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https://www.readbyqxmd.com/read/28644152/incorporating-hypr-de-noising-within-iterative-pet-reconstruction-hypr-osem
#1
Ju-Chieh Kevin Cheng, Julian C Matthews, Vesna Sossi, Jose Anton-Rodriguez, Andre Salomon, Ronald Boellaard
HighlY constrained back-PRojection (HYPR) is a post-processing de-noising technique originally developed for time-resolved Magnetic Resonance Imaging. It has been recently applied to dynamic imaging for Positron Emission Tomography (PET) and shown promising results. In this work, we have developed an iterative reconstruction algorithm (HYPR-OSEM) which improves the signal-to-noise ratio (SNR) in static imaging (i.e. single frame reconstruction) by incorporating HYPR de-noising directly within the ordered subsets expectation maximization (OSEM) algorithm...
June 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28642695/concealed-around-the-ear-eeg-captures-cognitive-processing-in-a-visual-simon-task
#2
Marlene Pacharra, Stefan Debener, Edmund Wascher
In theory, miniaturized systems such as the around-the-ear electrode arrays (cEEGrids) enable mobile monitoring of the electroencephalogram (EEG) in a variety of real life situations without interfering with the natural setting. However, the research benefit of such cEEGrid recordings critically depends on their validity. To investigate whether visual and motor processing are reflected in the cEEGrid-EEG, a direct comparison of EEG that was concurrently recorded with the cEEGrids and with a high-density cap setup was conducted...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28641265/a-new-method-for-neural-spike-alignment-the-centroid-filter
#3
Benjamin Metcalfe, Chris Clarke, Nick Donaldson, John Taylor
Recordings made directly from the nervous system are a key tool in experimental electrophysiology and the development of bioelectronic medicines. Analysis of these recordings involves the identification of signals from individual neurons, a process known as spike sorting. A critical and limiting feature of spike sorting is the need to align individual spikes in time. However, electrophysiological recordings are made in extremely noisy environments that seriously limit the performance of the spike-alignment process...
June 16, 2017: IEEE Transactions on Neural Systems and Rehabilitation Engineering
https://www.readbyqxmd.com/read/28641248/method-for-simulating-dose-reduction-in-digital-breast-tomosynthesis
#4
Lucas R Borges, Igor Guerrero, Predrag R Bakic, Alessandro Foi, Andrew D A Maidment, Marcelo A C Vieira
This work proposes a new method of simulating dose reduction in digital breast tomosynthesis (DBT), starting from a clinical image acquired with a standard radiation dose. It considers both signal-dependent quantum and signal-independent electronic noise. Furthermore, the method accounts for pixel crosstalk, which causes the noise to be frequency-dependent, thus increasing the simulation accuracy. For an objective assessment, simulated and real images were compared in terms of noise standard deviation, signal-to-noise ratio (SNR) and normalized noise power spectrum (NNPS)...
June 15, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28641240/placing-sites-on-the-edge-of-planar-silicon-microelectrodes-enhances-chronic-recording-functionality
#5
Heui Chang Lee, Janak Gaire, Badrinath Roysam, Kevin J Otto
OBJECTIVE: This study aims to identify the impact of using edge sites over center sites on a planar silicon microelectrode array. METHODS: We used custom-designed, silicon-substrate multi-site microelectrode arrays with sites on the center, edge, and tip. We compared their single unit recording capability, noise level, impedance, and histology to identify the differences between each site location. Wide and narrow devices were used to evaluate if the differences are consistent and meets theoretical expectations...
June 15, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28636326/experimental-study-of-the-detection-limit-in-dual-gate-biosensors-using-ultra-thin-silicon-transistors
#6
Ting Wu, Abdullah Alharbi, Kae-Dyi You, Kim Kisslinger, Eric A Stach, Davood Shahrjerdi
Dual-gate field-effect biosensors (bioFETs) with asymmetric gate capacitances were shown to surpass the Nernst limit of 59 mV/pH. However, previous studies have conflicting findings on the effect of the capacitive amplification scheme on the sensor detection limit, which is inversely proportional to the signal-to-noise ratio (SNR). Here, we present a systematic experimental investigation of the SNR using ultra-thin silicon transistors. Our sensors operate at low voltage and feature asymmetric front and back oxide capacitances with asymmetry factors of 1...
June 21, 2017: ACS Nano
https://www.readbyqxmd.com/read/28629954/high-resolution-myelin-water-imaging-incorporating-local-tissue-susceptibility-analysis
#7
Zhe Wu, Hongjian He, Yi Sun, Yiping Du, Jianhui Zhong
Quantitative myelin water imaging (MWI) from signal T2* decay acquired with multiple Gradient-Recalled Echo (mGRE) sequence has been widely used since its first report. A recent study showed that with low resolution data (2mm isotropic voxels), direct application of complex fitting to a three-pool WM model with frequency shift terms could produce more stable parameter estimation for myelin water fraction mapping. MWI maps of higher spatial resolution resulting in more detailed tissue structures and reduced partial volume effects around white matter/gray matter (WM/GM) interface, however, is more desirable...
June 16, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28629154/two-novel-two-stage-direction-of-arrival-estimation-algorithms-for-two-dimensional-mixed-noncircular-and-circular-sources
#8
Heping Shi, Wen Leng, Zhiwei Guan, Tongzhi Jin
This paper addresses the two-dimensional (2D) direction-of-arrival (DOA) estimation problem with two novel methods for mixed noncircular and circular signals. The first proposed method is named the two-stage direction-of-arrival matrix (TSDOAM) method, and the other is called the two-stage rank reduction (TSRARE) method. The proposed methods utilize both the circularity and the direction-of-arrival differences between the noncircular and circular sources to estimate the 2D directions-of-arrival (DOAs). The maximum detectable 2D angle parameters of the TSDOAM and TSRARE methods are twice those of the existing methods...
June 18, 2017: Sensors
https://www.readbyqxmd.com/read/28626964/impact-of-prior-distributions-and-central-tendency-measures-on-bayesian-intravoxel-incoherent-motion-model-fitting
#9
Oscar Gustafsson, Mikael Montelius, Göran Starck, Maria Ljungberg
PURPOSE: Bayesian model fitting has been proposed as a robust alternative for intravoxel incoherent motion (IVIM) model-fitting parameter estimation. However, consensus regarding choice of prior distribution and posterior distribution central tendency measure is needed. The aim of this study was to compare the quality of IVIM parameter estimates produced by different prior distributions and central tendency measures, and to gain knowledge about the effect of these choices. METHODS: Three prior distributions (uniform, reciprocal, and lognormal) and two measures of central tendency (mean and mode) found in the literature were studied using simulations and in vivo data from a tumor mouse model...
June 19, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28623369/looking-beyond-the-imaging-plane-3d-needle-tracking-with-a-linear-array-ultrasound-probe
#10
Wenfeng Xia, Simeon J West, Malcolm C Finlay, Jean-Martial Mari, Sebastien Ourselin, Anna L David, Adrien E Desjardins
Ultrasound is well suited for guiding many minimally invasive procedures, but its use is often precluded by the poor visibility of medical devices. When devices are not visible, they can damage critical structures, with life-threatening complications. Here, we developed the first ultrasound probe that comprises both focused and unfocused transducer elements to provide both 2D B-mode ultrasound imaging and 3D ultrasonic needle tracking. A fibre-optic hydrophone was integrated into a needle to receive Golay-coded transmissions from the probe and these data were processed to obtain tracking images of the needle tip...
June 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28623107/speech-in-noise-perception-in-unilateral-hearing-loss-relation-to-pure-tone-thresholds-and-brainstem-plasticity
#11
Nicolas Vannson, Chris J James, Bernard Fraysse, Boris Lescure, Kuzma Strelnikov, Olivier Deguine, Pascal Barone, Mathieu Marx
We investigated speech recognition in noise in subjects with mild to profound levels of unilateral hearing loss. Thirty-five adults were evaluated using an adaptive signal-to-noise ratio (SNR50) sentence recognition threshold test in three spatial configurations. The results revealed a significant correlation between pure-tone average audiometric thresholds in the poorer ear and SNR thresholds in the two conditions where speech and noise were spatially separated: dichotic - with speech presented to the poorer ear and reverse dichotic - with speech presented to the better ear...
June 13, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/28622894/impact-of-stimulus-related-factors-and-hearing-impairment-on-listening-effort-as-indicated-by-pupil-dilation
#12
Barbara Ohlenforst, Adriana A Zekveld, Thomas Lunner, Dorothea Wendt, Graham Naylor, Yang Wang, Niek J Versfeld, Sophia E Kramer
Previous research has reported effects of masker type and signal-to-noise ratio (SNR) on listening effort, as indicated by the peak pupil dilation (PPD) relative to baseline during speech recognition. At about 50% correct sentence recognition performance, increasing SNRs generally results in declining PPDs, indicating reduced effort. However, the decline in PPD over SNRs has been observed to be less pronounced for hearing-impaired (HI) compared to normal-hearing (NH) listeners. The presence of a competing talker during speech recognition generally resulted in larger PPDs as compared to the presence of a fluctuating or stationary background noise...
May 25, 2017: Hearing Research
https://www.readbyqxmd.com/read/28621041/extraordinarily-stretchable-all-carbon-collaborative-nanoarchitectures-for-epidermal-sensors
#13
Yichen Cai, Jie Shen, Ziyang Dai, Xiaoxian Zang, Qiuchun Dong, Guofeng Guan, Lain-Jong Li, Wei Huang, Xiaochen Dong
Multifunctional microelectronic components featuring large stretchability, high sensitivity, high signal-to-noise ratio (SNR), and broad sensing range have attracted a huge surge of interest with the fast developing epidermal electronic systems. Here, the epidermal sensors based on all-carbon collaborative percolation network are demonstrated, which consist 3D graphene foam and carbon nanotubes (CNTs) obtained by two-step chemical vapor deposition processes. The nanoscaled CNT networks largely enhance the stretchability and SNR of the 3D microarchitectural graphene foams, endowing the strain sensor with a gauge factor as high as 35, a wide reliable sensing range up to 85%, and excellent cyclic stability (>5000 cycles)...
June 16, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28620616/the-impact-of-combining-a-low-tube-voltage-acquisition-with-iterative-reconstruction-on-total-iodine-dose-in-coronary-ct-angiography
#14
Toon Van Cauteren, Gert Van Gompel, Kaoru Tanaka, Douwe E Verdries, Dries Belsack, Koenraad H Nieboer, Inneke Willekens, Paul Evans, Sven Macholl, Guy Verfaillie, Steven Droogmans, Johan de Mey, Nico Buls
OBJECTIVES: To assess the impact of combining low-tube voltage acquisition with iterative reconstruction (IR) techniques on the iodine dose in coronary CTA. METHODS: Three minipigs underwent CCTA to compare a standard of care protocol with two alternative study protocols combining low-tube voltage and low iodine dose with IR. Image quality was evaluated objectively by the CT value, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in the main coronary arteries and aorta and subjectively by expert reading...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28619834/temporal-and-spatial-variances-in-arterial-spin-labeling-are-inversely-related-to-large-artery-blood-velocity
#15
A D Robertson, G Matta, V S Basile, S E Black, C K Macgowan, J A Detre, B J MacIntosh
BACKGROUND AND PURPOSE: The relationship between extracranial large-artery characteristics and arterial spin-labeling MR imaging may influence the quality of arterial spin-labeling-CBF images for older adults with and without vascular pathology. We hypothesized that extracranial arterial blood velocity can explain between-person differences in arterial spin-labeling data systematically across clinical populations. MATERIALS AND METHODS: We performed consecutive pseudocontinuous arterial spin-labeling and phase-contrast MR imaging on 82 individuals (20 - 88 years of age, 50% women), including healthy young adults, healthy older adults, and older adults with cerebral small vessel disease or chronic stroke infarcts...
June 15, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28618817/an-algorithm-to-increase-intelligibility-for-hearing-impaired-listeners-in-the-presence-of-a-competing-talker
#16
Eric W Healy, Masood Delfarah, Jordan L Vasko, Brittney L Carter, DeLiang Wang
Individuals with hearing impairment have particular difficulty perceptually segregating concurrent voices and understanding a talker in the presence of a competing voice. In contrast, individuals with normal hearing perform this task quite well. This listening situation represents a very different problem for both the human and machine listener, when compared to perceiving speech in other types of background noise. A machine learning algorithm is introduced here to address this listening situation. A deep neural network was trained to estimate the ideal ratio mask for a male target talker in the presence of a female competing talker...
June 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28618295/phase-locked-and-non-phase-locked-eeg-responses-to-pinprick-stimulation-before-and-after-experimentally-induced-secondary-hyperalgesia
#17
Emanuel N van den Broeke, Bart de Vries, Julien Lambert, Diana M Torta, André Mouraux
OBJECTIVE: Pinprick-evoked brain potentials (PEPs) have been proposed as a technique to investigate secondary hyperalgesia and central sensitization in humans. However, the signal-to-noise (SNR) of PEPs is low. Here, using time-frequency analysis, we characterize the phase-locked and non-phase-locked EEG responses to pinprick stimulation, before and after secondary hyperalgesia. METHODS: Secondary hyperalgesia was induced using high-frequency electrical stimulation (HFS) of the left/right forearm skin in 16 volunteers...
May 19, 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28616928/-clinical-study-of-rs-epi-dwi-to-improve-imaging-quality-and-assessment-on-intracranial-mass-lesions
#18
Kai Zhang, Chun-Chao Xia, Qiang Yue, Tao Guo, Wan-Lin Peng, Yu-Ming Li, Lei Li, Fei Zhao, Jin Pu, Qi Leng, Zhen-Lin Li
OBJECTIVES: To explore the clinical value of readout-segmented echo planar imaging (Rs-EPI) sequence in the assessment of intracranial mass lesions compared to the standard single-shot EPI (Ss-EPI) sequence. METHODS: We included 21 patients with intracranial mass lesions who underwent both Ss-EPI diffusion weighted imaging (DWI) and Rs-EPI DWI at 3.0T MR scanner with a twenty-channel head-neck coil. The quality of images was assessed by two experienced radiologists independently...
May 2017: Sichuan da Xue Xue Bao. Yi Xue Ban, Journal of Sichuan University. Medical Science Edition
https://www.readbyqxmd.com/read/28614341/1%C3%A2-%C3%A2-ghz-inp-on-chip-monolithic-extended-cavity-colliding-pulse-mode-locked-laser
#19
R Guzmán, C Gordon, L Orbe, G Carpintero
A record low-repetition rate from an on-chip monolithic InP extended cavity colliding-pulse mode-locked laser is experimentally reported. The device, fabricated in generic InP-based active-passive integration technology, makes use of integrated mirrors to enable its use as a building block within a photonic integrated circuit. This structure allows us to generate an electrical frequency comb with mode spacing of 1 GHz, determined by the 40.5 mm long resonator. Passive and hybrid mode-locking regime conditions are experimentally demonstrated...
June 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28613241/detection-performance-improvement-of-distributed-vibration-sensor-based-on-curvelet-denoising-method
#20
Zengguang Qin, Hui Chen, Jun Chang
A curvelet denoising method has been proposed to reduce the time domain noise to improve the detection performance in the distributed fiber vibration sensing system based on phase-sensitive optical time domain reflectometry. The raw Rayleigh backscattering traces are regarded as a gray image and the random noise can be eliminated by the curvelet transform; hence, the amplitude difference induced by the external vibration can be extracted. The detection of a vibration event with 10 m spatial resolution along a 4 km single mode fiber is demonstrated...
June 14, 2017: Sensors
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