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Computational fluid dynamics

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https://www.readbyqxmd.com/read/28110403/delayed-asymptomatic-coil-migrations-toward-different-arteries-after-aneurysmal-embolization-case-report
#1
Tomoya Kamide, Kouichi Misaki, Iku Nambu, Masanao Mohri, Naoyuki Uchiyama, Mitsutoshi Nakada
Delayed coil migration after endovascular treatment with detachable coils, particularly several months after treatment, is extremely rare. In this report, the authors describe a 77-year-old female in whom delayed coil migration to the anterior cerebral artery and posterior communicating artery (PCoA) developed 3 months after an uncomplicated aneurysm embolization. The patient was successfully retreated with a closed-cell stent. Computational fluid dynamics (CFD) revealed high wall shear stress (WSS) and multiple vortices in the residual cavity of the initially treated aneurysm...
January 21, 2017: Acta Neurochirurgica
https://www.readbyqxmd.com/read/28109933/integrating-ct-myocardial-perfusion-and-ct-ffr-in-the-work-up-of-coronary-artery%C3%A2-disease
#2
Adriaan Coenen, Alexia Rossi, Marisa M Lubbers, Akira Kurata, Atsushi K Kono, Raluca G Chelu, Sabrina Segreto, Marcel L Dijkshoorn, Andrew Wragg, Robert-Jan M van Geuns, Francesca Pugliese, Koen Nieman
OBJECTIVES: The aim of this study was to investigate the individual and combined accuracy of dynamic computed tomography (CT) myocardial perfusion imaging (MPI) and computed tomography angiography (CTA) fractional flow reserve (FFR) for the identification of functionally relevant coronary artery disease (CAD). BACKGROUND: Coronary CTA has become an established diagnostic test for ruling out CAD, but it does not allow interpretation of the hemodynamic severity of stenotic lesions...
January 12, 2017: JACC. Cardiovascular Imaging
https://www.readbyqxmd.com/read/28108202/evaluation-of-coronary-flow-conditions-in-complex-coronary-artery-bifurcations-stenting-using-computational-fluid-dynamics-impact-of-final-proximal-optimization-technique-on-different-double-stent-techniques
#3
Gianluca Rigatelli, Marco Zuin, Fabio Dell'Avvocata, Dobrin Vassilev, Ramesh Daggubati, Thach Nguyen, Nguyen Van Viet Thang, Nicolas Foin
BACKGROUND/PURPOSE: Computational fluid dynamics (CFD) have been recently adopted in many fields of cardiovascular medicine and in interventional cardiology. Using CFD analysis we compared the use of different PCI procedures, with and without the utilization of a proximal optimization technique (POT), on a complex coronary artery bifurcation. METHODS/MATERIALS: For the analysis, we considered a hypothetic model of a left anterior descending artery-diagonal Medina 1,1,1 bifurcation type with a diameter of the proximal main branch (MB) and the side branch (SB) set at 3...
January 9, 2017: Cardiovascular Revascularization Medicine: Including Molecular Interventions
https://www.readbyqxmd.com/read/28107552/reflections-on-the-history-of-indoor-air-science-focusing-on-the-last-50-years
#4
Jan Sundell
The scientific articles and Indoor Air conference publications of the indoor air sciences (IAS) during the last 50 years are summarized. In total 7524 presentations, from 79 countries, have been made at Indoor Air conferences held between 1978 (49 presentations) and 2014 (1049 presentations). In the Web of Science 26,992 articles on indoor air research (with the word "indoor" as a search term) have been found (as of 1 Jan 2016) of which 70% were published during the last 10 years. The modern scientific history started in the 1970s with a question: "did indoor air pose a threat to health as did outdoor air?" Soon it was recognized that indoor air is more important, from a health point of view, than outdoor air...
January 20, 2017: Indoor Air
https://www.readbyqxmd.com/read/28106892/theoretical-study-on-the-need-for-laser-iridotomy-in-an-implantable-collamer-lens-with-a-hole-using-computational-fluid-dynamics
#5
T Kawamorita, K Shimizu, N Shoji
PurposeAlthough one of the advantages of the Hole-ICL implantation is that laser iridotomy (LI) is unnecessary, the evidence have not been reported from the viewpoint of aqueous humor circulation. We investigated the effect of laser iridotomy (LI) on the fluid dynamics of aqueous humor in an implantable collamer lens (ICL) with a central hole, that is, a Hole-ICL using computational fluid dynamics.MethodsA fluid dynamics simulation was performed using the thermal-hydraulic analysis software FloEFD (Mentor Graphics Corp...
January 20, 2017: Eye
https://www.readbyqxmd.com/read/28099023/computational-models-of-the-gastrointestinal-environment-1-the-effect-of-digestion-on-the-phase-behaviour-of-intestinal-fluids
#6
Woldeamanuel A Birru, Dallas B Warren, Stephen J Headey, Hassan Benameur, Christopher J H Porter, Colin W Pouton, David K Chalmers
Improved models of the gastrointestinal environment have great potential to assist the complex process of drug formulation. Molecular dynamics (MD) is a powerful method for investigating phase behaviour at a molecular level. In this study we use multiple MD simulations to calculate phase diagrams for bile before and after digestion. In these computational models, undigested bile is represented by mixtures of palmitoyl-oleoylphosphatidylcholine (POPC), sodium glycodeoxycholate (GDX) and water. Digested bile is modelled using a 1:1 mixture of oleic acid and palmitoylphosphatidylcholine (lyso-phosphatidylcholine, LPC), GDX and water...
January 18, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28095764/evaluation-of-the-carotid-artery-stenosis-based-on-minimization-of-mechanical-energy-loss-of-the-blood-flow
#7
Sheau Fung Sia, Xihai Zhao, Rui Li, Yu Zhang, Winston Chong, Le He, Yu Chen
BACKGROUND: Internal carotid artery stenosis requires an accurate risk assessment for the prevention of stroke. Although the internal carotid artery area stenosis ratio at the common carotid artery bifurcation can be used as one of the diagnostic methods of internal carotid artery stenosis, the accuracy of results would still depend on the measurement techniques. The purpose of this study is to propose a novel method to estimate the effect of internal carotid artery stenosis on the blood flow based on the concept of minimization of energy loss...
November 2016: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine
https://www.readbyqxmd.com/read/28092136/computational-fluid-dynamic-modeling-of-nose-to-ceiling-head-positioning-for-sphenoid-sinus-irrigation
#8
John R Craig, James N Palmer, Kai Zhao
BACKGROUND: After sinus surgery, patients are commonly instructed to irrigate with saline irrigations with their heads over a sink and noses directed inferiorly (nose-to-floor). Although irrigations can penetrate the sinuses in this head position, no study has assessed whether sphenoid sinus penetration can be improved by irrigating with the nose directed superiorly (nose-to-ceiling). The purpose of this study was to use a validated computational fluid dynamics (CFD) model of sinus irrigations to assess the difference in sphenoid sinus delivery of irrigations after irrigating in a nose-to-floor vs nose-to-ceiling head position...
January 16, 2017: International Forum of Allergy & Rhinology
https://www.readbyqxmd.com/read/28090122/effect-of-static-vs-dynamic-imaging-on-particle-transport-in-ct-based-numerical-models-of-human-central-airways
#9
Shinjiro Miyawaki, Eric A Hoffman, Ching-Long Lin
Advances in quantitative computed tomography (CT) has provided methods to assess the detailed structure of the pulmonary airways and parenchyma, providing the means of applying computational fluid dynamics-based modeling to better understand subject-specific differences in structure-to-function relationships. Most of the previous numerical studies, seeking to predict patterns of inhaled particle deposition, have considered airway geometry and regional ventilation derived from static images. Because geometric alterations of the airway and parenchyma associated with regional ventilation may greatly affect particle transport, we have sought to investigate the effect of rigid vs...
October 2016: Journal of Aerosol Science
https://www.readbyqxmd.com/read/28089607/estimates-of-nasal-airflow-at-the-nasal-cycle-mid-point-improve-the-correlation-between-objective-and-subjective-measures-of-nasal-patency
#10
Courtney Gaberino, John S Rhee, Guilherme J M Garcia
INTRODUCTION: The nasal cycle represents a significant challenge when comparing pre- and post-surgery objective measures of nasal airflow. METHODS: Computational fluid dynamics (CFD) simulations of nasal airflow were conducted in 12 nasal airway obstruction patients showing significant nasal cycling between pre- and post-surgery computed tomography scans. To correct for the nasal cycle, mid-cycle models were created virtually. Subjective scores of nasal patency were obtained via the Nasal Obstruction Symptom Evaluation (NOSE) and unilateral visual analog scale (VAS)...
January 9, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28088305/inertial-particle-dynamics-in-large-artery-flows-implications-for-modeling-arterial-embolisms
#11
Debanjan Mukherjee, Shawn C Shadden
The complexity of inertial particle dynamics through swirling chaotic flow structures characteristic of pulsatile large-artery hemodynamics renders significant challenges in predictive understanding of transport of such particles. This is specifically crucial for arterial embolisms, where knowledge of embolus transport to major vascular beds helps in disease diagnosis and surgical planning. Using a computational framework built upon image-based CFD and discrete particle dynamics modeling, a multi-parameter sampling-based study was conducted on embolic particle dynamics and transport...
December 29, 2016: Journal of Biomechanics
https://www.readbyqxmd.com/read/28078380/imaging-features-of-hepatic-sarcomatous-carcinoma-on-computed-tomography-and-gadoxetic-acid-enhanced-magnetic-resonance-imaging
#12
Kyo-Won Gu, Young Kon Kim, Ji Hye Min, Sang Yun Ha, Woo Kyoung Jeong
PURPOSE: To determine the imaging features of hepatic sarcomatous carcinoma including sarcomatous intrahepatic cholangiocarcinoma (S-ICC) and sarcomatous hepatocellular carcinoma (S-HCC) on computed tomography (CT) and gadoxetic acid-enhanced magnetic resonance imaging (MRI). MATERIALS AND METHODS: Twenty-four patients with pathologically confirmed S-ICCs (n = 13), S-HCCs (n = 7), sarcomatous carcinoma (n = 2), carcinosarcoma (n = 1), and sarcomatous combined HCC-CC (n = 1) (size range 2...
January 12, 2017: Abdominal Radiology
https://www.readbyqxmd.com/read/28078170/computational-fluid-dynamics-assisted-characterization-of-parafoveal-hemodynamics-in-normal-and-diabetic-eyes-using-adaptive-optics-scanning-laser-ophthalmoscopy
#13
Yang Lu, Miguel O Bernabeu, Jan Lammer, Charles C Cai, Martin L Jones, Claudio A Franco, Lloyd Paul Aiello, Jennifer K Sun
Diabetic retinopathy (DR) is the leading cause of visual loss in working-age adults worldwide. Previous studies have found hemodynamic changes in the diabetic eyes, which precede clinically evident pathological alterations of the retinal microvasculature. There is a pressing need for new methods to allow greater understanding of these early hemodynamic changes that occur in DR. In this study, we propose a noninvasive method for the assessment of hemodynamics around the fovea (a region of the eye of paramount importance for vision)...
December 1, 2016: Biomedical Optics Express
https://www.readbyqxmd.com/read/28075194/aerosol-drug-delivery-during-noninvasive-positive-pressure-ventilation-effects-of-intersubject-variability-and-excipient-enhanced-growth
#14
Ross L Walenga, P Worth Longest, Anubhav Kaviratna, Michael Hindle
BACKGROUND: Nebulized aerosol drug delivery during the administration of noninvasive positive pressure ventilation (NPPV) is commonly implemented. While studies have shown improved patient outcomes for this therapeutic approach, aerosol delivery efficiency is reported to be low with high variability in lung-deposited dose. Excipient enhanced growth (EEG) aerosol delivery is a newly proposed technique that may improve drug delivery efficiency and reduce intersubject aerosol delivery variability when coupled with NPPV...
January 11, 2017: Journal of Aerosol Medicine and Pulmonary Drug Delivery
https://www.readbyqxmd.com/read/28069165/on-the-quantification-and-visualization-of-transient-periodic-instabilities-in-pulsatile-flows
#15
Muhammad Owais Khan, Christophe Chnafa, Diego Gallo, Filippo Molinari, Umberto Morbiducci, David A Steinman, Kristian Valen-Sendstad
Turbulent-like flows without cycle-to-cycle variations are more frequently being reported in studies of cardiovascular flows. The associated stimuli might be of mechanobiological relevance, but how to quantify them objectively is not obvious. Classical Reynolds decomposition, where the flow is separated into mean and fluctuating velocity components, is not applicable as the phase-average is zero. We therefore expanded on established techniques and present the idea, analogous to Reynolds decomposition, to decompose a flow with transient instabilities into low- versus high frequency components, respectively, to discriminate flow instabilities from the underlying cardiac pulsatility...
December 31, 2016: Journal of Biomechanics
https://www.readbyqxmd.com/read/28067615/intracranial-atherosclerosis-from-anatomy-to-pathophysiology
#16
Yuehua Pu, Linfang Lan, Xinyi Leng, Lawrence Ks Wong, Liping Liu
Background Intracranial atherosclerotic stenosis is an important etiology subtype of ischemic stroke. Stenosis severity was thought to be the main reference index for clinical treatment and research. However, stenosis could not reflect the ischemia risk completely, instead the hemodynamic state across the lesion, the extent of collateral circulation, and perfusion impairment downstream the stenosis are more important. Aims We write this review aimed to summarize novel angiographic methods applied in the evaluation of functional severity of ICAS, and commented on their limitations and prospects in future research...
January 1, 2017: International Journal of Stroke: Official Journal of the International Stroke Society
https://www.readbyqxmd.com/read/28063468/computational-fluid-dynamics-and-aortic-thrombus-formation-following-thoracic-endovascular-aortic-repair
#17
Foeke J H Nauta, Kevin D Lau, Christopher J Arthurs, Kim A Eagle, David M Williams, Santi Trimarchi, Himanshu J Patel, Carlos A Figueroa
BACKGROUND: We present the possible utility of computational fluid dynamics in the assessment of thrombus formation and virtual surgical planning illustrated in a patient with aortic thrombus in a kinked ascending aortic graft following thoracic endovascular aortic repair. METHODS: A patient-specific three-dimensional model was built from computed tomography. Additionally, we modeled 3 virtual aortic interventions to assess their effect on thrombosis potential: (1) open surgical repair, (2) conformable endografting, and (3) single-branched endografting...
January 4, 2017: Annals of Thoracic Surgery
https://www.readbyqxmd.com/read/28062122/airflow-behavior-changes-in-upper-airway-caused-by-different-head-and-neck-positions-comparison-by-computational-fluid-dynamics
#18
Wei Wei, Shi-Wei Huang, Lian-Hua Chen, Yang Qi, Yi-Min Qiu, Shi-Tong Li
The feasibility of computational fluid dynamics (CFD) to evaluate airflow characteristics in different head and neck positions has not been established. This study compared the changes in volume and airflow behavior of the upper airway by CFD simulation to predict the influence of anatomical and physiological airway changes due to different head-neck positions on mechanical ventilation. One awake volunteer with no risk of difficult airway underwent computed tomography in neutral position, extension position (both head and neck extended), and sniffing position (head extended and neck flexed)...
December 29, 2016: Journal of Biomechanics
https://www.readbyqxmd.com/read/28059781/wing-kinematics-measurement-and-aerodynamics-of-a-dragonfly-in-turning-flight
#19
Chengyu Li, Haibo Dong
This study integrates high-speed photogrammetry, three-dimensional surface reconstruction, and computational fluid dynamics to explore a dragonfly (Erythemis Simplicicollis) in free flight. Asymmetric wing kinematics and the associated aerodynamic characteristics of a turning dragonfly are analyzed in detail. Quantitative measurements of wing kinematics show that compared to the outer wings, the inner wings sweep more slowly with a higher angle of attack during the downstroke, whereas they flap faster with a lower angle of attack during the upstroke...
January 6, 2017: Bioinspiration & Biomimetics
https://www.readbyqxmd.com/read/28057633/compacting-a-single-flow-diverter-versus-overlapping-flow-diverters-for-intracranial-aneurysms-a-computational-study
#20
R J Damiano, V M Tutino, N Paliwal, D Ma, J M Davies, A H Siddiqui, H Meng
BACKGROUND AND PURPOSE: Locally compacting the mesh of a flow diverter by a dynamic push-pull technique can accelerate intracranial aneurysm healing. We asked how this deployment strategy compares with overlapping 2 flow diverters for aneurysmal flow reduction. MATERIALS AND METHODS: Using a high-fidelity virtual stent placement method, we simulated 3 flow-diverter strategies (single noncompacted, 2 overlapped, and single compacted) in 3 aneurysms (fusiform, large saccular, and medium saccular)...
January 5, 2017: AJNR. American Journal of Neuroradiology
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