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Phase contrast Magnetic aortic

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https://www.readbyqxmd.com/read/28714282/variability-of-4d-flow-parameters-when-subjected-to-changes-in-mri-acquisition-parameters-using-a-realistic-thoracic-aortic-phantom
#1
Cristian Montalba, Jesus Urbina, Julio Sotelo, Marcelo E Andia, Cristian Tejos, Pablo Irarrazaval, Daniel E Hurtado, Israel Valverde, Sergio Uribe
PURPOSE: To assess the variability of peak flow, mean velocity, stroke volume, and wall shear stress measurements derived from 3D cine phase contrast (4D flow) sequences under different conditions of spatial and temporal resolutions. METHODS: We performed controlled experiments using a thoracic aortic phantom. The phantom was connected to a pulsatile flow pump, which simulated nine physiological conditions. For each condition, 4D flow data were acquired with different spatial and temporal resolutions...
July 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28694784/4d-flow-analysis-of-bav-related-fluid-dynamic-alterations-evidences-of-wall-shear-stress-alterations-in-absence-of-clinically-relevant-aortic-anatomical-remodeling
#2
Filippo Piatti, Francesco Sturla, Malenka M Bissell, Selene Pirola, Massimo Lombardi, Igor Nesteruk, Alessandro Della Corte, Alberto C L Redaelli, Emiliano Votta
Bicuspid aortic valve (BAV) is the most common congenital cardiac disease and is a foremost risk factor for aortopathies. Despite the genetic basis of BAV and of the associated aortopathies, BAV-related alterations in aortic fluid-dynamics, and particularly in wall shear stresses (WSSs), likely play a role in the progression of aortopathy, and may contribute to its pathogenesis. To test whether WSS may trigger aortopathy, in this study we used 4D Flow sequences of phase-contrast cardiac magnetic resonance imaging (CMR) to quantitatively compare the in vivo fluid dynamics in the thoracic aorta of two groups of subjects: (i) five prospectively enrolled young patients with normo-functional BAV and with no aortic dilation and (ii) ten age-matched healthy volunteers...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28673664/on-the-choice-of-outlet-boundary-conditions-for-patient-specific-analysis-of-aortic-flow-using-computational-fluid-dynamics
#3
S Pirola, Z Cheng, O A Jarral, D P O'Regan, J R Pepper, T Athanasiou, X Y Xu
Boundary conditions (BCs) are an essential part in computational fluid dynamics (CFD) simulations of blood flow in large arteries. Although several studies have investigated the influence of BCs on predicted flow patterns and hemodynamic wall parameters in various arterial models, there is a lack of comprehensive assessment of outlet BCs for patient-specific analysis of aortic flow. In this study, five different sets of outlet BCs were tested and compared using a subject-specific model of a normal aorta. Phase-contrast magnetic resonance imaging (PC-MRI) was performed on the same subject and velocity profiles extracted from the in vivo measurements were used as the inlet boundary condition...
June 20, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28626199/oxygen-and-glucose-as-stimulation-agents-for-bold-functional-mr-imaging-of-rabbit-liver-a-feasibility-study
#4
Fang Yuan, Bin Song, Zixing Huang, Xijiao Liu, Chunchao Xia
PURPOSE: To assess the feasibility of using oxygen and glucose as stimulating agents in blood-oxygen-level-dependent (BOLD) Functional Magnetic Resonance Imaging (fMRI) of rabbit liver and analyze the impacts by blood flow. METHODS: Pure oxygen inhalation, intravenous injection and oral administration of glucose were given to 11 New Zealand white rabbits to compare the differences of liver T2*, aortic flow (AF), portal vein flow (PVF), aortic area (AA) and portal vein area (PVA) before and at 5 min, 10 min, 20 min, 30 min after administrations...
June 16, 2017: Magnetic Resonance in Medical Sciences: MRMS
https://www.readbyqxmd.com/read/28623496/association-between-flow-skewness-and-aortic-dilatation-in-patients-with-aortic-stenosis
#5
Hojin Ha, Hyun Jung Koo, June Goo Lee, Guk Bae Kim, Jihoon Kweon, Sang Joon Lee, Joon Won Kang, Tae Hwan Lim, Dae Hee Kim, Jong Min Song, Duk Hyun Kang, Jae Kwan Song, Young Hak Kim, Namkug Kim, Dong Hyun Yang
We investigated association between hemodynamic characteristics and aortic dilatation in patients with severe aortic stenosis (AS). Eighty patients with severe AS (mean age, 67.2 ± 12.5 years) who underwent multi-detector computed tomography and phase-contrast magnetic resonance imaging at the ascending aorta were retrospectively analyzed. Patients with an ascending aorta diameter >4 cm had a significantly higher forward flow rate at systole (28.5 ± 6.0 vs. 36.2 ± 8.6 L min, P < 0...
June 16, 2017: International Journal of Cardiovascular Imaging
https://www.readbyqxmd.com/read/28608325/pulsatile-flow-leads-to-intimal-flap-motion-and-flow-reversal-in-an-in-vitro-model-of-type-b-aortic-dissection
#6
Joav Birjiniuk, Lucas H Timmins, Mark Young, Bradley G Leshnower, John N Oshinski, David N Ku, Ravi K Veeraswamy
Understanding of the hemodynamics of Type B aortic dissection may improve outcomes by informing upon patient selection, device design, and deployment strategies. This project characterized changes to aortic hemodynamics as the result of dissection. We hypothesized that dissection would lead to elevated flow reversal and disrupted pulsatile flow patterns in the aorta that can be detected and quantified by non-invasive magnetic resonance imaging. Flexible, anatomic models of both normal aorta and dissected aorta, with a mobile intimal flap containing entry and exit tears, were perfused with a physiologic pulsatile waveform...
June 12, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28453794/blood-flow-competition-after-aortic-valve-bypass-an-evaluation-using-computational-fluid-dynamics
#7
Koji Kawahito, Naoyuki Kimura, Kenji Komiya, Masanori Nakamura, Yoshio Misawa
OBJECTIVES: Aortic valve bypass (AVB) (apico-aortic conduit) remains an effective surgical alternative for patients in whom surgical aortic valve replacement or transcatheter aortic valve implantation is not feasible. However, specific complications include thrombus formation, possibly caused by stagnation arising from flow competition between the antegrade and retrograde flow, but this has not been fully investigated. The aim of this study was to analyse flow characteristics after AVB and to elucidate mechanisms of intra-aortic thrombus using computational fluid dynamics (CFD)...
May 1, 2017: Interactive Cardiovascular and Thoracic Surgery
https://www.readbyqxmd.com/read/28421174/utility-of-cardiovascular-magnetic-resonance-derived-wave-intensity-analysis-as-a-marker-of-ventricular-function-in-children-with-heart-failure-and-normal-ejection-fraction
#8
Hopewell N Ntsinjana, Robin Chung, Paolo Ciliberti, Vivek Muthurangu, Silvia Schievano, Jan Marek, Kim H Parker, Andrew M Taylor, Giovanni Biglino
OBJECTIVE: This study sought to explore the diagnostic insight of cardiovascular magnetic resonance (CMR)-derived wave intensity analysis to better study systolic dysfunction in young patients with chronic diastolic dysfunction and preserved ejection fraction (EF), comparing it against other echocardiographic and CMR parameters. BACKGROUND: Evaluating systolic and diastolic dysfunctions in children is challenging, and a gold standard method is currently lacking...
2017: Frontiers in Pediatrics
https://www.readbyqxmd.com/read/28346330/differentiation-of-impaired-from-preserved-hemodynamics-in-patients-with-fontan-circulation-using-real-time-phase-velocity-cardiovascular-magnetic-resonance
#9
Hermann Körperich, Katja Müller, Peter Barth, Jürgen Gieseke, Nikolaus Haas, Ingram Schulze-Neick, Wolfgang Burchert, Deniz Kececioglu, Kai T Laser
PURPOSE: Progressive impairment of hemodynamics in patients with Fontan circulation is common, multifactorial, and associated with decreased quality of life and increased morbidity. We sought to assess hemodynamic differences between patients with preserved (preserved Fontans) and those with impaired circulation (impaired Fontans) after pulmonary vasodilation using oxygen and under forced breathing conditions. MATERIALS AND METHODS: Real-time phase-contrast cardiovascular magnetic resonance was performed using non-ECG triggered echo-planar imaging (temporal resolution=24 to 28 ms) in the ascending aorta (AAo) and superior vena cava (SVC)/inferior vena cava (IVC) on room air, after 100% oxygen inhalation (4 L/min; 10 min) and on forced breathing in 29 Fontan patients (17...
May 2017: Journal of Thoracic Imaging
https://www.readbyqxmd.com/read/28342532/shear-scaling-based-approach-for-irreversible-energy-loss-estimation-in-stenotic-aortic-flow-an-in-vitro-study
#10
Utku Gülan, Christian Binter, Sebastian Kozerke, Markus Holzner
Today, the functional and risk assessment of stenosed arteries is mostly based on ultrasound Doppler blood flow velocity measurements or catheter pressure measurements, which rely on several assumptions. Alternatively, blood velocity including turbulent kinetic energy (TKE) may be measured using MRI. The aim of the present study is to validate a TKE-based approach that relies on the fact that turbulence production is dominated by the flow's shear to determine the total irreversible energy loss from MRI scans...
March 12, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28317480/novel-insights-into-complex-cardiovascular-pathologies-using-4d-flow-analysis-by-cardiovascular-magnetic-resonance-imaging
#11
Adam James Lewandowski, Betty Raman, Rajarshi Banerjee, Matteo Milanesi
BACKGROUND: It is essential that we are able to assess variations in blood flow in order to fully understand cardiovascular function in disease pathologies and for identification of individuals at long-term risk of cardiovascular disease development. Qualitative and quantitative assessments of blood flow by imaging modalities have been limited, and much of the accurate quantification has relied on invasive measures. METHODS: This review discusses how four-dimensional velocity cardiovascular magnetic resonance (4D flow CMR) offers increasing potential for the non-invasive assessment of blood flow in the heart and major blood vessels such as the aorta...
March 17, 2017: Current Pharmaceutical Design
https://www.readbyqxmd.com/read/28301100/comparison-of-mr-flow-quantification-in-peripheral-and-main-pulmonary-arteries-in-patients-after-right-ventricular-outflow-tract-surgery-a-retrospective-study
#12
Tobias Rutz, Christian Meierhofer, Susanne Naumann, Stefan Martinoff, Peter Ewert, Heiko C Stern, Sohrab Fratz
PURPOSE: To compare the quantification of pulmonary stroke volume (SV) by phase contrast magnetic resonance (PC-MR) in the main pulmonary artery (MPA) to the sum of SVs in both peripheral pulmonary arteries (PPA) in different right ventricular (RV) outflow pathologies. MATERIALS AND METHODS: Pulmonary SV was determined by PC-MR in the MPA and the PPA in healthy individuals (H, n = 54), patients after correction for tetralogy of Fallot with significant pulmonary regurgitation and without pulmonary or RV outflow tract stenosis (PR, n = 50), and in patients with RV outflow tract or pulmonary valve stenosis (PS, n = 50)...
March 16, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28270219/quantification-of-aortic-stenosis-diagnostic-parameters-comparison-of-fast-3-direction-and-1-direction-phase-contrast-cmr-and-transthoracic-echocardiography
#13
Juliana Serafim da Silveira, Matthew Smyke, Adam V Rich, Yingmin Liu, Ning Jin, Debbie Scandling, Jennifer A Dickerson, Carlos E Rochitte, Subha V Raman, Lee C Potter, Rizwan Ahmad, Orlando P Simonetti
BACKGROUND: Aortic stenosis (AS) is a common valvular disorder, and disease severity is currently assessed by transthoracic echocardiography (TTE). However, TTE results can be inconsistent in some patients, thus other diagnostic modalities such as cardiovascular magnetic resonance (CMR) are demanded. While traditional unidirectional phase-contrast CMR (1Dir PC-CMR) underestimates velocity if the imaging plane is misaligned to the flow direction, multi-directional acquisitions are expected to improve velocity measurement accuracy...
March 7, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/28270208/aortic-length-measurements-for-pulse-wave-velocity-calculation-manual-2d-vs-automated-3d-centreline-extraction
#14
Arna van Engelen, Miguel Silva Vieira, Isma Rafiq, Marina Cecelja, Torben Schneider, Hubrecht de Bliek, C Alberto Figueroa, Tarique Hussain, Rene M Botnar, Jordi Alastruey
BACKGROUND: Pulse wave velocity (PWV) is a biomarker for the intrinsic stiffness of the aortic wall, and has been shown to be predictive for cardiovascular events. It can be assessed using cardiovascular magnetic resonance (CMR) from the delay between phase-contrast flow waveforms at two or more locations in the aorta, and the distance on CMR images between those locations. This study aimed to investigate the impact of different distance measurement methods on PWV. We present and evaluate an algorithm for automated centreline tracking in 3D images, and compare PWV calculations using distances derived from 3D images to those obtained from a conventional 2D oblique-sagittal image of the aorta...
March 8, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/28240794/phase-contrast-mr-flow-imaging-a-tool-to-determine-hepatic-hemodynamics-in-rats-with-a-healthy-fibrotic-or-cirrhotic-liver
#15
Denise Schaffner, Dominik von Elverfeldt, Peter Deibert, Adhara Lazaro, Irmgard Merfort, Lisa Lutz, Jakob Neubauer, Manfred W Baumstark, Wolfgang Kreisel, Wilfried Reichardt
PURPOSE: To test a magnetic resonance (MR) scanning protocol as a noninvasive tool to determine hepatic hemodynamics and to assess the degree of liver fibrosis in an animal model of liver fibrosis and cirrhosis. MATERIALS AND METHODS: Fifty-four male Wistar rats were studied. Thirty-nine received thioacetamide (TAA) in their drinking water for either 12 or 16 weeks. MR measurements were performed using flow-sensitive 2D phase-contrast MRI and a 9.4T preclinical scanner...
February 27, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28194732/late-post-avr-progression-of-bicuspid-aortopathy-link-to-hemodynamics
#16
Shiho Naito, Tatiana Gross, Kushtrim Disha, Yskert von Kodolitsch, Hermann Reichenspurner, Evaldas Girdauskas
BACKGROUND AND AIM OF THE STUDY: The ascending aortic dilatation may progress after aortic valve replacement (AVR) in bicuspid aortic valve (BAV) patients. Our aim was to evaluate rheological flow patterns and histological characteristics of the aneurysmal aorta in BAV patients at the time of reoperative aortic surgery. MATERIALS AND METHODS: 13 patients (mean age: 42 ± 9 years, 10 (77%) male) with significant progression of proximal aortopathy after isolated AVR surgery for BAV disease (i...
May 2017: General Thoracic and Cardiovascular Surgery
https://www.readbyqxmd.com/read/28190607/patient-specific-assessment-of-hemodynamics-by-computational-fluid-dynamics-in-patients-with-bicuspid-aortopathy
#17
Naoyuki Kimura, Masanori Nakamura, Kenji Komiya, Satoshi Nishi, Atsushi Yamaguchi, Osamu Tanaka, Yoshio Misawa, Hideo Adachi, Koji Kawahito
OBJECTIVE: Hemodynamics related to eccentric blood flow may factor into the development of bicuspid aortic valve aortopathy. We investigated wall shear stress distribution by means of magnetic resonance imaging-based computational fluid dynamics in patients with a bicuspid aortic valve. METHODS: Included were 12 patients with a bicuspid aortic valve (aortic stenosis, n = 11; root enlargement, n = 1). Three patients with a normal tricuspid aortic valve (arch aneurysm, n = 1; descending aortic aneurysm, n = 2) were included for comparison...
January 11, 2017: Journal of Thoracic and Cardiovascular Surgery
https://www.readbyqxmd.com/read/28125720/false-lumen-flow-patterns-and-their-relation-with-morphological-and-biomechanical-characteristics-of-chronic-aortic-dissections-computational-model-compared-with-magnetic-resonance-imaging-measurements
#18
Paula A Rudenick, Patrick Segers, Victor Pineda, Hug Cuellar, David García-Dorado, Arturo Evangelista, Bart H Bijnens
Aortic wall stiffness, tear size and location and the presence of abdominal side branches arising from the false lumen (FL) are key properties potentially involved in FL enlargement in chronic aortic dissections (ADs). We hypothesize that temporal variations on FL flow patterns, as measured in a cross-section by phase-contrast magnetic resonance imaging (PC-MRI), could be used to infer integrated information on these features. In 33 patients with chronic descending AD, instantaneous flow profiles were quantified in the FL at diaphragm level by PC-MRI...
2017: PloS One
https://www.readbyqxmd.com/read/28119407/blood-flow-competition-after-aortic-valve-bypass-an-evaluation-using-computational-fluid-dynamics
#19
Koji Kawahito, Naoyuki Kimura, Kenji Komiya, Masanori Nakamura, Yoshio Misawa
OBJECTIVES: Aortic valve bypass (AVB) (apico-aortic conduit) remains an effective surgical alternative for patients in whom surgical aortic valve replacement or transcatheter aortic valve implantation is not feasible. However, specific complications include thrombus formation, possibly caused by stagnation arising from flow competition between the antegrade and retrograde flow, but this has not been fully investigated. The aim of this study was to analyse flow characteristics after AVB and to elucidate mechanisms of intra-aortic thrombus using computational fluid dynamics (CFD)...
January 24, 2017: Interactive Cardiovascular and Thoracic Surgery
https://www.readbyqxmd.com/read/28115510/abnormal-wave-reflections-and-left-ventricular-hypertrophy-late-after-coarctation-of-the-aorta-repair
#20
Michael A Quail, Rebekah Short, Bejal Pandya, Jennifer A Steeden, Abbas Khushnood, Andrew M Taylor, Patrick Segers, Vivek Muthurangu
Patients with repaired coarctation of the aorta are thought to have increased afterload due to abnormalities in vessel structure and function. We have developed a novel cardiovascular magnetic resonance protocol that allows assessment of central hemodynamics, including central aortic systolic blood pressure, resistance, total arterial compliance, pulse wave velocity, and wave reflections. The main study aims were to (1) characterize group differences in central aortic systolic blood pressure and peripheral systolic blood pressure, (2) comprehensively evaluate afterload (including wave reflections) in the 2 groups, and (3) identify possible biomarkers among covariates associated with elevated left ventricular mass (LVM)...
March 2017: Hypertension
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