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https://www.readbyqxmd.com/read/27913340/efficient-3d-reconstruction-in-ultrasound-elastography-via-a-sparse-iteration-based-on-markov-random-fields
#1
Atul Ingle, Tomy Varghese, William Sethares
Percutaneous needle-based liver ablation procedures are becoming increasingly common for treatment of small isolated tumors in hepatocellular carcinoma patients who are not candidates for surgery. Rapid three dimensional visualization of liver ablations has potential clinical value because it can enable interventional radiologists to plan and execute needle-based ablation procedures with real time feedback. Ensuring the right volume of tissue is ablated is desirable to avoid recurrence of tumors from residual untreated cancerous cells...
November 29, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/27913315/speech-enhancement-based-on-neural-networks-improves-speech-intelligibility-in-noise-for-cochlear-implant-users
#2
Tobias Goehring, Federico Bolner, Jessica J M Monaghan, Bas van Dijk, Andrzej Zarowski, Stefan Bleeck
Speech understanding in noisy environments is still one of the major challenges for cochlear implant (CI) users in everyday life. We evaluated a speech enhancement algorithm based on neural networks (NNSE) for improving speech intelligibility in noise for CI users. The algorithm decomposes the noisy speech signal into time-frequency units, extracts a set of auditory-inspired features and feeds them to the neural network to produce an estimation of which frequency channels contain more perceptually important information (higher signal-to-noise ratio, SNR)...
November 29, 2016: Hearing Research
https://www.readbyqxmd.com/read/27911950/a-specialized-multi-transmit-head-coil-for-high-resolution-fmri-of-the-human-visual-cortex-at-7t
#3
Shubharthi Sengupta, Alard Roebroeck, Valentin G Kemper, Benedikt A Poser, Jan Zimmermann, Rainer Goebel, Gregor Adriany
PURPOSE: To design, construct and validate radiofrequency (RF) transmit and receive phased array coils for high-resolution visual cortex imaging at 7 Tesla. METHODS: A 4 channel transmit and 16 channel receive array was constructed on a conformal polycarbonate former. Transmit field efficiency and homogeneity were simulated and validated, along with the Specific Absorption Rate, using [Formula: see text] mapping techniques and electromagnetic simulations. Receiver signal-to-noise ratio (SNR), temporal SNR (tSNR) across EPI time series, g-factors for accelerated imaging and noise correlations were evaluated and compared with a commercial 32 channel whole head coil...
2016: PloS One
https://www.readbyqxmd.com/read/27909929/signal-to-noise-ratio-and-dose-to-the-lens-of-the-eye-for-computed-tomography-examination-of-the-brain-using-an-automatic-tube-current-modulation-system
#4
Supawitoo Sookpeng, Chitsanupong Butdee
PURPOSE: The study aimed to evaluate the image quality in terms of signal-to-noise ratio (SNR) and dose to the lens of the eye and the other nearby organs from the CT brain scan using an automatic tube current modulation (ATCM) system with or without CT gantry tilt is needed. METHODS: An anthropomorphic phantom was scanned with different settings including use of different ATCM, fixed tube current time product (mAs) settings and degree angles of gantry tilt. Gafchromic film XR-QA2 was used to measure absorbed dose of the organs...
December 2, 2016: Emergency Radiology
https://www.readbyqxmd.com/read/27908047/assessing-the-perceptual-contributions-of-level-dependent-segments-to-sentence-intelligibility
#5
Tian Guan, Guang-Xing Chu, Yu Tsao, Fei Chen
The present work assessed the contributions of high root-mean-square (RMS) level (H-level, containing primarily vowels) and middle-RMS-level (M-level, with mostly consonants and vowel-consonant transitions) segments to the intelligibility of noise-masked and noise-suppressed sentences. In experiment 1, noise-masked (by speech-spectrum shaped noise and 6-talker babble) Mandarin sentences were edited to preserve only H- or M-level segments, while replacing the non-target segments with silence. In experiment 2, Mandarin sentences were subjected to four commonly-used single-channel noise-suppression algorithms before generating H-level-only and M-level-only noise-suppressed sentences...
November 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27907941/frequency-selective-non-linear-blending-to-improve-image-quality-in-liver-ct
#6
M N Bongers, G Bier, C Kloth, C Schabel, J Fritz, K Nikolaou, M Horger
Purpose: To evaluate the effects of a new frequency selective non-linear blending (NLB) algorithm on the contrast resolution of liver CT with low intravascular concentration of iodine contrast. Materials and Methods: Our local ethics committee approved this retrospective study. The informed consent requirement was waived. CT exams of 25 patients (60 % female, mean age: 65 ± 16 years of age) with late phase CT scans of the liver were included as a model for poor intrahepatic vascular contrast enhancement...
December 2016: RöFo: Fortschritte Auf Dem Gebiete der Röntgenstrahlen und der Nuklearmedizin
https://www.readbyqxmd.com/read/27906377/lock-in-detection-of-photoacoustic-feedback-signal-for-focusing-through-scattering-media-using-wave-front-shaping
#7
Omer Tzang, Rafael Piestun
Wave-front shaping techniques enable focusing and imaging through scattering media. Unfortunately, most approaches require invasive feedback inside or behind the sample, or use of spatial correlations (memory effect) limiting the application to specific types of samples. Recent approaches overcome these limitations by taking advantage of acoustic waves via the photoacoustic (PA) effect or via photon tagging. We present a fully analog signal processing lock-in scheme for PA detection to improve focusing through scattering media and to efficiently extract nonlinear photoacoustic signals towards wave-front optimization...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27903345/-application-of-low-dose-ct-angiography-with-70-kv-in-patients-with-peripheral-arterial-diseases
#8
Y H Duan, G M Lu, J Wu, X C Yang, D D Wu, Z P Cheng, X M Wang
Objective: To assess the image quality, radiation dose and diagnostic efficiency of peripheral arterial CT angiography (CTA) performed at tube voltage of 70 and 120 kV. Methods: Between January 2014 and December 2015, a total of 200 consecutive patients with known or suspected lower extremity arteriosclerosis obliterans (LEASO) underwent CTA.Patients were randomly divided into 2 groups by different scanning protocols.Group A (n=100): 70 kV and 0.8 ml/kg contrast agent, group B (n=100): 120 kV and 100 ml contrast agent...
November 22, 2016: Zhonghua Yi Xue za Zhi [Chinese medical journal]
https://www.readbyqxmd.com/read/27899332/artificial-neural-network-for-suppression-of-banding-artifacts-in-balanced-steady-state-free-precession-mri
#9
Ki Hwan Kim, Sung-Hong Park
The balanced steady-state free precession (bSSFP) MR sequence is frequently used in clinics, but is sensitive to off-resonance effects, which can cause banding artifacts. Often multiple bSSFP datasets are acquired at different phase cycling (PC) angles and then combined in a special way for banding artifact suppression. Many strategies of combining the datasets have been suggested for banding artifact suppression, but there are still limitations in their performance, especially when the number of phase-cycled bSSFP datasets is small...
November 26, 2016: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/27898299/pfg-nmr-and-bayesian-analysis-to-characterise-non-newtonian-fluids
#10
Thomas W Blythe, Andrew J Sederman, E Hugh Stitt, Andrew P E York, Lynn F Gladden
Many industrial flow processes are sensitive to changes in the rheological behaviour of process fluids, and there therefore exists a need for methods that provide online, or inline, rheological characterisation necessary for process control and optimisation over timescales of minutes or less. Nuclear magnetic resonance (NMR) offers a non-invasive technique for this application, without limitation on optical opacity. We present a Bayesian analysis approach using pulsed field gradient (PFG) NMR to enable estimation of the rheological parameters of Herschel-Bulkley fluids in a pipe flow geometry, characterised by a flow behaviour index n, yield stress τ0, and consistency factor k, by analysis of the signal in q-space...
November 10, 2016: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/27897127/effects-of-noise-exposure-on-the-auditory-function-of-ovariectomized-rats-with-estrogen-deficiency
#11
Xujun Hu, Ying Wang, Chi Chuen Lau
OBJECTIVE: The benefits of estrogen for the auditory function of women depend on a number of factors. In this study, we aimed to examine the impact of noise trauma on the auditory function of ovariectomized rats with estrogen deficiency. MATERIALS AND METHODS: Twenty-eight young, female Sprague-Dawley rats were assigned to three groups (OVX+N, OVX-N, Sham+N). Rats in the OVX+N group and the OVX-N group underwent bilateral ovariectomy (OVX); the OVX+N group alone was also exposed to white noise (N) of 115 dB SPL for 8 hours a day over 14 days...
November 28, 2016: Journal of International Advanced Otology
https://www.readbyqxmd.com/read/27896570/quiet-mr-sequences-in-clinical-routine-initial-experience-in-abdominal-imaging
#12
Sebastian Fischer, David M Grodzki, Markus Domschke, Moritz Albrecht, Boris Bodelle, Katrin Eichler, Renate Hammerstingl, Thomas J Vogl, Stephan Zangos
OBJECTIVE: Purpose of our study was to demonstrate the feasibility and limitations of acoustic noise reduction in a standard clinical MRI protocol for abdominal imaging. METHODS: Acoustic noise and image quality were assessed in 17 patients for a standard liver imaging protocol including TSE and GRE sequences and compared to quiet optimizations as described by Heismann et al. Two blinded readers scored artifacts, the delineation of the abdominal organs and level of diagnostic confidence...
November 28, 2016: La Radiologia Medica
https://www.readbyqxmd.com/read/27895990/influence-of-coherence-length-signal-to-noise-ratio-log-transform-and-low-pass-filtering-on-layer-thickness-assessment-with-oct-in-the-retina
#13
Nomdo M Jansonius, Joel Cervantes, Maddipatla Reddikumar, Barry Cense
Optical coherence tomography (OCT) images of the retina are inevitably affected by the finite width of the coherence function and noise. To make low-reflective layers visible, the raw OCT signal is log transformed; to reduce the effect of noise the images can be low-pass filtered. We determined the effects of these operations on layer thickness assessment, as a function of signal-to-noise ratio (SNR), by performing measurements in a phantom eye and modeling. The log transform appeared to be the key factor in a SNR-dependent overestimation of peak widths and a less predictive bias in the widths of low-reflective layers...
November 1, 2016: Biomedical Optics Express
https://www.readbyqxmd.com/read/27891546/ct-image-quality-in-sinogram-affirmed-iterative-reconstruction-phantom-study-is-there-a-point-of-diminishing-returns
#14
Juan C Infante, Yu Liu, Cynthia K Rigsby
BACKGROUND: In our pediatric practice, we have observed qualitatively limited improvement in the image quality of images generated with sinogram affirmed iterative reconstruction (SAFIRE) compared to series generated with filtered back projection (FBP), particularly in cases near or below a CT dose index volume (CTDIvol) of 1-mGy. OBJECTIVE: To determine whether the image quality advantage of SAFIRE remains constant across clinically used CT dose levels in an American College of Radiology (ACR) CT accreditation phantom including the lower dose range used in pediatric imaging...
November 28, 2016: Pediatric Radiology
https://www.readbyqxmd.com/read/27888758/left-atrium-and-pulmonary-vein-imaging-using-sub-millisiviert-cardiac-computed-tomography-impact-on-radiofrequency-catheter-ablation-cumulative-radiation-exposure-and-outcome-in-atrial-fibrillation-patients
#15
Gianluca Pontone, Daniele Andreini, Maria Petulla, Andrea Annoni, Andrea I Guaricci, Ester Innocenti, Eleonora Russo, Marco Guglielmo, Saima Mushtaq, Andrea Baggiano, Virginia Beltrama, Laura Fusini, Chiara Segurini, Edoardo Conte, Alberto Formenti, Gaetano Fassini, Stefania Riva, Claudio Tondo, Piergiuseppe Agostoni, Antonio L Bartorelli, Mauro Pepi
BACKGROUND: The outcome of radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) has improved thanks to left atrium (LA) anatomy reconstruction by cardiac computed tomography (CCT). A new model-based iterative reconstruction algorithm (MBIR) provides image noise reduction achieving effective radiation dose (ED) close to chest X-ray exposure. Aim of this study was comparing RFCA procedural characteristics, AF recurrence and radiation exposure between patients in whom RFCA was guided by CCT image integration with MBIR versus a CCT standard protocol...
November 9, 2016: International Journal of Cardiology
https://www.readbyqxmd.com/read/27882486/vep-analysis-methods-in-children-with-optic-nerve-hypoplasia-relationship-to-visual-acuity-and-optic-disc-diameter
#16
John P Kelly, James O Phillips, Avery H Weiss
PURPOSE: Assessing vision in young children with optic nerve hypoplasia (ONH) is challenging due to multi-directional infantile nystagmus, the range of optic nerve loss, and cognitive delay. This study examined visual evoked potential (VEP) responses and averaging techniques in children with ONH. The assumption is that EEG epochs with inconsistent temporal phase would be associated with nystagmus, signal reduction due to axon loss, and visual inattention. METHODS: A retrospective chart review was performed on 44 children (average age 2...
November 23, 2016: Documenta Ophthalmologica. Advances in Ophthalmology
https://www.readbyqxmd.com/read/27876736/-the-speech-audiometry-using-the-matrix-sentence-test
#17
M Yu Boboshko, E V Zhilinskaya, A Vazhybok, N V Mal'tseva, M Tsokol', B Kol'meier
The matrix sentence test in which the five-word semantically unpredictable sentences presented under the background noise conditions are used as the speech material was designed and validated for many languages. The objective of the present study was to evaluate the Russian version of the matrix sentence test (RuMatrix test) in the listeners of different ages with normal hearing. At the first stage of the study, 35 listeners at the age from 18 to 33 year were examined. The results of the estimation of the training effect dictated the necessity of conducting two training tracks before carrying out the RuMatrix test proper...
2016: Vestnik Otorinolaringologii
https://www.readbyqxmd.com/read/27875232/a-novel-algorithm-for-learning-sparse-spatio-spectral-patterns-for-event-related-potentials
#18
Chaohua Wu, Ke Lin, Wei Wu, Xiaorong Gao
Recent years have witnessed brain-computer interface (BCI) as a promising technology for integrating human intelligence and machine intelligence. Currently, event-related potential (ERP)-based BCI is an important branch of noninvasive electroencephalogram (EEG)-based BCIs. Extracting ERPs from a limited number of trials remains challenging due to their low signal-to-noise ratio (SNR) and low spatial resolution caused by volume conduction. In this paper, we propose a probabilistic model for trial-by-trial concatenated EEG, in which the concatenated ERPs are expressed as a linear combination of a set of discrete sine and cosine bases...
November 17, 2016: IEEE Transactions on Neural Networks and Learning Systems
https://www.readbyqxmd.com/read/27875125/time-frequency-strategies-for-increasing-high-frequency-oscillation-detectability-in-intracerebral-eeg
#19
Nicolas Roehri, Jean-Marc Lina, John C Mosher, Fabrice Bartolomei, Christian-George Benar
BACKGROUND: High-frequency oscillations (HFOs) are considered to be highly representative of brain tissues capable of producing epileptic seizures. The visual review of HFOs on intracerebral electroencephalography is time consuming and tedious, and it can be improved by time-frequency (TF) analysis. The main issue is that the signal is dominated by lower frequencies that mask the HFOs. Our aim was to flatten (i.e., whiten) the frequency spectrum to enhance the fast oscillations while preserving an optimal signal to noise ratio (SNR)...
December 2016: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/27873353/adaptively-optimized-combination-aoc-of-phased-array-mr-spectroscopy-data-in-the-presence-of-correlated-noise-compared-with-noise-decorrelated-or-whitened-methods
#20
Minjie Wu, Liang Fang, Charles E Ray, Anand Kumar, Shaolin Yang
PURPOSE: A method for adaptively optimized combination (AOC) of MR spectroscopic data from a coil array was recently introduced. The superior performance of the AOC method is evident when compared with the methods that assume uncorrelated noise between coil elements. However, it is unclear whether the AOC method represents the most optimal combination in the presence of correlated noise, when compared with the noise-decorrelated or whitened methods that specifically tackle the correlated noise between coil elements...
November 21, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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