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Phantom sound

Valeria Filippou, Charalampos Tsoumpas
PURPOSE: Printing technology, capable of producing three-dimensional (3D) objects, has evolved in recent years and provides potential for developing reproducible and sophisticated physical phantoms. 3D printing technology can help rapidly develop relatively low cost phantoms with appropriate complexities, which are useful in imaging or dosimetry measurements. The need for more realistic phantoms is emerging since imaging systems are now capable of acquiring multimodal and multiparametric data...
June 22, 2018: Medical Physics
Akira Toyomura, Koichi Yokosawa, Atsushi Shimojo, Tetsunoshin Fujii, Shinya Kuriki
BACKGROUND: Locomotion, which is one of the most basic motor functions, is critical for performing various daily-life activities. Despite its essential function, assessment of brain activity during lower-limb movement is still limited because of the constraints of existing brain imaging methods. NEW METHOD: Here, we describe an MR-compatible, cylindrical treadmill device that allows participants to perform stepping movements on an MRI scanner table. The device was constructed from wood and all of the parts were handmade by the authors...
June 17, 2018: Journal of Neuroscience Methods
Anusha Mohan, Dirk De Ridder, Rajith Idiculla, Clisha DSouza, Sven Vanneste
Tinnitus is the perception of a phantom sound characterized behaviorally by a loudness and a distress component. Although a wealth of information is available about the relationship between these behavioral correlates and changes in static functional connectivity, its relationship with dynamic changes in network connectivity is yet unexplored. The aim of the current study is thus to investigate changes in the flexibility and stability of temporal variability in tinnitus and its relation to loudness and distress using continuous resting state EEG...
June 10, 2018: European Journal of Neuroscience
Francesco Pennazio, Giuseppe Battistoni, Maria Giuseppina Bisogni, Niccolò Camarlinghi, Alfredo Ferrari, Veronica Ferrero, Elisa Fiorina, Matteo Morrocchi, Paola R Sala, Giancarlo Sportelli, Richard Wheadon, Piergiorgio Cerello
In-vivo range monitoring techniques are necessary in order to fully take advantage of the high dose gradients deliverable in hadrontherapy treatments. Positron Emission Tomography (PET) scanners can be used to monitor beam-induced activation in tissues and hence measure the range. The INSIDE (Innovative Solutions for In-beam DosimEtry in Hadrontherapy) in-beam PET scanner, installed at the Italian National Center of Oncological Hadrontherapy (CNAO, Pavia, Italy) synchrotron facility, has already been successfully tested in-vivo during a proton therapy treatment...
June 6, 2018: Physics in Medicine and Biology
Derek Allman, Austin Reiter, Muyinatu A Lediju Bell
Interventional applications of photoacoustic imaging typically require visualization of point-like targets, such as the small, circular, cross-sectional tips of needles, catheters, or brachytherapy seeds. When these point-like targets are imaged in the presence of highly echogenic structures, the resulting photoacoustic wave creates a reflection artifact that may appear as a true signal. We propose to use deep learning techniques to identify these types of noise artifacts for removal in experimental photoacoustic data...
June 2018: IEEE Transactions on Medical Imaging
Christopher Montagne, Yi Zhou
The human visual and auditory systems do not encode an entirely overlapped space when static head and body position are maintained. While visual capture of sound source location in the frontal field is known to be immediate and direct, visual influence in the rear auditory space behind the subject remains under-studied. In this study we investigated the influence of presenting frontal LED flashes on the perceived location of a phantom sound source generated using time-delay-based stereophony. Our results show that frontal visual stimuli affected auditory localization in two different ways - (1) auditory responses were laterally shifted (left or right) toward the location of the light stimulus and (2) auditory responses were more often in the frontal field...
2018: Frontiers in Psychology
Da Zhang, Georgeta Mihai, Larry G Barbaras, Olga R Brook, Matthew R Palmer
PURPOSE: Water equivalent diameter (Dw) reflects patient's attenuation and is a sound descriptor of patient size, and is used to determine size specific dose estimator from a CT exam. Calculating Dw from CT localizer radiographs makes it possible to utilize Dw before actual scans, and minimizes truncation errors due to limited to utilize Dw before actual scans, and minimizes truncation errors due to limited reconstructed fields of view. One obstacle preventing the user community from implementing this useful tool is the necessity to calibrate localizer pixel values so as to represent water equivalent attenuation...
May 10, 2018: Medical Physics
Bilal Malik, Robin Terry, James Wiskin, Mark Lenox
PURPOSE: Quantitative Transmission (QT) ultrasound has shown promise as a breast imaging modality. This study characterizes the performance of the latest generation of QT ultrasound scanners: QT Scanner 2000. METHODS: The scanner consists of a 2048-element ultrasound receiver array for transmission imaging and three transceivers for reflection imaging. Custom fabricated phantoms were used to quantify the imaging performance parameters. The specific performance parameters that have been characterized are spatial resolution (as point spread function), linear measurement accuracy, contrast to noise ratio, and image uniformity, in both transmission and reflection imaging modalities...
May 10, 2018: Medical Physics
Chen Bai, Meiling Ji, Ayache Bouakaz, Yujin Zong, Mingxi Wan
For investigating human transcranial ultrasound imaging (TUI) through the temporal bone, an intact human skull is needed. Since it is complex and expensive to obtain one, it requires that experiments are performed without excision or abrasion of the skull. Besides, to mimic blood circulation for the vessel target, cellulose tubes generally fit the vessel simulation with straight linear features. These issues, which limit experimental studies, can be overcome by designing a 3-D-printed skull model with acoustic and dimensional properties that match a real skull and a vessel model with curve and bifurcation...
May 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Kazuyuki Dei, Brett Byram
Previously, we introduced a model-based beamforming algorithm to suppress ultrasound imaging artifacts caused by clutter sources, such as reverberation and off-axis scattering. We refer to this method as aperture domain model image reconstruction (ADMIRE). In this study, we evaluated the algorithm's limitations and ability to suppress off-axis energy using Field II-based simulations, experimental phantoms and in vivo data acquired by a Verasonics ultrasound system with a curvilinear transducer (C5-2). We compared image quality derived from a standard delay-and-sum (DAS) beamformer, DAS with coherence factor (CF) weighting, ADMIRE and ADMIRE plus CF weighting...
April 25, 2018: Ultrasonics
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
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
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
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
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...
April 15, 2018: Neuroscience
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
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...
June 8, 2018: Progress in Neuro-psychopharmacology & Biological Psychiatry
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
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
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
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