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

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.

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

Scientific Reports ◽

10.1038/s41598-021-89636-z ◽

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.

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

Journal of Magnetic Resonance Imaging ◽

10.1002/jmri.24233 ◽

2013 ◽

Vol 39 (4) ◽

pp. 819-826 ◽

Cited By ~ 12

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

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Pseudo‐spiral sampling and compressed sensing reconstruction provides flexibility of temporal resolution in accelerated aortic 4D flow MRI: A comparison with k‐t principal component analysis

NMR in Biomedicine ◽

10.1002/nbm.4255 ◽

2020 ◽

Vol 33 (4) ◽

Author(s):

Lukas M. Gottwald ◽

Eva S. Peper ◽

Qinwei Zhang ◽

Bram F. Coolen ◽

Gustav J. Strijkers ◽

...

Keyword(s):

Principal Component Analysis ◽

Compressed Sensing ◽

Temporal Resolution ◽

Principal Component ◽

Component Analysis ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri

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Reduced regional flow in the left ventricle after anterior acute myocardial infarction: a case control study using 4D flow MRI

BMC Medical Imaging ◽

10.1186/s12880-019-0404-7 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

Philip A. Corrado ◽

Jacob A. Macdonald ◽

Christopher J. François ◽

Niti R. Aggarwal ◽

Jonathan W. Weinsaft ◽

...

Keyword(s):

Myocardial Infarction ◽

Acute Myocardial Infarction ◽

Linear Models ◽

Left Ventricular ◽

Short Axis ◽

Flow Data ◽

4D Flow Mri ◽

4D Flow ◽

Regional Flow ◽

Flow Mri

Abstract Background Acute myocardial infarction (AMI) alters left ventricular (LV) hemodynamics, resulting in decreased global LV ejection fraction and global LV kinetic energy. We hypothesize that anterior AMI effects localized alterations in LV flow and developed a regional approach to analyze these local changes with 4D flow MRI. Methods 4D flow cardiac magnetic resonance (CMR) data was compared between 12 anterior AMI patients (11 males; 66 ± 12yo; prospectively acquired in 2016–2017) and 19 healthy volunteers (10 males; 40 ± 16yo; retrospective from 2010 to 2011 study). The LV cavity was contoured on short axis cine steady-state free procession CMR and partitioned into three regions: base, mid-ventricle, and apex. 4D flow data was registered to the short axis segmentation. Peak systolic and diastolic through-plane flows were compared region-by-region between groups using linear models of flow with age, sex, and heart rate as covariates. Results Peak systolic flow was reduced in anterior AMI subjects compared to controls in the LV mid-ventricle (fitted reduction = 3.9 L/min; P = 0.01) and apex (fitted reduction = 1.4 L/min; P = 0.02). Peak diastolic flow was also lower in anterior AMI subjects compared to controls in the apex (fitted reduction = 2.4 L/min; P = 0.01). Conclusions A regional method to analyze 4D LV flow data was applied in anterior AMI patients and controls. Anterior AMI patients had reduced regional flow relative to controls.

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Scan–rescan reproducibility of diastolic left ventricular kinetic energy, viscous energy loss and vorticity assessment using 4D flow MRI: analysis in healthy subjects

The International Journal of Cardiovascular Imaging ◽

10.1007/s10554-017-1291-z ◽

2018 ◽

Vol 34 (6) ◽

pp. 905-920 ◽

Cited By ~ 6

Author(s):

Vivian P. Kamphuis ◽

Jos J. M. Westenberg ◽

Roel L. F. van der Palen ◽

Pieter J. van den Boogaard ◽

Rob J. van der Geest ◽

...

Keyword(s):

Kinetic Energy ◽

Energy Loss ◽

Healthy Subjects ◽

Left Ventricular ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri

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Unilateral branch pulmonary artery stenting in tetralogy of fallot improves ventricular function

European Heart Journal - Cardiovascular Imaging ◽

10.1093/ehjci/jeab090.066 ◽

2021 ◽

Vol 22 (Supplement_2) ◽

Author(s):

MM Bissell ◽

L Mills ◽

DGW Cave ◽

R Foley ◽

JP Greenwood ◽

...

Keyword(s):

Kinetic Energy ◽

Ejection Fraction ◽

Pulmonary Artery ◽

Longitudinal Strain ◽

Left Ventricular ◽

Energy Curve ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NIHR Background Pulmonary artery stenosis (PAS) occurs commonly in patients with tetralogy of fallot (ToF). Cardiac function and especially left ventricular longitudinal strain has been identified as an important prognostic factor for long term survival in ToF. The clinical relevance of unilateral PAS to long-term bi-ventricular function is poorly understood. Purpose We sought to evaluate the effect of resolving unilateral pulmonary artery obstruction on right and left ventricular performance. Methods We prospectively included 40 patients with TOF between 2016 and 2020, 20 who underwent unilateral PAS stenting and as comparison 20 who underwent surgical pulmonary valve replacement (PVR). MRI data was acquired during routine clinical care before and around 6-12 months after the procedure. 4 PAS patients attended additional research scans acquiring ventricular 4D flow MRI data. 4D flow MRI data was compared to the average kinetic energy curve of 10 age-matched healthy volunteers. Results Of the 20 patients undergoing PAS, 2 also underwent percutaneous PVR and were excluded from the comparison analysis. All patients in the PAs group showed an improvement in branch PA flow differential post procedure. Patients undergoing PAS were younger than those undergoing PVR (median 12 vs 19 years, p < 0.001). Other baseline anatomical and functional parameters including right ventricular (RV) volume indexed to body surface are (RVEDV/BSA) were comparable (pre PAS median 151 [122,170] vs pre PVR 162 [140,191]; p = 0.217). While in the PVR group the right ventricular volumes reduced in both end-diastole and end-systole, in the PAS group RV function improved due to reduced end-systolic volume with largely stable end-diastolic volumes. Changes in the left ventricle (LV) were even more interesting. In the PVR group ejection fraction improved due to an increase in end-diastolic volume with no improvement in ventricular longitudinal strain. In contrast, in the PAS group LV ejection fraction improved by a reduction in end-systolic volume and the PAS group showed a small but significant improvement in LV longitudinal strain. In addition, ¾ patients undergoing 4D flow MRI assessment showed LV kinetic energy curve more similar to the healthy volunteer averaged LV kinetic energy curve after PAS. The 4th patient already had a near normal LV kinetic energy curve prior to PAS. Conclusion Unilateral PAS does not alter RV end-diastolic volumes but improves RV function. LV ejection fraction improvement is similar to that seen after PVR, but importantly PAS also improved LV longitudinal strain. This suggests that PAS might positively influence long term morbidity and mortality risk in ToF patients, but a larger multi-centre long term follow-up study is needed to confirm this.

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Assessment of left ventricular diastolic flow in hypertrophic cardiomyopathy by 4D FLOW MRI

Medical Visualization ◽

10.24835/1607-0763-2019-4-42-49 ◽

2019 ◽

pp. 42-49

Author(s):

E. Yu. Glazkova ◽

O. Yu. Dariy ◽

S. A. Aleksandrova ◽

V. N. Makarenko ◽

M. I. Berseneva ◽

...

Keyword(s):

Blood Flow ◽

Hypertrophic Cardiomyopathy ◽

Phase Contrast ◽

Peak Velocity ◽

Left Ventricular ◽

Vortical Flow ◽

4D Flow ◽

Phase Contrast Mri ◽

Flow Phase ◽

Flow Mri

Objective. To assess phase-contrast MRI in the evaluation of left ventricular hemodynamics changes in various forms of hypertrophic cardiomyopathy.Materials and methods. 11 patients were examined: without pathology of the cardiovascular system (n = 3), with apical (n = 3), diffuse-septal (n = 2) and focal-basal (n = 3) types of hypertrophic cardiomyopathy. All patients underwent MRI of the heart with an additional phase-contrast sequence of the left ventricular area. Postprocessing carried out in the 4D FLOW application (Siemens).Results. Data were obtained on the geometry and dynamics of vortex diastolic flows in the left ventricular of all patients. In patients with hypertrophic cardiomyopathy, an increase in the distance to the center of the vortex and a decrease in the normalized area and peak velocity of the vortex is determined. The diffuse-septal type is characterized by a minimal vortex peak velocity; apical type - by the maximum vortex sphericity index. For patients with a focalbasal type of hypertrophic cardiomyopathy the maximum changes in blood flow are determined in late diastole (absence of vortexes).Conclusion. 4D FLOW Phase-contrast MRI allows identifying and assessing LV vortical flow. Quantitative analysis can be used to characterize the remodeling of LV blood flow of various types of hypertrophic cardiomyopathy.

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

Journal of Magnetic Resonance Imaging ◽

10.1002/jmri.24703 ◽

2014 ◽

Vol 39 (4) ◽

pp. spcone-spcone ◽

Cited By ~ 1

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

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Abstract 14689: Regional Aortic Wall Shear Stress Mapping Implicates Hemodynamics in Human Bicuspid Aortopathy

Circulation ◽

10.1161/circ.130.suppl_2.14689 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

David G Guzzardi ◽

Pim van Ooij ◽

Alex J Barker ◽

Giampaolo Martufi ◽

Katherine E Olsen ◽

...

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Aortic Wall ◽

Transforming Growth Factor ◽

Patient Specific ◽

4D Flow Mri ◽

4D Flow ◽

Hemodynamic Assessment ◽

Flow Mri ◽

Wall Shear

Introduction: A suspected genetic cause for bicuspid aortic valve (BAV) aortopathy has led to aggressive resection strategies. Using 4D flow MRI, we documented increased regional wall shear stress (WSS) in BAV patients. Local hemodynamics may exacerbate extracellular matrix (ECM) degradation leading to disease progression. If validated, preoperative regional hemodynamic assessment could be used to guide more targeted patient-specific aortic resection. For the first time, we correlated regional WSS with aortic tissue remodeling in BAV patients. Methods & Results: BAV patients (N=11) undergoing ascending aortic resection received preoperative 4D flow MRI with regional WSS differences mapped. Paired aortic wall samples (from same-patient with elevated WSS paired to normal WSS regions) were collected during surgery and compared using histology (pentachrome), biomechanics (biaxial mechanical testing), and ECM regulation (protein expression). Patient mean age: 49±18 years; mean aortic diameter: 4.6±0.7cm (range: 3.6 - 6.3cm); 55% had R+L fusion pattern; 36% had severe aortic stenosis. All patients had heterogeneous WSS patterns with regions of elevated WSS adjacent to those of normal WSS. By histology, regions of increased WSS showed greater medial elastin fragmentation, fibrosis, and cystic medial necrosis compared to adjacent areas of normal WSS. Regions of increased WSS showed increased elastic modulus (fold change±SD: 1.53±0.68; P=0.06, N=5) and collagen stiffness (1.37±0.49; P=0.07, N=5) compared to normal WSS regions suggesting altered distensibility. Multiplex protein analyses of ECM regulatory molecules revealed an increase in transforming growth factor β-1 (1.49±0.71, P=0.02), MMP-1 (1.62±0.84; P=0.01), MMP-2 (1.49±1.00; P=0.06), MMP-3 (1.23±0.36; P=0.02), MMP-7 (1.57±0.75; P=0.02), and TIMP-2 (1.26±0.33; P=0.01) in elevated WSS regions suggesting ECM dysregulation consistent with aortic remodeling. Conclusions: In BAV aorta, regional WSS corresponds with local histologic abnormalities, altered biomechanics, and ECM dysregulation. These novel data strongly implicate local hemodynamics as a mediator of BAV aortopathy. With further validation, 4D flow MRI could be used to guide personalized resection strategies.

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