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Phase contrast Magnetic aortic

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https://www.readbyqxmd.com/read/28453794/blood-flow-competition-after-aortic-valve-bypass-an-evaluation-using-computational-fluid-dynamics
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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
https://www.readbyqxmd.com/read/28088917/effects-of-heart-valve-prostheses-on-phase-contrast-flow-measurements-in-cardiovascular-magnetic-resonance-a-phantom-study
#15
Johanna Richau, Matthias A Dieringer, Julius Traber, Florian von Knobelsdorff-Brenkenhoff, Andreas Greiser, Carsten Schwenke, Jeanette Schulz-Menger
BACKGROUND: Cardiovascular Magnetic Resonance is often used to evaluate patients after heart valve replacement. This study systematically analyses the influence of heart valve prostheses on phase contrast measurements in a phantom trial. METHODS: Two biological and one mechanical aortic valve prostheses were integrated in a flow phantom. B0 maps and phase contrast measurements were acquired at a 1.5 T MR scanner using conventional gradient-echo sequences in predefined distances to the prostheses...
January 16, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/28063459/cardiac-remodeling-following-reperfused-acute-myocardial-infarction-is-linked-to-the-concomitant-evolution-of-vascular-function-as-assessed-by-cardiovascular-magnetic-resonance
#16
Olivier Huttin, Damien Mandry, Romain Eschalier, Lin Zhang, Emilien Micard, Freddy Odille, Marine Beaumont, Renaud Fay, Jacques Felblinger, Edoardo Camenzind, Faïez Zannad, Nicolas Girerd, Pierre Y Marie
BACKGROUND: Left ventricular (LV) remodeling following acute myocardial infarction (MI) is difficult to predict at an individual level although a possible interfering role of vascular function has yet to be considered to date. This study aimed to determine the extent to which this LV remodeling is influenced by the concomitant evolution of vascular function and LV loading conditions, as assessed by phase-contrast Cardiovascular Magnetic Resonance (CMR) of the ascending aorta. METHODS: CMR was performed in 121 patients, 2-4 days after reperfusion of a first ST-segment elevation myocardial infarction and 6 months thereafter...
January 4, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/27989036/ascending-aortic-stiffness-with-bicuspid-aortic-valve-is-variable-and-not-predicted-by-conventional-parameters-in-young-patients
#17
Nicholas S Burris, Petter Dyverfeldt, Michael D Hope
BACKGROUND: Bicuspid aortic valve (BAV)-related aortopathy is characterized by histological abnormalities that result in aortic wall stiffening and aortic dilation. The study aim was to determine the range of ascending aortic stiffness seen in a clinical cohort of patients with BAV, and to identify the association of aortic stiffness with standard clinical and imaging parameters. METHODS: Patients with BAV (n = 65) and normal subjects (n = 10) were studied using conventional phase-contrast magnetic resonance imaging through the ascending aorta...
May 2016: Journal of Heart Valve Disease
https://www.readbyqxmd.com/read/27942477/the-effect-of-reducing-spatial-resolution-by-in-plane-partial-volume-averaging-on-peak-velocity-measurements-in-phase-contrast-magnetic-resonance-angiography
#18
Jonathan Rodrigues, Kishore Minhas, Guido Pieles, Elisa McAlindon, Christopher Occleshaw, Nathan Manghat, Mark Hamilton
BACKGROUND: The aim of this study was to quantify the degree of the effect of in-plane partial volume averaging on recorded peak velocity in phase contrast magnetic resonance angiography (PCMRA). METHODS: Using cardiac optimized 1.5 Tesla MRI scanners (Siemens Symphony and Avanto), 145 flow measurements (14 anatomical locations; ventricular outlets, aortic valve (AorV), aorta (5 sites), pulmonary arteries (3 sites), pulmonary veins, superior and inferior vena cava)- in 37 subjects (consisting of healthy volunteers, congenital and acquired heart disease patients) were analyzed by Siemens Argus default voxel averaging technique (where peak velocity = mean of highest velocity voxel and four neighbouring voxels) and by single voxel technique (1...
October 2016: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/27847162/patient-specific-computational-fluid-dynamics-assessment-of-aortic-hemodynamics-in-a-spectrum-of-aortic-valve-pathologies
#19
Pouya Youssefi, Alberto Gomez, Taigang He, Lisa Anderson, Nick Bunce, Rajan Sharma, C Alberto Figueroa, Marjan Jahangiri
OBJECTIVES: The complexity of aortic disease is not fully exposed by aortic dimensions alone, and morbidity or mortality can occur before intervention thresholds are met. Patient-specific computational fluid dynamics (CFD) were used to assess the effect of different aortic valve morphologies on velocity profiles, flow patterns, helicity, wall shear stress (WSS), and oscillatory shear index (OSI) in the thoracic aorta. METHODS: A total of 45 subjects were divided into 5 groups: volunteers, aortic regurgitation-tricuspid aortic valve (AR-TAV), aortic stenosis-tricuspid aortic valve (AS-TAV), aortic stenosis-bicuspid aortic valve right-left cusp fusion (BAV[RL]), and aortic stenosis-right-non cusp fusion (AS-BAV[RN])...
January 2017: Journal of Thoracic and Cardiovascular Surgery
https://www.readbyqxmd.com/read/27599727/flow-measurement-at-the-aortic-root-impact-of-location-of-through-plane-phase-contrast-velocity-mapping
#20
Litten Bertelsen, Jesper Hastrup Svendsen, Lars Køber, Ketil Haugan, Søren Højberg, Carsten Thomsen, Niels Vejlstrup
BACKGROUND: Cardiovascular magnetic resonance (CMR) is considered the gold standard of cardiac volumetric measurements. Flow in the aortic root is often measured at the sinotubular junction, even though placing the slice just above valve level may be more precise. It is unknown how much flow measurements vary at different levels in the aortic root and which level corresponds best to left ventricle volumetry. METHODS: All patients were older than 70 years presenting with at least one of the following diagnoses: diabetes, hypertension, prior stroke and/or heart failure...
September 7, 2016: Journal of Cardiovascular Magnetic Resonance
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