Filters








10,936 Hits in 6.3 sec

Validation of an optical flow method for tag displacement estimation

L. Dougherty, J.C. Asmuth, A.S. Blom, L. Axel, R. Kumar
1999 IEEE Transactions on Medical Imaging  
Introduction We present an optical flow method for the rapid estimation of deformation of magnetic resonance tagged cardiac images.  ...  as an initialization, estimates the local flow vector for each point between the two images.  ... 
doi:10.1109/42.768845 pmid:10385293 fatcat:5xybkjuiirfq5poarjvqydmvlm

Deformation analysis of 3D tagged cardiac images using an optical flow method

Chun Xu, James J Pilla, Gamaliel Isaac, Joseph H Gorman, Aaron S Blom, Robert C Gorman, Zhou Ling, Lawrence Dougherty
2010 Journal of Cardiovascular Magnetic Resonance  
This study proposes and validates a method of measuring 3D strain in myocardium using a 3D Cardiovascular Magnetic Resonance (CMR) tissue-tagging sequence and a 3D optical flow method (OFM).  ...  In-vivo validation demonstrated excellent correlation between the displacement measured by manually tracking tag intersections and that generated by 3D OFM (R ≥ 0.98).  ...  The authors acknowledge the help and critiques provided by Daniel Robb, MD, during preparation of this manuscript.  ... 
doi:10.1186/1532-429x-12-19 pmid:20353600 pmcid:PMC2856559 fatcat:qdqe2zbddjdrxil5imqw63lq7a

Density tagging velocimetry

Markus Raffel, Ricardo Hernandez-Rivera, Benjamin Heine, Andreas Schröder, Karen Mulleners
2011 Experiments in Fluids  
Density Tagging Velocimetry, a novel optical technique for point-wise measurement of flow velocity is proposed here.  ...  Density Tagging Velocimetry has the potential for inflight application and is particularly suited for measuring flow velocities in regions where the use of tracer particles is difficult or undesired.  ...  Temperature of the Gas Flow In addition to the velocity measurement, the plasma tagging procedure allows for a simultaneous estimate of the temperature of gas flows.  ... 
doi:10.1007/s00348-011-1058-6 fatcat:ylznlhqs3nbcpd25x3ptluvvo4

Motion estimation of tagged cardiac magnetic resonance images using variational techniques

N. Carranza-Herrezuelo, A. Bajo, F. Sroubek, C. Santamarta, G. Cristobal, A. Santos, M.J. Ledesma-Carbayo
2010 Computerized Medical Imaging and Graphics  
This work presents a new method for motion estimation of tagged cardiac magnetic resonance sequences based on variational techniques.  ...  The variational method has been improved by adding a new term in the optical flow equation that incorporates tracking points with high stability of phase.  ...  Acknowledgments The authors thank Esther Pérez David and Manuel Desco, from the Hospital Gregorio Marañón for providing us with the CMR images.  ... 
doi:10.1016/j.compmedimag.2010.03.002 pmid:20413267 fatcat:yclobbdkgngn7kxk6orwdcajtm

In-vivo clinical validation of cardiac deformation and strain measurements from 4D ultrasound

Ming Jack Po, A Lorsakul, Qi Duan, K J Yeroushalmi, E Hyodo, Y Oe, S Homma, A F Laine
2010 2010 Annual International Conference of the IEEE Engineering in Medicine and Biology  
While many methods have been proposed for the estimation of 3D left ventricular deformation and strains derived from 4D ultrasound, currently there is a lack of in vivo clinical validation of these algorithms  ...  In this paper, we describe the experiments used in validating cardiac deformation and strain estimates of 4D ultrasound using correlation-based optical flow tracking on two different COPD patients with  ...  In this paper we describe the experiments used to validate cardiac deformation and strain estimates of RT3D ultrasound using a correlationbased optical flow tracking method.  ... 
doi:10.1109/iembs.2010.5626332 pmid:21095877 pmcid:PMC3123825 fatcat:aflt4dq7lna43cmah6s4zrl3fq

Coronary Occlusion Detection with 4D Optical Flow Based Strain Estimation on 4D Ultrasound [chapter]

Qi Duan, Elsa D. Angelini, Auranuch Lorsakul, Shunichi Homma, Jeffrey W. Holmes, Andrew F. Laine
2009 Lecture Notes in Computer Science  
This is the first direct validation study of our image analysis method for clinical diagnoses and outcome.  ...  In our previous work, a 4D optical flow based method was developed to estimate dynamic cardiac metrics, including strains anddisplacements, from 4D ultrasound.  ...  Holmes (Department of Biomedical Engineering, University of Virginia, USA) for performing the canine experiments.  ... 
doi:10.1007/978-3-642-01932-6_23 fatcat:s3bl7ek7e5gkfisn76tu5voyum

Motion Tracking and Strain Map Computation for Quasi-Static Magnetic Resonance Elastography [chapter]

Y. B. Fu, C. K. Chui, C. L. Teo, E. Kobayashi
2011 Lecture Notes in Computer Science  
Simulated tagged MR images were constructed and analyzed to validate the HARP-based method.  ...  Indentation force was recorded for soft tissue elasticity reconstruction. Motion tracking and strain map of human lower leg are calculated using a harmonic phase (HARP)-based method.  ...  Optical flow is advantageous over template matching in providing a dense estimation of the motion field instead of a sparse set of data located at the tag lines.  ... 
doi:10.1007/978-3-642-23623-5_54 fatcat:ytikeizjbjdfpa6yxjby5s55fq

Analytic signal phase-based myocardial motion estimation in tagged MRI sequences by a bilinear model and motion compensation

Liang Wang, Adrian Basarab, Patrick R. Girard, Pierre Croisille, Patrick Clarysse, Philippe Delachartre
2015 Medical Image Analysis  
signal phase-based myocardial motion estimation in tagged MRI sequences by a bilinear model and motion compensation.  ...  This work was partially supported by ANR-11-LABX-0040-CIMI in the program ANR-11-IDEX-0002-02 of the University of Toulouse and 3DSTRAIN ANR-11-TecSan-002 project.  ...  Acknowledgments This work was performed in the framework of the LABEX PRIMES (ANR-11-LABX-0063) and LABEX CELYA (ANR-10-LABX-0060) of Université de Lyon, within the program "Investissements d'Avenir" (  ... 
doi:10.1016/j.media.2015.06.005 pmid:26176412 fatcat:7i72kic465dtzhaa3zy7pnzctq

A Multi-scale Feature Based Optic Flow Method for 3D Cardiac Motion Estimation [chapter]

Alessandro Becciu, Hans van Assen, Luc Florack, Sebastian Kozerke, Vivian Roode, Bart M. ter Haar Romeny
2009 Lecture Notes in Computer Science  
Our new 3D multi-scale optic flow method is a promising technique for analyzing true 3D cardiac motion at voxel precision, and free of through-plane artifacts present in multiple-2D data sets.  ...  In this paper we investigate a new 3D aperture-problem free optic flow method to study the cardiac motion by tracking stable multi-scale features such as maxima and minima on 3D tagged MR and sine-phase  ...  Acknowledgements We would like to thank Dr Markus van Almsick for his help in Mathematica implementation.  ... 
doi:10.1007/978-3-642-02256-2_49 fatcat:gdtjc7uxnzbgrndprjycxqncnq

An Adapted Optical Flow Algorithm for Robust Quantification of Cardiac Wall Motion From Standard Cine-MR Examinations

M. Xavier, A. Lalande, P. M. Walker, F. Brunotte, L. Legrand
2012 IEEE Transactions on Information Technology in Biomedicine  
This paper presents a method for local myocardial motion estimation from a conventional SSFP cine-MRI sequence using a modified phase-based Optical Flow (OF) technique.  ...  Motion assessment using our method on cine-MR images gives promising results on motion estimation on a pixel by pixel basis, leading to a regional measurement of the timevelocity course of myocardial displacement  ...  Jean-Christophe Eicher (University Hospital of Dijon, France) and Dr. Sophiane Houamria (University Hospital of Dijon, France) for their expertise in cardiology.  ... 
doi:10.1109/titb.2012.2204893 pmid:22717523 fatcat:jqlscord65g2rpnahji6cmmcmi

Velocity Measurements in Channel Gas Flows in the Slip Regime by means of Molecular Tagging Velocimetry

Dominique Fratantonio, Marcos Rojas-Cárdenas, Christine Barrot, Lucien Baldas, Stéphane Colin
2020 Micromachines  
Direct measurements of the slip velocity in rarefied gas flows produced by local thermodynamic non-equilibrium at the wall represent crucial information for the validation of existing theoretical and numerical  ...  MTV has provided accurate measurements of the molecular displacement of the gas at average pressures of the order of 1 kPa.  ...  The channel was manufactured with (i) an optical access for the UV laser excitation of the tracer seeded in the gas flow; (ii) an optical access for capturing the phosphorescence emission of the tracer  ... 
doi:10.3390/mi11040374 pmid:32252354 pmcid:PMC7230473 fatcat:p3fjcdg4t5e6rgleiof6hqaoze

Molecular tagging velocimetry by direct phosphorescence in gas microflows: Correction of Taylor dispersion

Hacene Si Hadj Mohand, Aldo Frezzotti, Juergen J. Brandner, Christine Barrot, Stéphane Colin
2017 Experimental Thermal and Fluid Science  
The obtained results represent an encouraging step for future analysis of rarefied gas microflows.  ...  Several variants of this technique have been successfully developed for analyzing external gas flows or internal gas flows in large systems.  ...  The Reynolds number is of the order of 35 Re  and in this laminar flow regime, the estimated hydrodynamic entry length is about 3 mm, which ensures that the flow is fully developed in the tagged region  ... 
doi:10.1016/j.expthermflusci.2017.01.002 fatcat:a2qktenwurcwneenkcysgnrkke

Molecular tagging velocimetry and thermometry and its application to the wake of a heated circular cylinder

Hui Hu, Manoochehr M Koochesfahani
2006 Measurement science and technology  
The measured Lagrangian displacement of the tagged molecules provides the estimate of the fluid velocity vector.  ...  We report improvements to the molecular tagging velocimetry and thermometry (MTV&T) technique for the simultaneous measurement of velocity and temperature fields in fluid flows.  ...  Acknowledgments This work was supported by the CRC Program of the National Science Foundation, grant number CHE-0209898, and made use of shared facilities of the MRSEC Program of the National Science Foundation  ... 
doi:10.1088/0957-0233/17/6/s06 fatcat:g45zygjvvzao7kksa4lckckx5y

A gradient-based optical-flow cardiac motion estimation method for cine and tagged MR images

Liang Wang, Patrick Clarysse, Zhengjun Liu, Bin Gao, Wanyu Liu, Pierre Croisille, Philippe Delachartre
2019 Medical Image Analysis  
The results show more than 53% improvements on displacement estimation, and more than 24% on strain estimation for both C-MRI and T-MRI sequences, as compared to state-of-the-art cardiac motion estimators  ...  The tag pattern offers natural landmarks within the image that makes it possible to accurately quantify the motion within the myocardial wall. Therefore, several methods have been proposed for T-MRI.  ...  Acknowledgments This study was conducted within the framework of the LABEX PRIMES (ANR-11-LABX-0063) and LABEX CELYA (ANR-10-LABX-0060) projects of the University of Lyon, within the "Investissements d'Avenir  ... 
doi:10.1016/j.media.2019.06.016 pmid:31302510 fatcat:qnfay2xx4bfxji5fwvdkbmh74a

Depth selective acousto-optic flow measurement

Adi Tsalach, Zeev Schiffer, Eliahu Ratner, Ilan Breskin, Reuven Zeitak, Revital Shechter, Michal Balberg
2015 Biomedical Optics Express  
Optical based methods for non-invasive measurement of regional blood flow tend to incorrectly assess cerebral blood flow, due to contribution of extra-cerebral tissues to the obtained signal.  ...  We demonstrate that spectral analysis of phase-coded light signals, tagged by specific ultrasound patterns, enables differentiation of flow patterns at different depths.  ...  Herein we present a novel non-invasive method for measurement of deep tissue blood flow based on coherent NIR light scattering and the acousto-optic effect, named Ultrasound Tagged Light (UTL) [19] .  ... 
doi:10.1364/boe.6.004871 pmid:26713201 pmcid:PMC4679261 fatcat:37sp7bdz6rbj7c4zrf65fbdftu
« Previous Showing results 1 — 15 out of 10,936 results