rarely accompanied in such studies. Methods In the present study, we performed a comparative assessment on the hemodynamics of a patient-specific intracranial saccular aneurysm using in vivo 4D Flow MRI, in silico CFD, in vitro stereoscopic and tomographic particle imaging velocimetry (Stereo-PIV and Tomo-PIV) techniques. PIV experiments and CFD were conducted under steady state corresponding to the peak systole of 4D Flow MRI. Results The results showed that all modalities provided similar flow features and overall surface distribution of WSS. However, a large variation in the absolute WSS values was found. 4D Flow MRI estimated a 2- to 4-fold lower peak WSS (3.99 Pa) and a 1.6- to 2-fold lower mean WSS (0.94 Pa) than Tomo-PIV, Stereo-PIV, and CFD. Bland-Altman plots of WSS showed that the differences between PIV-/CFD-based WSS and 4D Flow MRI-based WSS increase with higher WSS magnitude. Such proportional trend was absent in the Bland-Altman comparison of velocity where the resolutions of PIV and CFD datasets were matched to 4D Flow MRI. We also found that because of superior resolution in the out-of-plane direction, WSS estimation by Tomo-PIV was higher than Stereo-PIV. Conclusions Our results indicated that the differences in spatial resolution could be the main contributor to the discrepancies between each modality. The findings of this study suggest that with current techniques, care should be taken when using absolute WSS values to perform a quantitative risk analysis of aneurysm rupture.

scholarly journals Four-Dimensional Flow Magnetic Resonance Imaging and Applications in Cardiology

2021 ◽  
Author(s):  
Patrick Geeraert ◽  
Hansuk Kim ◽  
Safia Ihsan Ali ◽  
Ashifa Hudani ◽  
Shirin Aliabadi ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Magnetic Resonance ◽  
Resonance Imaging ◽  
4D Flow Mri ◽  
4D Flow ◽  
Great Vessels ◽  
Flow Mri ◽  
Magnetic Resonance Imaging Mri

Blood flow through the heart and great vessels moves in three dimensions (3D) throughout time. However, the assessment of its 3D nature has been limited in the human body. Recent advances in magnetic resonance imaging (MRI) allow for the comprehensive visualization and quantification of in-vivo flow dynamics using four-dimensional (4D) flow MRI. In addition, this technique provides the opportunity to obtain advanced hemodynamic biomarkers such as vorticity, helicity, wall shear stress (WSS), pressure gradients, viscous energy loss (EL), and turbulent kinetic energy (TKE). This chapter will introduce 4D flow MRI which is currently used for blood flow visualization and advanced quantification of cardiac hemodynamic biomarkers. We will discuss its advantages relative to other in-vivo flow imaging techniques and describe its potential clinical applications in cardiology.

scholarly journals Hemodynamic study of TCPC using in vivo and in vitro 4D flow MRI and numerical simulation

2014 ◽  
Vol 16 (S1) ◽  
Author(s):  
Alejandro Roldán-Alzate ◽  
Sylvana García-Rodríguez ◽  
Leonardo Rivera ◽  
Oliver Wieben ◽  
Petros V Anagnostopoulos ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri ◽  
Hemodynamic Study

scholarly journals Associations between haemodynamics and wall enhancement of intracranial aneurysm

2021 ◽  
pp. svn-2020-000636
Author(s):  
Miaoqi Zhang ◽  
Fei Peng ◽  
Xin Tong ◽  
Xin Feng ◽  
Yunduo Li ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Resolution ◽  
Ordinal Regression ◽  
Parent Artery ◽  
Black Blood ◽  
4D Flow Mri ◽  
4D Flow ◽  
Unruptured Intracranial Aneurysms ◽  
Black Blood Mri ◽  
Flow Mri

Background and purposePrevious studies have reported about inflammation processes (IPs) that play important roles in aneurysm formation and rupture, which could be driven by blood flow. IPs can be identified using aneurysmal wall enhancement (AWE) on high-resolution black-blood MRI (BB-MRI) and blood flow haemodynamics can be demonstrated by four-dimensional-flow MRI (4D-flow MRI). Thus, this study investigated the associations between AWE and haemodynamics in unruptured intracranial aneurysms (IA) by combining 4D-flow MRI and high-resolution BB-MRI.Materials and methodsBetween April 2014 and October 2017, 48 patients with 49 unruptured IA who underwent both 4D-flow MRI and high-resolution BB-MRI were retrospectively included in this study. The haemodynamic parameters demonstrated using 4D-flow MRI were compared between different AWE patterns using the Kruskal-Wallis test and ordinal regression.ResultsThe results of Kruskal-Wallis test showed that the average wall shear stress in the IA (WSSavg-IA), maximum through-plane velocity in the adjacent parent artery, inflow jet patterns and the average vorticity in IA (vorticityavg-IA) were significantly associated with the AWE patterns. Ordinal regression analysis identified WSSavg-IA (p=0.002) and vorticityavg-IA (p=0.033) as independent predictors of AWE patterns.ConclusionA low WSS and low average vorticity were independently associated with a high AWE grade for IAs larger than 4 mm. Therefore, WSS and average vorticity could predict AWE and circumferential AWE.

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