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https://www.readbyqxmd.com/read/29604493/increasing-the-field-of-view-of-row-column-addressed-ultrasound-transducers-implementation-of-a-diverging-compound-lens
#1
Mathias Engholm, Christopher Beers, Hamed Bouzari, Jørgen Arendt Jensen, Erik Vilain Thomsen
The purpose of this work is to investigate compound lenses for row-column-addressed (RCA) ultrasound transducers for increasing the field-of-view (FOV) to a curvilinear volume region, while retaining a flat sole to avoid trapping air between the transducer sole and the patient, which would otherwise lead to unwanted reflections. The primary motivation behind this research is to develop a RCA ultrasound transducer for abdominal or cardiac imaging, where a curvilinear volume region is a necessity. RCA transducers provide 3-D ultrasound imaging with fewer channels than fully-addressed 2-D arrays (2N instead of N2 ), but they have inherently limited FOV...
March 24, 2018: Ultrasonics
https://www.readbyqxmd.com/read/29525227/silicone-based-composite-materials-simulate-breast-tissue-to-be-used-as-ultrasonography-training-phantoms
#2
Burcin Ustbas, Deniz Kilic, Ayhan Bozkurt, Mustafa Erkin Aribal, Ozge Akbulut
A silicone-based composite breast phantom is fabricated to be used as an education model in ultrasonography training. A matrix of silicone formulations is tracked to mimic the ultrasonography and tactile response of human breast tissue. The performance of two different additives: (i) silicone oil and (ii) vinyl-terminated poly (dimethylsiloxane) (PDMS) are monitored by a home-made acoustic setup. Through the use of 75 wt% vinyl-terminated PDMS in two-component silicone elastomer mixture, a sound velocity of 1...
March 2, 2018: Ultrasonics
https://www.readbyqxmd.com/read/29505403/ultrasound-imaging-from-sparse-rf-samples-using-system-point-spread-functions
#3
Colas Schretter, Shaun Bundervoet, David Blinder, Ann Dooms, Jan D'hooge, Peter Schelkens
Upcoming phased-array 2-D sensors will soon enable fast high-definition 3-D ultrasound imaging. Currently, the communication of raw radio-frequency (RF) channel data from the probe to the computer for digital beamforming is a bottleneck. For reducing the amount of transferred data samples, this paper investigates the design of an adapted sparse sampling technique for image reconstruction inspired by the compressed sensing framework. Echo responses from isolated points are generated using a physically based simulation of ultrasound wave propagation through tissues...
March 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/29467432/printed-receive-coils-with-high-acoustic-transparency-for-magnetic-resonance-guided-focused-ultrasound
#4
Joseph Corea, Patrick Ye, Dongjin Seo, Kim Butts-Pauly, Ana Claudia Arias, Michael Lustig
In magnetic resonance guided focused ultrasound (MRgFUS) therapy sound waves are focused through the body to selectively ablate difficult to access lesions and tissues. A magnetic resonance imaging (MRI) scanner non-invasively tracks the temperature increase throughout the tissue to guide the therapy. In clinical MRI, tightly fitted hardware comprised of multichannel coil arrays are required to capture high quality images at high spatiotemporal resolution. Ablating tissue requires a clear path for acoustic energy to travel but current array materials scatter and attenuate acoustic energy...
February 21, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29462704/enhancement-of-endocannabinoid-dependent-depolarization-induced-suppression-of-excitation-in-glycinergic-neurons-by-prolonged-exposure-to-high-doses-of-salicylate
#5
João Zugaib, Ricardo M Leão
The Dorsal Cochlear Nucleus (DCN) is a region which has been traditionally linked to the genesis of tinnitus, the constant perception of a phantom sound. Sodium salicylate, a COX-2 inhibitor, can induce tinnitus in high doses. Hyperactivity of DCN neurons is observed in several animal models of tinnitus, including salicylate-induced tinnitus. The DCN presents several forms of endocannabinoid (EC) dependent synaptic plasticity and COX-2 can also participate in the oxidative degradation of ECs. We recently demonstrated that short-term perfusion of sodium salicylate and other inhibitors of both oxidative and hydrolytic EC degradation did not affect depolarization-induced suppression of excitation (DSE), a form of EC- dependent short-term synaptic plasticity...
February 17, 2018: Neuroscience
https://www.readbyqxmd.com/read/29429190/-research-progress-of-functional-magnetic-resonance-imaging-in-mechanism-studies-of-tinnitus
#6
B B Ji, M Li, J N Zhang
Tinnitus is a subjective symptom of phantom sound in the ear or brain without sound or electrical stimulation in the environment. The mechanism of tinnitus is complicated and mostly unclear. Recent studies suggested that the abnormal peripheral auditory input lead to neuroplasticity changes in central nervous system followed by tinnitus. More research concerned on the tinnitus central mechanism. A rapid development of functional magnetic resonance imaging (fMRI) technique made it more widely used in tinnitus central mechanism research...
February 7, 2018: Zhonghua Er Bi Yan Hou Tou Jing Wai Ke za Zhi, Chinese Journal of Otorhinolaryngology Head and Neck Surgery
https://www.readbyqxmd.com/read/29410199/effect-of-distress-on-transient-network-dynamics-and-topological-equilibrium-in-phantom-sound-perception
#7
Anusha Mohan, Sandra Jovanovic Alexandra, Cliff V Johnson, Dirk De Ridder, Sven Vanneste
Distress is a domain-general behavioral symptom whose neural correlates have been under investigation for a long time now. Although some studies suggest that distress is encoded by changes in alpha activity and functional connectivity between specific brain regions, no study that we know has delved into the whole brain temporal dynamics of the distress component. In the current study, we compare the changes in the mean and variance of functional connectivity and small-worldness parameter over 3 min of resting state EEG to analyze the fluctuation in transient stable states, and network structure...
February 1, 2018: Progress in Neuro-psychopharmacology & Biological Psychiatry
https://www.readbyqxmd.com/read/29390736/effects-of-vibratory-pile-driver-noise-on-echolocation-and-vigilance-in-bottlenose-dolphins-tursiops-truncatus
#8
Brian K Branstetter, Victoria F Bowman, Dorian S Houser, Megan Tormey, Patchouly Banks, James J Finneran, Keith Jenkins
Vibratory pile drivers, used for marine construction, can produce sustained, high sound pressure levels (SPLs) in areas that overlap with dolphin habitats. Dolphins rely on echolocation for navigation, detecting predators and prey, and to coordinate group behavior. This study examined the effects of vibratory pile driver noise on dolphin sustained target detection capabilities through echolocation. Five dolphins were required to scan their enclosure and indicate the occurrences of phantom echoes during five different source levels of vibratory pile driver playback sound (no-playback control, 110, 120, 130, and 140 dB re 1 μPa)...
January 2018: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/29379866/combination-of-interaural-level-and-time-difference-in-azimuthal-sound-localization-in-owls
#9
Lutz Kettler, Hannah Griebel, Roland Ferger, Hermann Wagner
A function of the auditory system is to accurately determine the location of a sound source. The main cues for sound location are interaural time (ITD) and level (ILD) differences. Humans use both ITD and ILD to determine the azimuth. Thus far, the conception of sound localization in barn owls was that their facial ruff and asymmetrical ears generate a two-dimensional grid of ITD for azimuth and ILD for elevation. We show that barn owls also use ILD for azimuthal sound localization when ITDs are ambiguous. For high-frequency narrowband sounds, midbrain neurons can signal multiple locations, leading to the perception of an auditory illusion called a phantom source...
November 2017: ENeuro
https://www.readbyqxmd.com/read/29325874/perceptual-changes-with-monopolar-and-phantom-electrode-stimulation
#10
Silke Klawitter, David M Landsberger, Andreas Büchner, Waldo Nogueira
Phantom electrode (PE) stimulation is achieved by simultaneously stimulating out-of-phase from two adjacent intra-cochlear electrodes with different amplitudes. If the basal electrode stimulates with a smaller amplitude than the apical electrode of the pair, the resulting electrical field is pushed away from the basal electrode producing a lower pitch. There is great interest in using PE stimulation in a processing strategy as it can be used to provide stimulation to regions of the cochlea located more apically than the most apical contact on the electrode array...
March 2018: Hearing Research
https://www.readbyqxmd.com/read/29277451/acoustic-properties-of-small-animal-soft-tissue-in-the-frequency-range-12-32-mhz
#11
Adela Rabell-Montiel, Adrian J Thomson, Tom A Anderson, Stephen D Pye, Carmel M Moran
Quality assurance phantoms are made of tissue-mimicking materials (TMMs) the acoustic properties of which mimic those of soft tissue. However, the acoustic properties of many soft tissue types have not been measured at ultrasonic frequencies >9 MHz. With the increasing use of high-frequency ultrasound for both clinical and pre-clinical applications, it is of increasing interest to ensure that TMMs accurately reflect the acoustic properties of soft tissue at these higher frequencies. In this study, the acoustic properties of ex vivo brain, liver and kidney samples from 50 mice were assessed in the frequency range 12-32 MHz...
March 2018: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/29241704/development-and-characterization-of-an-anthropomorphic-breast-phantom-for-permanent-breast-seed-implant-brachytherapy-credentialing
#12
Michael Roumeliotis, Sarah Quirk, Matthew Skarsgard, Tiana Trumpour, Elizabeth Watt, Tyler Meyer
PURPOSE: To develop an anthropomorphic breast phantom for use in credentialing of permanent breast seed implant brachytherapy. METHODS AND MATERIALS: A representative external contour and target volume was used as the basis of mold manufacturing for anthropomorphic breast phantom development. Both target and normal tissue were composed of gel-like materials that provide suitable computed tomography and ultrasound contrast for brachytherapy delivery. The phantoms were evaluated for consistency in construction (target location) and Hounsfield unit (computed tomography contrast)...
March 2018: Brachytherapy
https://www.readbyqxmd.com/read/29192507/effect-of-transcranial-direct-current-stimulation-in-patients-with-tinnitus-a-meta-analysis-and-systematic-review
#13
REVIEW
Tang-Chuan Wang, Richard S Tyler, Ta-Yuan Chang, Jui-Cheng Chen, Chia-Der Lin, Hsiung-Kwang Chung, Yung-An Tsou
OBJECTIVES: Subjective tinnitus is a phantom sensation experienced without any external source of sound that profoundly impacts the quality of life. Some investigations have claimed that transcranial direct current stimulation (tDCS) reduces tinnitus, but studies on tDCS have demonstrated variable results. This meta-analysis aimed to examine the effect of tDCS on patients with tinnitus. METHODS: We searched for articles published through January 5, 2016, in Medline, Cochrane, EMBASE, and Google Scholar using the following keywords: tinnitus, transcranial direct current stimulation, and tDCS...
February 2018: Annals of Otology, Rhinology, and Laryngology
https://www.readbyqxmd.com/read/29185067/phantom-validation-of-quantitative-y-90-pet-ct-based-dosimetry-in-liver-radioembolization
#14
Marco D'Arienzo, Maria Pimpinella, Marco Capogni, Vanessa De Coste, Luca Filippi, Emiliano Spezi, Nick Patterson, Francesca Mariotti, Paolo Ferrari, Paola Chiaramida, Michael Tapner, Alexander Fischer, Timo Paulus, Roberto Pani, Giuseppe Iaccarino, Marco D'Andrea, Lidia Strigari, Oreste Bagni
BACKGROUND: PET/CT has recently been shown to be a viable alternative to traditional post-infusion imaging methods providing good quality images of90 Y-laden microspheres after selective internal radiation therapy (SIRT). In the present paper, first we assessed the quantitative accuracy of90 Y-PET using an anthropomorphic phantom provided with lungs, liver, spine, and a cylindrical homemade lesion located into the hepatic compartment. Then, we explored the accuracy of different computational approaches on dose calculation, including (I) direct Monte Carlo radiation transport using Raydose, (II) Kernel convolution using Philips Stratos, (III) local deposition algorithm, (IV) Monte Carlo technique (MCNP) considering a uniform activity distribution, and (V) MIRD (Medical Internal Radiation Dose) analytical approach...
November 28, 2017: EJNMMI Research
https://www.readbyqxmd.com/read/29160776/proton-range-verification-in-homogeneous-materials-through-acoustic-measurements
#15
Wei Nie, Kevin C Jones, Scott Petro, Alireza Kassaee, Chandra M Sehgal, Stephen Avery
Clinical proton beam quality assurance (QA) requires a simple and accurate method to measure the proton beam Bragg peak (BP) depth. Protoacoustics, the measurement of the pressure waves emitted by thermal expansion resulting from proton dose deposition, may be used to obtain the depth of the BP in a phantom by measuring the time-of-flight of the pressure wave. Rectangular and cylindrical phantoms of different materials (aluminum, lead, and polyethylene) were used for protoacoustic studies. Four different methods for analyzing the protoacoustic signals are compared...
January 17, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29092614/the-production-of-phantom-partials-due-to-nonlinearities-in-the-structural-components-of-the-piano
#16
Eric Rokni, Lauren M Neldner, Camille Adkison, Thomas R Moore
Phantom partials are anomalous overtones in the spectrum of the piano sound that occur at sum and difference frequencies of the natural overtones of the string. Although they are commonly assumed to be produced by forced longitudinal waves in the string, analysis of the sound of a piano produced by mechanically vibrating the soundboard while all the strings are damped indicates that phantom partials can occur in the absence of string motion. The magnitude of the effect leads to the conclusion that nonlinearity in the non-string components may be responsible for some of the power in the phantom partials...
October 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/29080282/assessment-of-the-effect-of-strontium-lead-and-aluminum-in-bone-on-dual-energy-x-ray-absorptiometry-and-quantitative-ultrasound-measurements-a-phantom-study
#17
Deok Hyun Jang, Eric Da Silva, Jahan Tavakkoli, Lubomira Slatkovska, Angela M Cheung, Ana Pejović-Milić
PURPOSE: Dual-energy X-ray absorptiometry (DXA) is the gold standard technique to measure areal bone mineral density (aBMD) for the diagnosis of osteoporosis. Because DXA relies on the attenuation of photon to estimate aBMD, deposition of bone-seeking metallic elements such as strontium, lead, and aluminum that differ in atomic numbers from calcium can cause inaccurate estimation of aBMD. Quantitative ultrasound (QUS) is another technique available to assess bone health by measuring broadband ultrasound attenuation (BUA), speed of sound (SOS), and an empirically derived quantity called stiffness index (SI)...
January 2018: Medical Physics
https://www.readbyqxmd.com/read/29071034/alterations-in-auditory-electrophysiological-responses-associated-with-temporary-suppression-of-tinnitus-induced-by-low-level-laser-therapy-a-before-after-case-series
#18
Katayoon Montazeri, Saeid Mahmoudian, Zahra Razaghi, Mohammad Farhadi
Introduction: Tinnitus is the phantom auditory perception of sound in the absence of an external or internal acoustic stimulus. The treatment is difficult due to multiple etiologies and great psychological influence. The purpose of this study was to determine alterations in auditory physiological and electrophysiological responses associated with temporary suppression of tinnitus induced by low-level laser (LLL) irradiation. Methods: This study was conducted on 20 subjects with subjective tinnitus. All subjects signed the informed consent form and satisfied all the study eligibility criteria...
2017: Journal of Lasers in Medical Sciences
https://www.readbyqxmd.com/read/29066019/assessment-of-coded-excitation-implementation-for-estimating-heat-induced-speed-of-sound-changes
#19
Oren Gargir, Haim Azhari, Michael Zibulevsky
Speed of sound (SoS) is an acoustic property that is highly sensitive to changes in tissues. SoS can be mapped non-invasively using ultrasonic through transmission wave tomography. This however, practically limits its clinical use to the breast. A pulse-echo-based method that has broader clinical use and that can reliably measure treatment-induced changes in SoS even under poor signal-to-noise ratio (SNR) is highly desirable. The aim of this study was to evaluate the implementation of coded excitations (CoEs) to improve pulse-echo monitoring of heat-induced changes in the SoS...
January 2018: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/29064602/brain-stimulation-induced-neuroplasticity-underlying-therapeutic-response-in-phantom-sounds
#20
Timm B Poeppl, Berthold Langguth, Astrid Lehner, Thomas Frodl, Rainer Rupprecht, Peter M Kreuzer, Michael Landgrebe, Martin Schecklmann
Noninvasive brain stimulation can modify phantom sounds for longer periods by modulating neural activity and putatively inducing regional neuroplastic changes. However, treatment response is limited and there are no good demographic or clinical predictors for treatment outcome. We used state-of-the-art voxel-based morphometry (VBM) to investigate whether transcranial magnetic stimulation-induced neuroplasticity determines therapeutic outcome. Sixty subjects chronically experiencing phantom sounds (i.e., tinnitus) received repetitive transcranial magnetic stimulation (rTMS) of left dorsolateral prefrontal and temporal cortex according to a protocol that has been shown to yield a significantly higher number of treatment responders than sham stimulation and previous stimulation protocols...
January 2018: Human Brain Mapping
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