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https://www.readbyqxmd.com/read/28812315/metabolite-cycled-steam-and-semi-laser-localization-for-mr-spectroscopy-of-the-human-brain-at-9-4t
#1
Ioannis-Angelos Giapitzakis, Tingting Shao, Nikolai Avdievich, Ralf Mekle, Roland Kreis, Anke Henning
PURPOSE: Metabolite cycling (MC) is an MRS technique for the simultaneous acquisition of water and metabolite spectra that avoids chemical exchange saturation transfer effects and for which water may serve as a reference signal or contain additional information in functional or diffusion studies. Here, MC was developed for human investigations at ultrahigh field. METHODS: MC-STEAM and MC-semi-LASER are introduced at 9.4T with an optimized inversion pulse and elaborate coil setup...
August 15, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28807750/high-resolution-simultaneous-imaging-of-intracranial-and-extracranial-arterial-wall-with-improved-cerebrospinal-fluid-suppression
#2
Lei Zhang, Na Zhang, Jun Wu, Xin Liu, Yiu-Cho Chung
PURPOSE: To develop a technique for three dimensional (3D) high resolution joint imaging of intracranial and extracranial arterial walls with improved cerebrospinal fluid (CSF) suppression and good blood suppression based on T1 weighted sampling perfection with application optimized contrast using different angle evolutions (T1w-SPACE) and to compare this technique (hereafter, iSPACE) with alternating with nutation for tailored excitation (DANTE) prepared SPACE sequence (DANTE-SPACE) for their CSF suppression performance around the mid cerebral arteries (MCA) and blood suppression at carotid arteries...
August 11, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28806996/improved-passive-catheter-tracking-with-positive-contrast-for-cmr-guided-cardiac-catheterization-using-partial-saturation-psat
#3
Mari Nieves Velasco Forte, Kuberan Pushparajah, Tobias Schaeffter, Israel Valverde Perez, Kawal Rhode, Bram Ruijsink, Mazen Alhrishy, Nicholas Byrne, Amedeo Chiribiri, Tevfik Ismail, Tarique Hussain, Reza Razavi, Sébastien Roujol
BACKGROUND: Cardiac catheterization is a common procedure in patients with congenital heart disease (CHD). Although cardiovascular magnetic resonance imaging (CMR) represents a promising alternative approach to fluoroscopy guidance, simultaneous high contrast visualization of catheter, soft tissue and the blood pool remains challenging. In this study, a novel passive tracking technique is proposed for enhanced positive contrast visualization of gadolinium-filled balloon catheters using partial saturation (pSAT) magnetization preparation...
August 15, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/28805731/the-role-of-visual-noise-in-influencing-mental-load-and-fatigue-in-a-steady-state-motion-visual-evoked-potential-based-brain-computer-interface
#4
Jun Xie, Guanghua Xu, Ailing Luo, Min Li, Sicong Zhang, Chengcheng Han, Wenqiang Yan
As a spatial selective attention-based brain-computer interface (BCI) paradigm, steady-state visual evoked potential (SSVEP) BCI has the advantages of high information transfer rate, high tolerance to artifacts, and robust performance across users. However, its benefits come at the cost of mental load and fatigue occurring in the concentration on the visual stimuli. Noise, as a ubiquitous random perturbation with the power of randomness, may be exploited by the human visual system to enhance higher-level brain functions...
August 14, 2017: Sensors
https://www.readbyqxmd.com/read/28805725/signal-to-noise-ratio-enhancement-based-on-empirical-mode-decomposition-in-phase-sensitive-optical-time-domain-reflectometry-systems
#5
Zengguang Qin, Hui Chen, Jun Chang
We propose a novel denoising method based on empirical mode decomposition (EMD) to improve the signal-to-noise ratio (SNR) for vibration sensing in phase-sensitive optical time domain reflectometry (φ-OTDR) systems. Raw Rayleigh backscattering traces are decomposed into a series of intrinsic mode functions (IMFs) and a residual component using an EMD algorithm. High frequency noise is eliminated by removing several IMFs at the position without vibration selected by the Pearson correlation coefficient (PCC)...
August 14, 2017: Sensors
https://www.readbyqxmd.com/read/28804751/ultrasound-imaging-and-segmentation-of-bone-surfaces-a-review
#6
Ilker Hacihaliloglu
Due to its real-time, non-radiation based three-dimensional (3D) imaging capabilities, ultrasound (US) has been incorporated into various orthopedic procedures. However, imaging artifacts, low signal-to-noise ratio (SNR) and bone boundaries appearing several mm in thickness make the analysis of US data difficult. This paper provides a review about the state-of-the-art bone segmentation and enhancement methods developed for two-dimensional (2D) and 3D US data. First, an overview for the appearance of bone surface response in B-mode data is presented...
June 2017: Technology
https://www.readbyqxmd.com/read/28800744/physiological-artifacts-in-scalp-eeg-and-ear-eeg
#7
Simon L Kappel, David Looney, Danilo P Mandic, Preben Kidmose
BACKGROUND: A problem inherent to recording EEG is the interference arising from noise and artifacts. While in a laboratory environment, artifacts and interference can, to a large extent, be avoided or controlled, in real-life scenarios this is a challenge. Ear-EEG is a concept where EEG is acquired from electrodes in the ear. METHODS: We present a characterization of physiological artifacts generated in a controlled environment for nine subjects. The influence of the artifacts was quantified in terms of the signal-to-noise ratio (SNR) deterioration of the auditory steady-state response...
August 11, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28800546/mr-based-respiratory-and-cardiac-motion-correction-for-pet-imaging
#8
Thomas Küstner, Martin Schwartz, Petros Martirosian, Sergios Gatidis, Ferdinand Seith, Christopher Gilliam, Thierry Blu, Hadi Fayad, Dimitris Visvikis, F Schick, B Yang, H Schmidt, N F Schwenzer
PURPOSE: To develop a motion correction for Positron-Emission-Tomography (PET) using simultaneously acquired magnetic-resonance (MR) images within 90 s. METHODS: A 90 s MR acquisition allows the generation of a cardiac and respiratory motion model of the body trunk. Thereafter, further diagnostic MR sequences can be recorded during the PET examination without any limitation. To provide full PET scan time coverage, a sensor fusion approach maps external motion signals (respiratory belt, ECG-derived respiration signal) to a complete surrogate signal on which the retrospective data binning is performed...
August 3, 2017: Medical Image Analysis
https://www.readbyqxmd.com/read/28796615/effects-of-signal-saturation-on-qus-parameter-estimates-based-on-high-frequency-ultrasound-signals-acquired-from-isolated-cancerous-lymph-nodes
#9
Kazuki Tamura, Jonathan Mamou, Alain Coron, Kenji Yoshida, Ernest J Feleppa, Tadashi Yamaguchi
Choosing an appropriate dynamic range for acquiring radio-frequency (RF) data from a high-frequency ultrasound (HFU) system is challenging because signals can vary greatly in amplitude as a result of focusing and attenuation effects. In addition, quantitative ultrasound (QUS) results are altered by saturated data. In this study, the effects of saturation on QUS estimates of effective scatterer diameter (ESD) and effective acoustic concentration (EAC) were quantified using simulated and experimental RF data...
August 7, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28793847/effects-of-electrode-deactivation-on-speech-recognition-in-multichannel-cochlear-implant-recipients
#10
Kara C Schvartz-Leyzac, Teresa A Zwolan, Bryan E Pfingst
OBJECTIVES: The objective of the current study is to evaluate how speech recognition performance is affected by the number of active electrodes that are turned off in multichannel cochlear implants. Several recent studies have demonstrated positive effects of deactivating stimulation sites based on an objective measure in cochlear implant processing strategies. Previous studies using an analysis of variance have shown that, on average, cochlear implant listeners' performance does not improve beyond eight active electrodes...
August 10, 2017: Cochlear Implants International
https://www.readbyqxmd.com/read/28792653/comparing-accuracy-and-reproducibility-of-sequential-and-hadamard-encoded-multidelay-pseudocontinuous-arterial-spin-labeling-for-measuring-cerebral-blood-flow-and-arterial-transit-time-in-healthy-subjects-a-simulation-and-in-vivo-study
#11
Jia Guo, Samantha J Holdsworth, Audrey P Fan, Marc R Lebel, Zungho Zun, Ajit Shankaranarayanan, Greg Zaharchuk
PURPOSE: To compare performance of sequential and Hadamard-encoded pseudocontinuous arterial spin labeling (PCASL). MATERIALS AND METHODS: Monte Carlo simulations and in vivo experiments were performed in 10 healthy subjects. Field strength and sequence: 5-delay sequential (5-del. Seq.), 7-delay Hadamard-encoded (7-del. Had.), and a single-delay (1-del.) PCASL, without and with vascular crushing at 3.0T. The errors and variations of cerebral blood flow (CBF) and arterial transit time (ATT) from simulations and the CBF and ATT estimates and variations in gray matter (GM) with different ATT ranges were compared...
August 9, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28789542/intracavity-faraday-modulation-spectroscopy-infamos-a-tool-for-radical-detection
#12
Michele Gianella, Tomas H P Pinto, Xia Wu, Grant A D Ritchie
We present the intra-cavity Faraday modulation spectroscopy technique, whereby optical feedback cavity-enhanced spectroscopy is coupled with Faraday modulation spectroscopy to greatly enhance the interaction path length of a laser beam with a paramagnetic sample in a magnetic field. We describe a first prototype based upon a cw quantum cascade laser targeting a selection of fundamental rovibrational R-branch transitions of nitric oxide (1890 cm(-1)), consisting of a linear cavity (finesse F=6300) and a water-cooled solenoid...
August 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28783570/speech-reception-with-different-bilateral-directional-processing-schemes-influence-of-binaural-hearing-audiometric-asymmetry-and-acoustic-scenario
#13
Tobias Neher, Kirsten C Wagener, Matthias Latzel
Hearing aid (HA) users can differ markedly in their benefit from directional processing (or beamforming) algorithms. The current study therefore investigated candidacy for different bilateral directional processing schemes. Groups of elderly listeners with symmetric (N = 20) or asymmetric (N = 19) hearing thresholds for frequencies below 2 kHz, a large spread in the binaural intelligibility level difference (BILD), and no difference in age, overall degree of hearing loss, or performance on a measure of selective attention took part...
July 29, 2017: Hearing Research
https://www.readbyqxmd.com/read/28781999/accelerating-electron-tomography-reconstruction-algorithm-icon-with-gpu
#14
Yu Chen, Zihao Wang, Jingrong Zhang, Lun Li, Xiaohua Wan, Fei Sun, Fa Zhang
Electron tomography (ET) plays an important role in studying in situ cell ultrastructure in three-dimensional space. Due to limited tilt angles, ET reconstruction always suffers from the "missing wedge" problem. With a validation procedure, iterative compressed-sensing optimized NUFFT reconstruction (ICON) demonstrates its power in the restoration of validated missing information for low SNR biological ET dataset. However, the huge computational demand has become a major problem for the application of ICON...
2017: Biophysics Reports
https://www.readbyqxmd.com/read/28764441/effects-of-reverberation-background-talker-number-and-compression-release-time-on-signal-to-noise-ratio
#15
Paul Reinhart, Pavel Zahorik, Pamela E Souza
Wide dynamic range compression (WDRC) processing in hearing aids alters the signal-to-noise ratio (SNR) of a speech-in-noise signal. This effect depends on the modulations of the speech and noise, input SNR, and WDRC speed. The purpose of the present experiment was to examine the change in output SNR caused by the interaction between modulation characteristics and WDRC speed. Two modulation manipulations were examined: (1) reverberation and (2) variation in background talker number. Results indicated that fast-acting WDRC altered SNR more than slow-acting WDRC; however, reverberation reduced this difference...
July 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28763477/spatially-localized-phosphorous-metabolism-of-skeletal-muscle-in-duchenne-muscular-dystrophy-patients-24-month-follow-up
#16
M T Hooijmans, N Doorenweerd, C Baligand, J J G M Verschuuren, I Ronen, E H Niks, A G Webb, H E Kan
OBJECTIVES: To assess the changes in phosphodiester (PDE)-levels, detected by 31P magnetic resonance spectroscopy (MRS), over 24-months to determine the potential of PDE as marker for muscle tissue changes in Duchenne Muscular Dystrophy (DMD) patients. METHODS: Spatially resolved phosphorous datasets were acquired in the right lower leg of 18 DMD patients (range: 5-15.4 years) and 12 age-matched healthy controls (range: 5-14 years) at three time-points (baseline, 12-months, and 24-months) using a 7T MR-System (Philips Achieva)...
2017: PloS One
https://www.readbyqxmd.com/read/28761180/iterative-reconstruction-improves-detection-of-in-stent-restenosis-by-high-pitch-dual-source-coronary-ct-angiography
#17
Junjie Yang, Xiaobo Yang, Carlo N De Cecco, Taylor M Duguay, Zhiye Chen, Christian Tesche, U Joseph Schoepf, Yundai Chen
Recent studies demonstrated that sinogram affirmed iterative reconstructions (SAFIRE) can produce higher-resolution images with greater robustness for the reduction of various imaging artefacts. Eighty-five patients were prospectively evaluated and underwent a high-pitch spiral acquisition CT scan. In-stent noise, signal-to-noise ratio(SNR), stent-lumen attenuation increase ratio (SAIR), and subjective image quality score were measured and compared between the SAFIRE and Filter back projection (FBP) reconstructions...
July 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28757679/acoustic-ranging-in-poison-frogs-it-is-not-about-signal-amplitude-alone
#18
Max Ringler, Georgine Szipl, Walter Hödl, Leander Khil, Barbara Kofler, Michael Lonauer, Christina Provin, Eva Ringler
ABSTRACT: Acoustic ranging allows identifying the distance of a sound source and mediates inter-individual spacing and aggression in territorial species. Birds and mammals are known to use more complex cues than only sound pressure level (SPL), which can be influenced by the signaller and signal transmission in non-predictable ways and thus is not reliable by itself. For frogs, only SPL is currently known to mediate inter-individual distances, but we hypothesise that the strong territoriality of Dendrobatids could make the use of complex cues for ranging highly beneficial for this family...
2017: Behavioral Ecology and Sociobiology
https://www.readbyqxmd.com/read/28757110/quantitative-eeg-findings-and-response-to-treatment-with-antiepileptic-medications-in-children-with-epilepsy
#19
Chen-Sen Ouyang, Ching-Tai Chiang, Rei-Cheng Yang, Rong-Ching Wu, Hui-Chuan Wu, Lung-Chang Lin
BACKGROUND: Epilepsy is a common chronic disorder in pediatric neurology. Nowadays, a variety of antiepileptic drugs (AEDs) are available. A scientific method designed to evaluate the effectiveness of AEDs in the early stage of treatment has not been reported. PURPOSE: In this study, we try to use quantitative EEG (QEEG) analysis as a biomarker to evaluate therapeutic effectiveness. METHODS: 20 epileptic children were enrolled in this study...
July 27, 2017: Brain & Development
https://www.readbyqxmd.com/read/28752556/3d-multi-echo-radial-imaging-of-23-na-3d-merina-for-time-efficient-multi-parameter-tissue-compartment-mapping
#20
Yasmin Blunck, Sonal Josan, Syeda Warda Taqdees, Bradford A Moffat, Roger J Ordidge, Jon O Cleary, Leigh A Johnston
PURPOSE: This work demonstrates a 3D radial multi-echo acquisition scheme for time-efficient sodium ((23) Na) MR-signal acquisition and analysis. Echo reconstructions were used to produce signal-to-noise ratio (SNR)-enhanced (23) Na-images and parameter maps of the biexponential observed transverse relaxation time ( T2*) decay. METHODS: A custom-built sequence for radial multi-echo acquisition was proposed for acquisition of a series of 3D volumetric (23) Na-images...
July 28, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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