keyword
https://read.qxmd.com/read/32873445/a-polyvinyl-alcohol-based-thermochromic-material-for-ultrasound-therapy-phantoms
#1
Simone Ambrogio, Raphaela de Melo Baêsso, Alberto Gomis, Ian Rivens, Gail Ter Haar, Bajram Zeqiri, Kumar V Ramnarine, Fiammetta Fedele, Piero Miloro
Temperature estimation is a fundamental step in assessment of the efficacy of thermal therapy. A thermochromic material sensitive within the temperature range 52.5°C-75°C has been developed. The material is based on polyvinyl alcohol cryogel with the addition of a commercial thermochromic ink. It is simple to manufacture, low cost, non-toxic and versatile. The thermal response of the material was evaluated using multiple methods, including immersion in a temperature-controlled water bath, a temperature-controlled heated needle and high-intensity focused ultrasound (HIFU) sonication...
August 29, 2020: Ultrasound in Medicine & Biology
https://read.qxmd.com/read/32524216/a-simple-realistic-walled-phantom-for-intravascular-and-intracardiac-applications
#2
Hareem Nisar, John Moore, Roberta Piazza, Efthymios Maneas, Elvis C S Chen, Terry M Peters
PURPOSE: This work aims to develop a simple, anatomically and haptically realistic vascular phantom, compatible with intravascular and intracardiac ultrasound. The low-cost, dual-layered phantom bridges the gap between traditional wall-only and wall-less phantoms by showing both the vessel wall and surrounding tissue in ultrasound imaging. This phantom can better assist clinical tool training, testing of intravascular devices, blood flow studies, and validation of algorithms for intravascular and intracardiac surgical systems...
June 10, 2020: International Journal of Computer Assisted Radiology and Surgery
https://read.qxmd.com/read/31811996/polyvinyl-alcohol-cryogel-based-vessel-mimicking-material-for-modelling-the-progression-of-atherosclerosis
#3
Andrew J Malone, Sean Cournane, Izabela G Naydenova, Andrew J Fagan, Jacinta E Browne
PURPOSE: The stiffness of Polyvinyl-alcohol cryogel can be adjusted through application of consecutive freeze-thaw cycles. This material has potential applications in the production of tissue mimicking phantoms in diagnostic ultrasound. The aim of this study was to use PVA-c to produce a range of geometrically and acoustically identical vessel phantoms modelling stages of atherosclerosis which could be verified through mechanical testing, thus allowing for more precision in quantitative in-vitro flow analysis of atherosclerosis...
December 4, 2019: Physica Medica: PM
https://read.qxmd.com/read/31128769/development-and-characterization-of-medical-phantoms-for-ultrasound-imaging-based-on-customizable-and-mouldable-polyvinyl-alcohol-cryogel-based-materials-and-3-d-printing-application-to-high-frequency-cranial-ultrasonography-in-infants
#4
Luis Elvira, Carmen Durán, Ricardo T Higuti, Marcelo M Tiago, Alberto Ibáñez, Montserrat Parrilla, Eva Valverde, Javier Jiménez, Quique Bassat
This work presents an affordable and easily customizable methodology for phantom manufacturing, which can be used to mimic different anatomic organs and structures. This methodology is based on the use of polyvinyl alcohol-based cryogels as a physical substitute for biologic soft tissues and of 3-D printed polymers for hard tissues, moulding and supporting elements. Thin and durable soft-tissue mimicking layers and multilayer arrangements can be obtained using these materials. Special attention was paid to the acoustic properties (sound speed, attenuation coefficient and mechanical impedance) of the materials developed to simulate soft tissues...
May 22, 2019: Ultrasound in Medicine & Biology
https://read.qxmd.com/read/30295670/manufacturing-abdominal-aorta-hydrogel-tissue-mimicking-phantoms-for-ultrasound-elastography-validation
#5
Doran S Mix, Michael C Stoner, Steven W Day, Michael S Richards
Ultrasound (US) elastography, or elasticity imaging, is an adjunct imaging technique that utilizes sequential US images of soft tissues to measure the tissue motion and infer or quantify the underlying biomechanical characteristics. For abdominal aortic aneurysms (AAA), biomechanical properties such as changes in the tissue's elastic modulus and estimates of the tissue stress may be essential for assessing the need for the surgical intervention. Abdominal aortic aneurysms US elastography could be a useful tool to monitor AAA progression and identify changes in biomechanical properties characteristic of high-risk patients...
September 19, 2018: Journal of Visualized Experiments: JoVE
https://read.qxmd.com/read/29685590/visualizing-angle-independent-principal-strains-in-the-longitudinal-view-of-the-carotid-artery-phantom-and-in-vivo-evaluation
#6
Rohit Nayak, Giovanni Schifitto, Marvin M Doyley
Non-invasive vascular elastography can evaluate the stiffness of the carotid artery by visualizing the vascular strain distribution. Axial strain estimates of the longitudinal cross section of the carotid artery are sensitive to the angle between the artery and the transducer. Anatomical variations in branching and arching of the carotid artery can affect the assessment of arterial stiffness. In this study, we hypothesized that principal strain elastograms computed using compounded plane wave imaging can reliably visualize the strain distribution in the carotid artery, independent of the transducer angle...
July 2018: Ultrasound in Medicine & Biology
https://read.qxmd.com/read/28961110/noninvasive-vascular-modulography-method-for-imaging-the-local-elasticity-of-atherosclerotic-plaques-simulation-and-in-vitro-vessel-phantom-study
#7
Jonathan Poree, Boris Chayer, Gilles Soulez, Jacques Ohayon, Guy Cloutier
Mechanical and morphological characterization of atherosclerotic lesions in carotid arteries remains an essential step for the evaluation of rupture prone plaques and the prevention of strokes. In this paper, we propose a noninvasive vascular imaging modulography (NIV-iMod) method, which is capable of reconstructing a heterogeneous Young's modulus distribution of a carotid plaque from the Von Mises strain elastogram. Elastograms were computed with noninvasive ultrasound images using the Lagrangian speckle model estimator and a dynamic segmentation-optimization procedure to highlight mechanical heterogeneities...
December 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://read.qxmd.com/read/28887857/development-of-a-patient-specific-atrial-phantom-model-for-planning-and-training-of-inter-atrial-interventions
#8
Pedro Morais, João Manuel R S Tavares, Sandro Queirós, Fernando Veloso, Jan D'hooge, João L Vilaça
BACKGROUND: Several authors have presented cardiac phantoms to mimic the particularities of the heart, making it suitable for medical training and surgical planning. Although the initial models were mainly focused on the ventricles, personalized phantoms of the atria were recently presented. However, such models are typically rigid, the atrial wall is not realistic and they are not compatible with ultrasound (US), being sub-optimal for planning/training of several interventions. METHODS: In this work, we propose a strategy to construct a patient-specific atrial model...
November 2017: Medical Physics
https://read.qxmd.com/read/28728780/detecting-regional-stiffness-changes-in-aortic-aneurysmal-geometries-using-pressure-normalized-strain
#9
Doran S Mix, Ling Yang, Camille C Johnson, Nathan Couper, Ben Zarras, Isaac Arabadjis, Lauren E Trakimas, Michael C Stoner, Steven W Day, Michael S Richards
Transabdominal ultrasound elasticity imaging could improve the assessment of rupture risk for abdominal aortic aneurysms by providing information on the mechanical properties and stress or strain states of vessel walls. We implemented a non-rigid image registration method to visualize the pressure-normalized strain within vascular tissues and adapted it to measure total strain over an entire cardiac cycle. We validated the algorithm's performance with both simulated ultrasound images with known principal strains and anatomically accurate heterogeneous polyvinyl alcohol cryogel vessel phantoms...
October 2017: Ultrasound in Medicine & Biology
https://read.qxmd.com/read/28331886/effects-of-line-fiducial-parameters-and-beamforming-on-ultrasound-calibration
#10
Golafsoun Ameri, John S H Baxter, A Jonathan McLeod, Terry M Peters, Elvis C S Chen
Ultrasound (US)-guided interventions are often enhanced via integration with an augmented reality environment, a necessary component of which is US calibration. Calibration requires the segmentation of fiducials, i.e., a phantom, in US images. Fiducial localization error (FLE) can decrease US calibration accuracy, which fundamentally affects the total accuracy of the interventional guidance system. Here, we investigate the effects of US image reconstruction techniques as well as phantom material and geometry on US calibration...
January 2017: Journal of Medical Imaging
https://read.qxmd.com/read/28114013/wall-less-flow-phantoms-with-tortuous-vascular-geometries-design-principles-and-a-patient-specific-model-fabrication-example
#11
Chung Kit Ho, Adrian J Y Chee, Billy Y S Yiu, Anderson C O Tsang, Kwok Wing Chow, Alfred C H Yu
Flow phantoms with anatomically realistic geometry and high acoustic compatibility are valuable investigative tools in vascular ultrasound studies. Here, we present a new framework to fabricate ultrasound-compatible flow phantoms to replicate human vasculature that is tortuous, non-planar and branching in nature. This framework is based upon the integration of rapid prototyping and investment casting principles. A pedagogical walkthrough of our engineering protocol is presented in this paper using a patient-specific cerebral aneurysm model as an exemplar demonstration...
December 6, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://read.qxmd.com/read/27959808/wall-less-flow-phantoms-with-tortuous-vascular-geometries-design-principles-and-a-patient-specific-model-fabrication-example
#12
Chung Kit Ho, Adrian J Y Chee, Billy Y S Yiu, Anderson C O Tsang, Kwok Wing Chow, Alfred C H Yu
Flow phantoms with anatomically realistic geometry and high acoustic compatibility are valuable investigative tools in vascular ultrasound studies. Here, we present a new framework to fabricate ultrasound-compatible flow phantoms to replicate human vasculature that is tortuous, nonplanar, and branching in nature. This framework is based upon the integration of rapid prototyping and investment casting principles. A pedagogical walkthrough of our engineering protocol is presented in this paper using a patient-specific cerebral aneurysm model as an exemplar demonstration...
January 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://read.qxmd.com/read/26952900/contactless-remote-induction-of-shear-waves-in-soft-tissues-using-a-transcranial-magnetic-stimulation-device
#13
Pol Grasland-Mongrain, Erika Miller-Jolicoeur, An Tang, Stefan Catheline, Guy Cloutier
This study presents the first observation of shear waves induced remotely within soft tissues. It was performed through the combination of a transcranial magnetic stimulation device and a permanent magnet. A physical model based on Maxwell and Navier equations was developed. Experiments were performed on a cryogel phantom and a chicken breast sample. Using an ultrafast ultrasound scanner, shear waves of respective amplitudes of 5 and 0.5 μm were observed. Experimental and numerical results were in good agreement...
March 21, 2016: Physics in Medicine and Biology
https://read.qxmd.com/read/26773791/high-frame-rate-and-high-line-density-ultrasound-imaging-for-local-pulse-wave-velocity-estimation-using-motion-matching-a-feasibility-study-on-vessel-phantoms
#14
Fubing Li, Qiong He, Chengwu Huang, Ke Liu, Jinhua Shao, Jianwen Luo
Pulse wave imaging (PWI) is an ultrasound-based method to visualize the propagation of pulse wave and to quantitatively estimate regional pulse wave velocity (PWV) of the arteries within the imaging field of view (FOV). To guarantee the reliability of PWV measurement, high frame rate imaging is required, which can be achieved by reducing the line density of ultrasound imaging or transmitting plane wave at the expense of spatial resolution and/or signal-to-noise ratio (SNR). In this study, a composite, full-view imaging method using motion matching was proposed with both high temporal and spatial resolution...
April 2016: Ultrasonics
https://read.qxmd.com/read/26736851/a-wall-less-poly-vinyl-alcohol-cryogel-flow-phantom-with-accurate-scattering-properties-for-transcranial-doppler-ultrasound-propagation-channels-analysis
#15
Alexander J Weir, Robin Sayer, Cheng-Xiang Wang, Stuart Parks
Medical phantoms are frequently required to verify image and signal processing systems, and are often used to support algorithm development for a wide range of imaging and blood flow assessments. A phantom with accurate scattering properties is a crucial requirement when assessing the effects of multi-path propagation channels during the development of complex signal processing techniques for Transcranial Doppler (TCD) ultrasound. The simulation of physiological blood flow in a phantom with tissue and blood equivalence can be achieved using a variety of techniques...
August 2015: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://read.qxmd.com/read/24495438/endovascular-shear-strain-elastography-for-the-detection-and-characterization-of-the-severity-of-atherosclerotic-plaques-in-vitro-validation-and-in-vivo-evaluation
#16
Younes Majdouline, Jacques Ohayon, Zahra Keshavarz-Motamed, Marie-Hélène Roy Cardinal, Damien Garcia, Louise Allard, Sophie Lerouge, Frédéric Arsenault, Gilles Soulez, Guy Cloutier
This work explores the potential of shear strain elastograms to identify vulnerable atherosclerotic plaques. The Lagrangian speckle model estimator (LSME) elasticity imaging method was further developed to estimate shear strain elasticity (SSE). Three polyvinyl alcohol cryogel vessel phantoms were imaged with an intravascular ultrasound (IVUS) scanner. The estimated SSE maps were validated against finite-element results. Atherosclerosis was induced in carotid arteries of eight Sinclair mini-pigs using a combination of surgical techniques, diabetes and a high-fat diet...
May 2014: Ultrasound in Medicine & Biology
https://read.qxmd.com/read/23366603/a-biventricular-multimodal-mri-ultrasound-cardiac-phantom
#17
Vahid Tavakoli, M J Negahdar, Michael Kendrick, Motaz Alshaher, Marcus Stoddard, Amir A Amini
A cardiac phantom can be of crucial importance in the development and validation of ultrasound and cardiac magnetic resonance (MR) imaging and image analysis methods. A biventricular multimodal cardiac phantom has been manufactured in-house that can simulate normal and pathologic hearts with different degrees of infarction. The two-chamber structure can simulate the asymmetric left ventricular motion. Poly Vinyl Alcohol (PVA) is utilized as the basic material since it can simulate the shape, elasticity, and MR and ultrasound properties of the heart...
2012: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://read.qxmd.com/read/22643042/the-effects-of-fatty-deposits-on-the-accuracy-of-the-fibroscan%C3%A2-%C3%A2-liver-transient-elastography-ultrasound-system
#18
S Cournane, J E Browne, A J Fagan
A new generation of ultrasound transient elastography (TE) systems have emerged which exploit the well-known correlation between the liver's pathological and mechanical properties through measurements of the Young's elastic modulus; however, little work has been carried out to examine the effect that fatty deposits may have on the TE measurement accuracy. An investigation was carried out on the effects on the measurement accuracy of a TE ultrasound system, the Fibroscan®, caused by overlaying fat layers of varying thickness on healthy liver-mimicking phantoms, simulating in vivo conditions for obese patients...
June 21, 2012: Physics in Medicine and Biology
https://read.qxmd.com/read/22447435/validation-of-a-hybrid-doppler-ultrasound-vessel-based-registration-algorithm-for-neurosurgery
#19
Sean Jy-Shyang Chen, Ingerid Reinertsen, Pierrick Coupé, Charles X B Yan, Laurence Mercier, D Rolando Del Maestro, D Louis Collins
PURPOSE: We describe and validate a novel hybrid nonlinear vessel registration algorithm for intra-operative updating of preoperative magnetic resonance (MR) images using Doppler ultrasound (US) images acquired on the dura for the correction of brain-shift and registration inaccuracies. We also introduce an US vessel appearance simulator that generates vessel images similar in appearance to that acquired with US from MR angiography data. METHODS: Our registration uses the minimum amount of preprocessing to extract vessels from the raw volumetric images...
September 2012: International Journal of Computer Assisted Radiology and Surgery
https://read.qxmd.com/read/22225325/an-anthropomorphic-polyvinyl-alcohol-brain-phantom-based-on-colin27-for-use-in-multimodal-imaging
#20
Sean Jy-Shyang Chen, Pierre Hellier, Maud Marchal, Jean-Yves Gauvrit, Romain Carpentier, Xavier Morandi, D Louis Collins
PURPOSE: In this paper, the method for the creation of an anatomically and mechanically realistic brain phantom from polyvinyl alcohol cryogel (PVA-C) is proposed for validation of image processing methods such as segmentation, reconstruction, registration, and denoising. PVA-C is material widely used in medical imaging phantoms because of its mechanical similarities to soft tissues. METHODS: The phantom was cast in a mold designed using the left hemisphere of the Colin27 brain dataset [C...
January 2012: Medical Physics
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