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https://www.readbyqxmd.com/read/29777674/an-approach-for-brain-controlled-prostheses-based-on-scene-graph-steady-state-visual-evoked-potentials
#1
Rui Li, Xiaodong Zhang, Hanzhe Li, Liming Zhang, Zhufeng Lu, Jiangcheng Chen
Brain control technology can restore communication between the brain and a prosthesis, and choosing a Brain-Computer Interface (BCI) paradigm to evoke electroencephalogram (EEG) signals is an essential step for developing this technology. In this paper, the Scene Graph paradigm used for controlling prostheses was proposed; this paradigm is based on Steady-State Visual Evoked Potentials (SSVEPs) regarding the Scene Graph of a subject's intention. A mathematic model was built to predict SSVEPs evoked by the proposed paradigm and a sinusoidal stimulation method was used to present the Scene Graph stimulus to elicit SSVEPs from subjects...
May 16, 2018: Brain Research
https://www.readbyqxmd.com/read/29774597/assessment-of-the-generalization-of-learned-image-reconstruction-and-the-potential-for-transfer-learning
#2
Florian Knoll, Kerstin Hammernik, Erich Kobler, Thomas Pock, Michael P Recht, Daniel K Sodickson
PURPOSE: Although deep learning has shown great promise for MR image reconstruction, an open question regarding the success of this approach is the robustness in the case of deviations between training and test data. The goal of this study is to assess the influence of image contrast, SNR, and image content on the generalization of learned image reconstruction, and to demonstrate the potential for transfer learning. METHODS: Reconstructions were trained from undersampled data using data sets with varying SNR, sampling pattern, image contrast, and synthetic data generated from a public image database...
May 17, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29774480/topographical-assessment-of-neurocortical-connectivity-by-using-directed-transfer-function-and-partial-directed-coherence-during-meditation
#3
Laxmi Shaw, Aurobinda Routray
Due to the presence of nonlinearity and volume conduction in electroencephalography (EEG), sometimes it's challenging to find out the actual brain network from neurodynamical alteration. In this paper, two well-known time-frequency brain connectivity measures, namely partial directed coherence (PDC) and directed transfer function (DTF), have been applied to evaluate the performance analysis of EEG signals obtained during meditation. These measures are implemented to the multichannel meditation EEG data to get the directed neural information flow...
May 17, 2018: Cognitive Processing
https://www.readbyqxmd.com/read/29772676/three-dimensional-terahertz-coded-aperture-imaging-based-on-geometric-measures
#4
Shuo Chen, Xiaoqiang Hua, Hongqiang Wang, Chenggao Luo, Yongqiang Cheng, Bin Deng
For synthetic aperture radars, it is difficult to achieve forward-looking and staring imaging with high resolution. Fortunately, terahertz coded-aperture imaging (TCAI), an advanced radar imaging technology, can solve this problem by producing various irradiation patterns with coded apertures. However, three-dimensional (3D) TCAI has two problems, including a heavy computational burden caused by a large-scale reference signal matrix, and poor resolving ability at low signal-to-noise ratios (SNRs). This paper proposes a 3D imaging method based on geometric measures (GMs), which can reduce the computational burden and achieve high-resolution imaging for low SNR targets...
May 16, 2018: Sensors
https://www.readbyqxmd.com/read/29770639/effect-of-cataract-grade-according-to-wide-field-fundus-images-on-measurement-of-macular-thickness-in-cataract-patients
#5
Mingue Kim, Youngsub Eom, Jong Suk Song, Hyo Myung Kim
PURPOSE: To investigate the effects of cataract grade based on wide-field fundus imaging on macular thickness measured by spectral domain optical coherence tomography (SD-OCT) and its signal-to-noise ratio (SNR). METHODS: Two hundred cataract patients (200 eyes) with preoperative measurements by wide-field fundus imaging and macular SD-OCT were enrolled. Cataract severity was graded from 1 to 4 according to the degree of macular obscuring by cataract artifact in fundus photo images...
May 15, 2018: Korean Journal of Ophthalmology: KJO
https://www.readbyqxmd.com/read/29770492/accelerated-3d-grase-imaging-improves-quantitative-multiple-post-labeling-delay-arterial-spin-labeling
#6
Markus Boland, Rüdiger Stirnberg, Eberhard D Pracht, Johanna Kramme, Roberto Viviani, Julia Stingl, Tony Stöcker
PURPOSE: To investigate the impact of accelerated, single-shot 3D-GRASE acquisition on quantitative arterial spin labeling (ASL) with multiple and single post-labeling delay (PLD) in terms of perfusion-weighted SNR per unit scan time (TSNRPW ) and quantification accuracy. METHODS: Five subjects were scanned on a 3T MRI scanner using the pseudo-continuous arterial spin labeling (PCASL) technique with a 3D-GRASE imaging sequence capable of parallel imaging acceleration...
May 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29769079/a-consistency-evaluation-of-signal-to-noise-ratio-in-the-quality-assessment-of-human-brain-magnetic-resonance-images
#7
Shaode Yu, Guangzhe Dai, Zhaoyang Wang, Leida Li, Xinhua Wei, Yaoqin Xie
BACKGROUND: Quality assessment of medical images is highly related to the quality assurance, image interpretation and decision making. As to magnetic resonance (MR) images, signal-to-noise ratio (SNR) is routinely used as a quality indicator, while little knowledge is known of its consistency regarding different observers. METHODS: In total, 192, 88, 76 and 55 brain images are acquired using T2 * , T1 , T2 and contrast-enhanced T1 (T1 C) weighted MR imaging sequences, respectively...
May 16, 2018: BMC Medical Imaging
https://www.readbyqxmd.com/read/29762258/fast-abdominal-contrast-enhanced-imaging-with-high-parallel-imaging-factors-using-a-60-channel-receiver-coil-setup-comparison-with-the-standard-coil-setup
#8
Jakob Weiss, Petros Martirosian, Steffen Wolf, Wilhelm Horger, Jana Taron, Konstantin Nikolaou, Mike Notohamiprodjo, Ahmed E Othman
PURPOSE: The aim of this study was to assess a novel 60-channel receiver body coil (B60) setup for accelerated contrast-enhanced abdominal magnetic resonance imaging (MR) imaging with respect to signal-to-noise ratio (SNR) and image quality using high parallel-imaging technique (PAT) factors in comparison to a standard 30-channel coil setup. METHODS: All imaging data were acquired on a 3 T MR scanner using a novel B60 receiver coil setup in comparison to a standard 30-channel setup serving as reference standard...
May 14, 2018: Investigative Radiology
https://www.readbyqxmd.com/read/29762057/comparison-of-image-quality-and-radiation-exposure-between-conventional-imaging-and-gemstone-spectral-imaging-in-abdominal-ct-examination
#9
Tianqi Fang, Wei Deng, Martin Wai-Ming Law, Liangping Luo, Liyun Zheng, Ying Guo, Hanwei Chen, Bingsheng Huang
OBJECTIVE: To compare patients' image quality and radiation exposure between gemstone spectral imaging (GSI) with rapid kV switching technique and conventional polychromatic imaging performed in abdominal CT examinations. METHODS: Adult patients who were referred to abdominal CT from October 2015 to March 2016 were enrolled. Unenhanced CT with conventional polychromatic imaging mode and tri-phase (arterial/portal/delayed phase) contrast-enhanced scan with GSI mode were performed with different protocols respectively...
May 15, 2018: British Journal of Radiology
https://www.readbyqxmd.com/read/29762055/evaluating-the-effect-of-increased-pitch-iterative-reconstruction-and-dual-source-ct-on-dose-reduction-and-image-quality
#10
Joanna Gariani, Steve P Martin, Diomidis Botsikas, Christoph D Becker, Xavier Montet
OBJECTIVE: to compare radiation dose and image quality of thoraco-abdominal scans obtained with a high-pitch protocol (pitch 3.2) and iterative reconstruction (SAFIRE) in comparison to standard pitch reconstructed with FBP using dual-source CT. METHODS: 114 CT scans (Somatom Definition Flash, Siemens), 39 thoracic scans, 54 thoraco-abdominal scans and 21 abdominal scans were performed. Analysis of three protocols was undertaken; pitch of 1 reconstructed with FBP, pitch of 3...
May 15, 2018: British Journal of Radiology
https://www.readbyqxmd.com/read/29761949/-research-on-coded-excitation-processing-method-for-magneto-acoustic-signal
#11
Shunqi Zhang, Tao Yin, Zhipeng Liu
Detecting and imaging method of biological electrical characteristics based on magneto-acoustic coupling effect gives valuable information of tissue in early tumor diagnosis and bioelectrical current monitoring. Normal exciting and receiving method is to use single pulse. In this method the signal to noise ratio (SNR) is limited, so the imaging quality and imaging speed are low. In this study, we propose a processing method based on coded excitation to improve SNR and shorten the processing time. The processing method using 13 bit Barker coded excitation and 16 bit Golay code excitation are studied by simulation and experiments...
October 1, 2017: Sheng Wu Yi Xue Gong Cheng Xue za Zhi, Journal of Biomedical Engineering, Shengwu Yixue Gongchengxue Zazhi
https://www.readbyqxmd.com/read/29761413/comparison-of-b-0-versus-b-0-and-b-1-field-inhomogeneity-correction-for-glycosaminoglycan-chemical-exchange-saturation-transfer-imaging
#12
Anja Müller-Lutz, Alexandra Ljimani, Julia Stabinska, Moritz Zaiss, Johannes Boos, Hans-Jörg Wittsack, Christoph Schleich
PURPOSE: The study compares glycosaminoglycan chemical exchange saturation transfer (gagCEST) imaging of intervertebral discs corrected for solely B0 inhomogeneities or both B0 and B1 inhomogeneities. METHODS: Lumbar intervertebral discs of 20 volunteers were examined with T2 -weighted and gagCEST imaging. Field inhomogeneity correction was performed with B0 correction only and with correction of both B0 and B1 . GagCEST effects measured by the asymmetric magnetization transfer ratio (MTRasym ) and signal-to-noise ratio (SNR) were compared between both methods...
May 14, 2018: Magma
https://www.readbyqxmd.com/read/29757799/improved-detection-of-vowel-envelope-frequency-following-responses-using-hotelling-s-t2-analysis
#13
Frederique J Vanheusden, Steven L Bell, Michael A Chesnaye, David M Simpson
OBJECTIVES: Objective detection of brainstem responses to natural speech stimuli is an important tool for the evaluation of hearing aid fitting, especially in people who may not be able to respond reliably in behavioral tests. Of particular interest is the envelope frequency following response (eFFR), which refers to the EEG response at the stimulus' fundamental frequency (and its harmonics), and here in particular to the response to natural spoken vowel sounds. This article introduces the frequency-domain Hotelling's T (HT2) method for eFFR detection...
May 11, 2018: Ear and Hearing
https://www.readbyqxmd.com/read/29756553/effects-of-expanding-envelope-fluctuations-on-consonant-perception-in-hearing-impaired-listeners
#14
Alan Wiinberg, Johannes Zaar, Torsten Dau
This study examined the perceptual consequences of three speech enhancement schemes based on multiband nonlinear expansion of temporal envelope fluctuations between 10 and 20 Hz: (a) "idealized" envelope expansion of the speech before the addition of stationary background noise, (b) envelope expansion of the noisy speech, and (c) envelope expansion of only those time-frequency segments of the noisy speech that exhibited signal-to-noise ratios (SNRs) above -10 dB. Linear processing was considered as a reference condition...
January 2018: Trends in Hearing
https://www.readbyqxmd.com/read/29756324/prospective-frequency-correction-using-outer-volume-suppression-localized-navigator-for-mr-spectroscopy-and-spectroscopic-imaging
#15
Chu-Yu Lee, In-Young Choi, Phil Lee
PURPOSE: New frequency correction methods are required to achieve the accurate measurement of frequency drifts in MRS and MRSI. We present a prospective frequency correction method with outer volume suppression (OVS)-based localization and selective water excitation for effective frequency correction with better SNR improvement compared to other techniques. METHODS: An OVS-localized navigator was developed to prospectively correct frequency drifts during MRS and MRSI measurements...
May 13, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29755844/standard-osem-vs-regularized-pet-image-reconstruction-qualitative-and-quantitative-comparison-using-phantom-data-and-various-clinical-radiopharmaceuticals
#16
Judit Lantos, Erik S Mittra, Craig S Levin, Andrei Iagaru
We investigated the block sequential regularized expectation maximization (BSREM) algorithm. ACR phantom measurements with different count statistics and 60 PET/CT research scans from the GE Discovery 600 and 690 scanners were reconstructed using BSREM and the standard-of-care OSEM algorithm. Hot concentration recovery and cold contrast recovery were measured from the phantom data. Two experienced nuclear medicine physicians reviewed the clinical images blindly. Liver SNR liver and SUVmax of the smallest lesion detected in each patient were also measured...
2018: American Journal of Nuclear Medicine and Molecular Imaging
https://www.readbyqxmd.com/read/29755834/sample-complexity-of-the-boolean-multireference-alignment-problem
#17
Emmanuel Abbe, João M Pereira, Amit Singer
The Boolean multireference alignment problem consists in recovering a Boolean signal from multiple shifted and noisy observations. In this paper we obtain an expression for the error exponent of the maximum A posteriori decoder. This expression is used to characterize the number of measurements needed for signal recovery in the low SNR regime, in terms of higher order autocorrelations of the signal. The characterization is explicit for various signal dimensions, such as prime and even dimensions.
June 2017: Proceedings
https://www.readbyqxmd.com/read/29755338/a-review-of-the-pedunculopontine-nucleus-in-parkinson-s-disease
#18
REVIEW
Isobel T French, Kalai A Muthusamy
The pedunculopontine nucleus (PPN) is situated in the upper pons in the dorsolateral portion of the ponto-mesencephalic tegmentum. Its main mass is positioned at the trochlear nucleus level, and is part of the mesenphalic locomotor region (MLR) in the upper brainstem. The human PPN is divided into two subnuclei, the pars compacta (PPNc) and pars dissipatus (PPNd), and constitutes both cholinergic and non-cholinergic neurons with afferent and efferent projections to the cerebral cortex, thalamus, basal ganglia (BG), cerebellum, and spinal cord...
2018: Frontiers in Aging Neuroscience
https://www.readbyqxmd.com/read/29753661/lower-extremity-ct-angiography-at-80-kvp-using-iterative-model-reconstruction
#19
B Liu, S Gao, Z Chang, C Wang, Z Liu, J Zheng
PURPOSE: To evaluate the use of 80 kVp and iterative model reconstruction (IMR) in lower extremity computed tomography angiography (CTA). MATERIALS AND METHODS: Sixty patients were randomly assigned to Group A or Group B (both n=30) to further undergo CTA. Group A received Protocol 1 (P1) with 120 kVp, 180mAs, and 100mL of contrast agent with filtered back-projection (FBP). Group B received Protocol 2 (P2) and Protocol 3 (P3) with 80 kVp, 140mAs and 75mL of contrast agent with hybrid iterative reconstruction (P2) and IMR (P3)...
May 9, 2018: Diagnostic and Interventional Imaging
https://www.readbyqxmd.com/read/29751689/quantitative-analysis-of-nutrient-elements-in-soil-using-single-and-double-pulse-laser-induced-breakdown-spectroscopy
#20
Yong He, Xiaodan Liu, Yangyang Lv, Fei Liu, Jiyu Peng, Tingting Shen, Yun Zhao, Yu Tang, Shaoming Luo
Rapid detection of soil nutrient elements is beneficial to the evaluation of crop yield, and it's of great significance in agricultural production. The aim of this work was to compare the detection ability of single-pulse (SP) and collinear double-pulse (DP) laser-induced breakdown spectroscopy (LIBS) for soil nutrient elements and obtain an accurate and reliable method for rapid detection of soil nutrient elements. 63 soil samples were collected for SP and collinear DP signal acquisition, respectively. Macro-nutrients (K, Ca, Mg) and micro-nutrients (Fe, Mn, Na) were analyzed...
May 11, 2018: Sensors
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