Segmentation of the Aorta and Pulmonary Arteries Based on 4D Flow MRI in the Pediatric Setting Using Fully Automated Multi‐Site, Multi‐Vendor, and Multi‐Label Dense U‐Net

Introduction: Cor Pulmonale or right ventricular (RV) dysfunction due to pulmonary disease is an expected complication of COPD resulting from increased afterload mediated by hypoxic pulmonary vasoconstriction as well as the destruction of the pulmonary vascular bed. Early detection of elevated RV afterload has been previously demonstrated by visualization of abnormal flow patterns in the proximal pulmonary arteries. Prior quantitative analysis of helicity in the pulmonary arteries of pulmonary hypertension patients has demonstrated a strong association between helicity and increased RV afterload. Hypothesis: Patients with COPD will have abnormal pulmonary flow as evaluated by 4D-Flow MRI and associated with RV function and pulmonary arterial stiffness. Methods: Patients with COPD (n=15) (65yrs ± 6) and controls (n=10) (58yrs ± 9) underwent 4D-Flow MRI to calculate helicity (Figure 1A). The helicity was calculated in 2 segments: 1) the main pulmonary artery (MPA) and 2) along the RV outflow tract (RVOT) - MPA axis. Main pulmonary arterial stiffness was measured using the relative area change (RAC). Results: COPD patients had decreased helicity relative to healthy controls in the MPA (19.4±7.8 vs 32.8±15.9 s -2 , P=0.007) (Figure 1B). Additionally, COPD patients had reduced helicity along the RVOT-MPA axis (33.2±9.0 vs 43.5±8.3 s -2 , P=0.010). The helicity measured in the MPA was associated with RV end-systolic volume (R=0.59, P = 0.002), RVEF (R=0.631, P<0.001), RAC (R=-0.61, P=0.001). e combined helicity along the MPA-RVOT axis was associated with RVEF (R=0.74, P<0.001), RVESV (R=-0.57, P=0.004), and RAC (R=0.42, P=0.005). Conclusion: Patients with COPD show quantitatively abnormal flow hemodynamics, when compared with healthy controls, as assessed by 4D-Flow MRI. A strong association between helicity along the MPA-RV outflow tract axis and RV function suggests that 4D-Flow MRI might be a sensitive tool in evaluating RV - pulmonary arterial coupling in COPD.

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Pulmonary Arteriovenous Pressure Gradient and Time-Averaged Mean Velocity of Small Pulmonary Arteries Can Serve as Sensitive Biomarkers in the Diagnosis of Pulmonary Arterial Hypertension: A Preclinical Study by 4D-Flow MRI

Diagnostics ◽

10.3390/diagnostics12010058 ◽

2021 ◽

Vol 12 (1) ◽

pp. 58

Author(s):

Ali Nahardani ◽

Simon Leistikow ◽

Katja Grün ◽

Martin Krämer ◽

Karl-Heinz Herrmann ◽

...

Keyword(s):

Pulmonary Arterial Hypertension ◽

Arterial Hypertension ◽

Pressure Gradient ◽

Pulmonary Arteries ◽

Preclinical Study ◽

4D Flow Mri ◽

4D Flow ◽

Mean Velocity ◽

Flow Mri ◽

Pulmonary Arterial

(1) Background: Pulmonary arterial hypertension (PAH) is a serious condition that is associated with many cardiopulmonary diseases. Invasive right heart catheterization (RHC) is currently the only method for the definitive diagnosis and follow-up of PAH. In this study, we sought a non-invasive hemodynamic biomarker for the diagnosis of PAH. (2) Methods: We applied prospectively respiratory and cardiac gated 4D-flow MRI at a 9.4T preclinical scanner on three different groups of Sprague Dawley rats: baseline (n = 11), moderate PAH (n = 8), and severe PAH (n = 8). The pressure gradients as well as the velocity values were analyzed from 4D-flow data and correlated with lung histology. (3) Results: The pressure gradient between the pulmonary artery and vein on the unilateral side as well as the time-averaged mean velocity values of the small pulmonary arteries were capable of distinguishing not only between baseline and severe PAH, but also between the moderate and severe stages of the disease. (4) Conclusions: The current preclinical study suggests the pulmonary arteriovenous pressure gradient and the time-averaged mean velocity as potential biomarkers to diagnose PAH.

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Comparison of 4D Flow MRI to 2D Flow MRI in the pulmonary arteries in healthy volunteers and patients with pulmonary hypertension

PLoS ONE ◽

10.1371/journal.pone.0224121 ◽

2019 ◽

Vol 14 (10) ◽

pp. e0224121 ◽

Cited By ~ 4

Author(s):

Malte Maria Sieren ◽

Clara Berlin ◽

Thekla Helene Oechtering ◽

Peter Hunold ◽

Daniel Drömann ◽

...

Keyword(s):

Pulmonary Hypertension ◽

Healthy Volunteers ◽

Pulmonary Arteries ◽

4D Flow Mri ◽

4D Flow ◽

2D Flow ◽

Flow Mri

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Abstract 16422: 4D Flow MRI Improves Assessment of Aortic and Pulmonary Peak Velocities in Patients With D-Transposition of Great Arteries Following Arterial Switch Operation

Circulation ◽

10.1161/circ.130.suppl_2.16422 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Kelly Jarvis ◽

Susanne Schnell ◽

Alex Barker ◽

Marleen Vonder ◽

Michael Rose ◽

...

Keyword(s):

Peak Velocity ◽

Arterial Switch Operation ◽

Pulmonary Arteries ◽

Velocity Measurements ◽

4D Flow Mri ◽

4D Flow ◽

Arterial Switch ◽

Switch Operation ◽

Significant Difference ◽

Flow Mri

BACKGROUND: Pulmonary artery stenosis is the most common complication seen following the arterial switch operation (ASO) for D-transposition of the great arteries (DTGA). During follow-up, it is important to accurately detect peak velocity as an indicator of vessel narrowing. The purpose of this study was to compare peak velocity measurements by 4D flow MRI (4D flow) (with full volumetric coverage of aorta and pulmonary system) to those by standard 2D phase contrast MRI (2D PC) and Doppler echo. METHODS: 4D flow and 2D PC were performed in n=14 subjects (age = 12.4 ± 7.6, range = 1 to 25) with DTGA s/p ASO. 3D segmentation of the aorta (Ao) and pulmonary arteries (PAs) was performed to isolate 4D flow velocities for these vessels (Figure a). The location and value of peak systolic velocity was determined inside volumes of interest for the ascending aorta (AAO), main (MPA), right (RPA) and left pulmonary arteries (LPA). RPA and LPA 2D PC data were not available in one patient. Contemporary echo data were available in 11 patients (11 AAO, 8 MPA, 6 RPA, 5 LPA). RESULTS: Peak velocity measurements by 4D flow were significantly higher than 2D PC in all regions (AAO: 1.51±0.61m/s vs. 1.15±0.24m/s, p = 0.016; MPA: 2.08±1.11m/s vs. 1.44± 0.61m/s, p = 0.004; RPA: 2.19±0.65m/s vs. 1.79±0.81m/s, p = 0.027; LPA: 2.08±0.85m/s vs. 1.74±0.70m/s, p = 0.014). Regression results indicated strong relationships between 4D flow and 2D PC (AAO: R2 = 0.46, p = 0.008; MPA: R2 = 0.69, p = 0.0002; RPA: R2 =0.50, p = 0.007; LPA: R2 = 0.74, p = 0.0001) (Figure b). No significant difference was found between peak velocities measured by 4D flow and echo (AAO: p = 0.32, MPA: p = 0.24, RPA: p = 0.91, LPA: p = 0.36) or by 2D PC and echo (AAO: p = 0.49, MPA: p = 0.62, RPA: p = 0.35, LPA: p = 0.066). CONCLUSION: 4D flow outperformed 2D PC for detecting peak velocity in the Ao and PAs. No significant difference was found between peak velocities measured by 4D flow and echo. Further studies are warranted in a larger patient cohort to determine clinical impact.

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Diagnostic accuracy of 4D flow MRI comparing 2mm3 and 3mm3 spatial resolution

European Heart Journal - Cardiovascular Imaging ◽

10.1093/ehjci/jeaa356.284 ◽

2021 ◽

Vol 22 (Supplement_1) ◽

Author(s):

DGW Cave ◽

D Shelley ◽

H Michael ◽

P Garg ◽

JP Greenwood ◽

...

Keyword(s):

Kinetic Energy ◽

Spatial Resolution ◽

Pulmonary Arteries ◽

Public Institution ◽

4D Flow Mri ◽

4D Flow ◽

Funding Sources ◽

4D Flow Cmr ◽

Flow Mri ◽

Good Agreement

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): National Institute for Health Research, UK University of Leeds Background Cardiac magnetic resonance (CMR) examinations requiring repeated breath-holds are challenging in younger patients. While 4-dimensional phase-contrast (4D flow) CMR does not require breath-holds, acquisition has been lengthy. Therefore to date spatial resolution has been influenced mainly by scan length. With accelerated sequences becoming available, higher spatial resolution is becoming clinically feasible. Purpose We therefore evaluated the minimum spatial resolution in 4D flow CMR necessary for accurate clinical assessment. Methods Ten healthy volunteers (mean age 24.8 years) underwent cardiac examinations on a 3T scanner using a 4D Flow prototype sequence at 2x2x2mm3 (4DFlow2) and 3x3x3mm3 (4DFlow3) spatial resolution. Net forward flow (FF) and peak velocity (PV) using valve tracking were calculated with commercially available software and kinetic energy (KE) in the left ventricle (LV) was analysed using a research tool. Bland-Altman analysis was used for statistical assessment and is reported as bias ± limits of agreement. Results Aortic valve flow metrics were similar in 4DFlow2 (FF 94ml; PV 133cm/s) and 4DFlow3 (FF 95ml; PV 130cm/s), and both showed good agreement with 2D PC MRI (FF 93ml, Bland-Altman:1.6 ± 9.7 and 2.2 ± 13.5, respectively). Similar results were obtained for pulmonary valve flow (FF 138cm/s; Bland-Altman:4.7 ± 15.1 and 8.1 ± 18.2, respectively). Branch pulmonary artery (PA) FF showed good agreement with the main PA FF in 2D and 4DFlow2 (Bland-Altman:1.1 ± 15.9 and 1.1 ± 10.6, respectively), but not in 4DFlow3 (Bland-Altman:1.1 ± 32.5). Global LV KE measured by 4DFlow3 was on average 12% lower compared to 4DFlow2, whereas maximum systolic LV KE was similar in both acquisition methods. Conclusions 3mm3 spatial resolution appears to be sufficient for clinical evaluation of aortic and pulmonary valves. Smaller vessels such as branch pulmonary arteries require higher resolution for accurate assessment. While no gold standard is available for kinetic energy assessment, our results suggest that some parameters LV energetic assessment is spatial resolution sensitive. Differences in SNR might also contribute to the differing results. Abstract Figure. Bland-Altman plots for 4D flow MRI

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4D-Flow MRI: Beyond the Images

Seminars in Thoracic and Cardiovascular Surgery ◽

10.1053/j.semtcvs.2019.09.008 ◽

2020 ◽

Vol 32 (1) ◽

pp. 35

Author(s):

Pietro Sergio ◽

Antonio Miceli

Keyword(s):

4D Flow Mri ◽

4D Flow ◽

Flow Mri

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4D- Flow- MRI After Aortic Valve Surgery

Case Medical Research ◽

10.31525/ct1-nct04223713 ◽

2020 ◽

Author(s):

Keyword(s):

Aortic Valve ◽

Valve Surgery ◽

Aortic Valve Surgery ◽

4D Flow Mri ◽

4D Flow ◽

Flow Mri

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

Scientific Reports ◽

10.1038/s41598-021-91125-2 ◽

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.

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Associations between haemodynamics and wall enhancement of intracranial aneurysm

Stroke and Vascular Neurology ◽

10.1136/svn-2020-000636 ◽

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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