scholarly journals Assessment of Reynolds stress components and turbulent pressure loss using 4D flow MRI with extended motion encoding

2017 ◽  
Vol 79 (4) ◽  
pp. 1962-1971 ◽  
Author(s):  
Henrik Haraldsson ◽  
Sarah Kefayati ◽  
Sinyeob Ahn ◽  
Petter Dyverfeldt ◽  
Jonas Lantz ◽  
...  
Keyword(s):  
Reynolds Stress ◽  
Pressure Loss ◽  
4D Flow Mri ◽  
4D Flow ◽  
Stress Components ◽  
Turbulent Pressure ◽  
Flow Mri

scholarly journals 4D Flow MRI-based pressure loss estimation in stenotic flows: Evaluation using numerical simulations

2015 ◽  
Vol 75 (4) ◽  
pp. 1808-1821 ◽  
Author(s):  
Belen Casas ◽  
Jonas Lantz ◽  
Petter Dyverfeldt ◽  
Tino Ebbers
Keyword(s):  
Numerical Simulations ◽  
Pressure Loss ◽  
Loss Estimation ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri

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.

4D-Flow MRI: Beyond the Images

2020 ◽  
Vol 32 (1) ◽  
pp. 35
Author(s):  
Pietro Sergio ◽  
Antonio Miceli
Keyword(s):  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri

scholarly journals Circulation derived from 4D flow MRI correlates with right ventricular dysfunction in patients with tetralogy of Fallot

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nanae Tsuchiya ◽  
Michinobu Nagao ◽  
Yumi Shiina ◽  
Shohei Miyazaki ◽  
Kei Inai ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Tetralogy Of Fallot ◽  
Main Pulmonary Artery ◽  
Vortex Formation ◽  
Cine Mri ◽  
Short Axis ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri ◽  
Rv Function

AbstractWe used 4D-flow MRI to investigate circulation, an area integral of vorticity, in the main pulmonary artery (MPA) as a new hemodynamic parameter for assessing patients with a repaired Tetralogy of Fallot (TOF). We evaluated the relationship between circulation, right ventricular (RV) function and the pulmonary regurgitant fraction (PRF). Twenty patients with a repaired TOF underwent cardiac MRI. Flow-sensitive 3D-gradient sequences were used to obtain 4D-flow images. Vortex formation in the MPA was visualized, with short-axis and longitudinal vorticities calculated by software specialized for 4D flow. The RV indexed end-diastolic/end-systolic volumes (RVEDVi/RVESVi) and RV ejection fraction (RVEF) were measured by cine MRI. The PR fraction (PRF) and MPA area were measured by 2D phase-contrast MRI. Spearman ρ values were determined to assess the relationships between circulation, RV function, and PRF. Vortex formation in the MPA occurred in 15 of 20 patients (75%). The longitudinal circulation (11.7 ± 5.1 m2/s) was correlated with the RVEF (ρ = − 0.85, p = 0.0002), RVEDVi (ρ = 0.62, p = 0.03), and RVESVi (ρ = 0.76, p = 0.003) after adjusting for the MPA size. The short-axis circulation (9.4 ± 3.4 m2/s) in the proximal MPA was positively correlated with the MPA area (ρ = 0.61, p = 0.004). The relationships between the PRF and circulation or RV function were not significant. Increased longitudinal circulation in the MPA, as demonstrated by circulation analysis using 4D flow MRI, was related to RV dysfunction in patients with a repaired TOF.

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.

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 Four-Dimensional Flow MRI of Abdominal Veins: A Systematic Review

Diagnostics ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 767
Author(s):  
Simon O. Haarbye ◽  
Michael B. Nielsen ◽  
Adam E. Hansen ◽  
Carsten A. Lauridsen
Keyword(s):  
Systematic Review ◽  
Blood Flow ◽  
Portal Hypertension ◽  
Healthy Subjects ◽  
Visual Quality ◽  
Sampling Strategies ◽  
4D Flow Mri ◽  
4D Flow ◽  
Dimensional Flow ◽  
Flow Mri

The aim of this systematic review is to provide an overview of the use of Four-Dimensional Magnetic Resonance Imaging of vector blood flow (4D Flow MRI) in the abdominal veins. This study was composed according to the PRISMA guidelines 2009. The literature search was conducted in MEDLINE, Cochrane Library, EMBASE, and Web of Science. Quality assessment of the included studies was performed using the QUADAS-2 tool. The initial search yielded 781 studies and 21 studies were included. All studies successfully applied 4D Flow MRI in abdominal veins. Four-Dimensional Flow MRI was capable of discerning between healthy subjects and patients with cirrhosis and/or portal hypertension. The visual quality and inter-observer agreement of 4D Flow MRI were rated as excellent and good to excellent, respectively, and the studies utilized several different MRI data sampling strategies. By applying spiral sampling with compressed sensing to 4D Flow MRI, the blood flow of several abdominal veins could be imaged simultaneously in 18–25 s, without a significant loss of visual quality. Four-Dimensional Flow MRI might be a useful alternative to Doppler sonography for the diagnosis of cirrhosis and portal hypertension. Further clinical studies need to establish consensus regarding MRI sampling strategies in patients and healthy subjects.

scholarly journals Enhancement of cerebrovascular 4D flow MRI velocity fields using machine learning and computational fluid dynamics simulation data

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
David R. Rutkowski ◽  
Alejandro Roldán-Alzate ◽  
Kevin M. Johnson
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Velocity Fields ◽  
Dynamics Simulation ◽  
Patient Specific ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Phase ◽  
Flow Mri ◽  
Trained Network

AbstractBlood flow metrics obtained with four-dimensional (4D) flow phase contrast (PC) magnetic resonance imaging (MRI) can be of great value in clinical and experimental cerebrovascular analysis. However, limitations in both quantitative and qualitative analyses can result from errors inherent to PC MRI. One method that excels in creating low-error, physics-based, velocity fields is computational fluid dynamics (CFD). Augmentation of cerebral 4D flow MRI data with CFD-informed neural networks may provide a method to produce highly accurate physiological flow fields. In this preliminary study, the potential utility of such a method was demonstrated by using high resolution patient-specific CFD data to train a convolutional neural network, and then using the trained network to enhance MRI-derived velocity fields in cerebral blood vessel data sets. Through testing on simulated images, phantom data, and cerebrovascular 4D flow data from 20 patients, the trained network successfully de-noised flow images, decreased velocity error, and enhanced near-vessel-wall velocity quantification and visualization. Such image enhancement can improve experimental and clinical qualitative and quantitative cerebrovascular PC MRI analysis.

scholarly journals B-PO04-077 HEART RATE VARIABILITY AND LEFT ATRIAL HEMODYNAMICS IN ATRIAL FIBRILLATION MEASURED WITH 4D FLOW MRI

Heart Rhythm ◽  
2021 ◽  
Vol 18 (8) ◽  
pp. S310
Author(s):  
Amanda DiCarlo ◽  
Justin Baraboo ◽  
Mitchell A. Collins ◽  
Maurice Pradella ◽  
Patrick M. McCarthy ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Left Atrial ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri
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