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https://www.readbyqxmd.com/read/28722201/susceptibility-induced-distortion-correction-in-hyperpolarized-echo-planar-imaging
#1
Jack J Miller, Angus Z Lau, Damian J Tyler
PURPOSE: Echo planar imaging is an attractive rapid imaging readout that can image hyperpolarized compounds in vivo. By alternating the sign of the phase encoding gradient waveform, spatial offsets arising from uncertain frequency shifts can be determined. We show here that blip-reversed echo planar imaging can also be used to correct for susceptibility and B0 inhomogeneity effects that would otherwise produce image-domain distortion in the heart. METHODS: Previously acquired blip-reversed cardiac 3D-Spectral-Spatial echo planar imaging volumetric timecourses of hyperpolarized [1-(13) C]pyruvate were distortion corrected by a deformation field estimated by reconstructing signal-to-noise ratio (SNR)-weighted progressively subsampled temporally summed images of each metabolite...
July 19, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28719100/deuteration-of-hyperpolarized-%C3%A2-%C3%A2-c-labelled-zymonic-acid-enables-sensitivity-enhanced-dynamic-mri-of-ph
#2
Christian Hundshammer, Stephan Düwel, Simone Köcher, Malte Gersch, Benedikt Feuerecker, Christoph Scheurer, Axel Haase, Steffen J Glaser, Markus Schwaiger, Franz Schilling
Aberrant pH is characteristic of many pathologies such as ischemia, inflammation or cancer. Therefore, a non-invasive and spatially resolved pH determination is valuable for disease diagnosis, characterization of response to treatment and the design of pH-sensitive drug delivery systems. We recently introduced hyperpolarized zymonic acid (ZA) as a novel MRI probe of extracellular pH utilizing dissolution dynamic polarization (DNP) for a more than 10,000-fold NMR signal enhancement. Here we present a strategy to enhance the sensitivity of this approach by deuteration of ZA (ZAd)...
July 18, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28717625/assessment-of-different-fitting-methods-for-in-vivo-bi-component-t2-analysis-of-human-patellar-tendon-in-magnetic-resonance-imaging
#3
Fang Liu, Richard Kijowski
PURPOSE: To investigate the robustness of four fitting methods for bi-component effective spin-spin T2 (T2(*)) relaxation time analysis of human patellar tendon. METHODS: A three-dimensional (3D) cone ultra-short echo-time (UTE) sequence was performed on the knees of ten healthy volunteers at 3.0T. Four fitting methods incorporating either Gaussian or Rician noise distribution were used for voxel-by-voxel bi-component T2(*) analysis of the patellar tendon. The T2(*) for the short relaxing (T(*)*,s ) and long relaxing (T(*)2,l ) water components and the fraction of the short relaxing water component (fs ) were measured, and different fitting methods were compared using Friedman's and Wilcoxon signed rank tests...
January 2017: Muscles, Ligaments and Tendons Journal
https://www.readbyqxmd.com/read/28715339/development-of-a-low-cost-medical-ultrasound-scanner-using-a-monostatic-synthetic-aperture
#4
Thomas L A van den Heuvel, David J Graham, Kristopher J Smith, Chris L de Korte, Jeffrey A Neasham
OBJECTIVE: In this paper, we present the design of low-cost medical ultrasound scanners aimed at the detection of maternal mortality risk factors in developing countries. METHOD: Modern ultrasound scanners typically employ a high element count transducer array with multichannel transmit and receive electronics. To minimize hardware costs, we employ a single piezoelectric element, mechanically swept across the target scene, and a highly cost-engineered single channel acquisition circuit...
July 17, 2017: IEEE Transactions on Biomedical Circuits and Systems
https://www.readbyqxmd.com/read/28714169/reliable-quantification-of-marrow-fat-content-and-unsaturation-level-using-in-vivo-mr-spectroscopy
#5
Kaipin Xu, Sigurdur Sigurdsson, Vilmundur Gudnason, Trisha Hue, Ann Schwartz, Xiaojuan Li
PURPOSE: To develop a novel technique for reliable quantification of bone marrow fat content and composition using in vivo MR spectroscopy (MRS). METHODS: An MRS quantification method combining both advantages of Voigt line shape model and time-domain analysis was developed. The proposed method was tested using computer-simulated data and in vivo data acquired at lumbar vertebral bodies of 23 subjects (age, 83.8 ± 3.7 y; male, n = 13; female, n = 10) from L1 to L4...
July 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28712012/development-of-an-mr-compatible-hand-exoskeleton-that-is-capable-of-providing-interactive-robotic-rehabilitation-during-fmri-imaging
#6
Sangjoon J Kim, Yeongjin Kim, Hyosang Lee, Pouya Ghasemlou, Jung Kim
Following advances in robotic rehabilitation, there have been many efforts to investigate the recovery process and effectiveness of robotic rehabilitation procedures through monitoring the activation status of the brain. This work presents the development of a two degree-of-freedom (DoF) magnetic resonance (MR)-compatible hand device that can perform robotic rehabilitation procedures inside an fMRI scanner. The device is capable of providing real-time monitoring of the joint angle, angular velocity, and joint force produced by the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of four fingers...
July 15, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28711590/improving-the-detection-of-evoked-responses-to-periodic-stimulation-by-using-bivariate-local-spectral-f-test-application-to-eeg-during-photic-stimulation
#7
Leonardo Bonato Felix, Paulo Fábio Rocha, Eduardo Mazoni Andrade Marçal Mendes, Antonio Mauricio Ferreira Leite Miranda de Sá
The spectral local F-test has been applied for detecting evoked responses to rhythmic stimulation that are embedded in the ongoing electroencephalogram (EEG). Based on the sampling distribution of a flat spectrum at the neighbourhood of the stimulation frequency, spectral peaks in an EEG signal that are due to the stimulation may be readily assessed. Nevertheless, the performance of the technique is strongly affected by both the signal-to-noise ratio (SNR) of the responses and the number of data segments used in the estimation...
July 12, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28709029/study-of-sampling-rate-influence-on-neutron-gamma-discrimination-with-stilbene-coupled-to-a-silicon-photomultiplier
#8
Jinglong Zhang, Michael E Moore, Zhonghai Wang, Zhou Rong, Chaowen Yang, Jason P Hayward
Choosing a digitizer with an appropriate sampling rate is often a trade-off between performance and economy. The influence of sampling rates on the neutron-gamma Pulse Shape Discrimination (PSD) with a solid stilbene scintillator coupled to a Silicon Photomultiplier was investigated in this work. Sampling rates from 125MSPS to 2GSPS from a 10-bit digitizer were used to collect detector pulses produced by the interactions of a Cf-252 source. Due to the decreased signal-to-noise ratio (SNR), the PSD performance degraded with reduced sampling rates...
June 23, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28708721/development-of-correction-for-signal-to-noise-ratio-using-a-t2-with-improved-phase-method
#9
Natsuki Ikemitsu, Yuki Kanazawa, Yuki Matsumoto, Toshiaki Sasaki, Hiroaki Hayashi, Mitsuharu Miyoshi, Masafumi Harada
OBJECTIVE: This study aims to improve the signal-to-noise ratio (SNR) of the phase image focusing T2 and to develop an improved phase (iPhase) image acquired high SNR. METHODS: The iPhase images of phantom and brain were acquired with multi-echo spoiled gradient-echo. The phantom component was a gadopentetate dimeglumine (Gd-DTPA) solution made of different concentrations (0.1, 0.5, and 1 wt%) and Gd-DTPA (0.1, 0.5, and 1 wt%) with agar (1.0 wt%). We applied the iPhase image to susceptibility weighed image (SWI) and evaluated SNR of SWI...
July 13, 2017: Journal of Computer Assisted Tomography
https://www.readbyqxmd.com/read/28708180/4d-spatiotemporal-evolution-of-combustion-intermediates-in-turbulent-flames-using-burst-mode-volumetric-laser-induced-fluorescence
#10
Benjamin R Halls, Naibo Jiang, Terrence R Meyer, Sukesh Roy, Mikhail N Slipchenko, James R Gord
High-speed (20 kHz rate), volumetric laser-induced-fluorescence imaging of combustion intermediates such as a formaldehyde (CH<sub>2</sub>O) and polycyclic aromatic hydrocarbon (PAH) species is demonstrated for tracking the four-dimensional (4D) evolution of turbulent flames. The third-harmonic, 355 nm output of a burst-mode Nd:YAG laser with a 130 mJ/pulse is expanded to 30 mm diameter for volume illumination of the base region of a methane-hydrogen jet diffusion flame. Eight simultaneous images from different viewing angles are used to collect the resulting fluorescence signal for reconstruction of 200 time-sequential three-dimensional volumes over 10 ms duration...
July 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28704483/a-anti-jamming-method-for-satellite-navigation-system-based-on-multi-objective-optimization-technique
#11
Rongling Lang, Hong Xiao, Zi Li, Lihong Yu
In this paper, an anti-jamming method, which turns the single objective optimization problem into a multi-objective optimization problem by utilizing 2-norm, is proposed. The proposed jamming suppression method can reduce the wide nulls and wrong nulls problems, which are generated by the common adaptive nulling methods. Therefore a better signal-noise-ratio (SNR) can be achieved, especially when the jammers are close to satellite signals. It can also improve the robustness of the algorithm. The effectiveness of the proposed method is evaluated by simulation and practical outdoor experiments with the GPS L1 band C/A signals...
2017: PloS One
https://www.readbyqxmd.com/read/28703104/high-pitch-dual-source-ct-angiography-without-ecg-gating-for-imaging-the-whole-aorta-intraindividual-comparison-with-standard-pitch-single-source-technique-without-ecg-gating
#12
Carmelinda Manna, Mario Silva, Rocco Cobelli, Sara Poggesi, Cristina Rossi, Nicola Sverzellati
PURPOSE: We aimed to perform intraindividual comparison of computed tomography (CT) parameters, image quality, and radiation exposure between standard CT angiography (CTA) and high-pitch dual source (DS)-CTA, in subjects undergoing serial CTA of thoracoabdominal aorta. METHODS: Eighteen subjects with thoracoabdominal CTA by standard technique and high-pitch DS-CTA technique within 6 months of each other were retrieved for intraindividual comparison of image quality in thoracic and abdominal aorta...
July 2017: Diagnostic and Interventional Radiology: Official Journal of the Turkish Society of Radiology
https://www.readbyqxmd.com/read/28702796/accuracy-of-isolated-check-visual-evoked-potential-technique-for-diagnosing-primary-open-angle-glaucoma
#13
Li Juan Xu, Liang Zhang, Sha Ling Li, Vance Zemon, Gianni Virgili, Yuan Bo Liang
PURPOSE: The aim of this study was to determine the diagnostic accuracy, sensitivity and specificity of isolated-check visual evoked potentials (icVEP) in primary open-angle glaucoma (POAG). METHODS: Ninety POAG patients and sixty-six healthy controls were recruited consecutively. All subjects underwent icVEP and visual field testing. Swept icVEP response functions were obtained by increasing contrast in six stimulus steps, recording the electroencephalogram synchronized to the stimulus display's frame rate and calculating the corresponding signal-to-noise ratio (SNR) of the response at the fundamental frequency to evaluate visual function...
July 12, 2017: Documenta Ophthalmologica. Advances in Ophthalmology
https://www.readbyqxmd.com/read/28702479/image-quality-and-contrast-agent-exposure-in-cardiac-computed-tomography-angiography-prior-to-transcatheter-aortic-valve-implantation-procedures-using-different-acquisition-protocols
#14
Nina P Hofmann, Moritz Schuetz, Raffi Bekeredjian, Sven Pleger, Emanuel Chorianopoulos, Sorin Giusca, Florian André, Gitsios Gitsioudis, Christopher Schlett, Hans-Ulrich Kauczor, Hugo A Katus, Grigorios Korosoglou
BACKGROUND: ECG-gated cardiac computed tomography angiography (CCTA) has found widespread use for prosthesis sizing before transcatheter aortic valve implantation (TAVI). However, still little data exists on the optimal scan-strategy in such patients. We hypothesized that prospectively triggered CCTA can enable the visualization of aortic valve structures and peripheral arteries with lower radiation and contrast agent exposure in patients considered for TAVI compared to retrospectively gated protocols...
2017: European Journal of Radiology Open
https://www.readbyqxmd.com/read/28699211/better-and-faster-velocity-pulsatility-assessment-in-cerebral-white-matter-perforating-arteries-with-7t-quantitative-flow-mri-through-improved-slice-profile-acquisition-scheme-and-postprocessing
#15
Lennart Geurts, Geert Jan Biessels, Peter Luijten, Jaco Zwanenburg
PURPOSE: A previously published cardiac-gated 2D Qflow protocol at 7 T in cerebral perforating arteries was optimized to reduce velocity underestimation and improve temporal resolution. METHODS: First, the signal-to-noise ratio (SNR) gain of the velocity measurement (SNRv ) was tested for two signal averages versus one. Second, the decrease in velocity underestimation with a tilted optimized nonsaturating excitation (TONE) pulse was tested. Third, the decrease in pulsatility index (PI) underestimation through improved temporal resolution was tested...
July 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28698944/petra-msvat-space-and-semac-sequences-for-metal-artefact-reduction-in-dental-mr-imaging
#16
Tim Hilgenfeld, Marcel Prager, Alexander Heil, Franz Sebastian Schwindling, Mathias Nittka, David Grodzki, Peter Rammelsberg, Martin Bendszus, Sabine Heiland
OBJECTIVES: Dental MRI is often impaired by artefacts due to metallic dental materials. Several sequences were developed to reduce susceptibility artefacts. Here, we evaluated a set of sequences for artefact reduction for dental MRI for the first time. METHODS: Artefact volume, signal-to-noise ratio (SNR) and image quality were assessed on a 3-T MRI for pointwise encoding time reduction with radial acquisition (PETRA), multiple-slab acquisition with view angle tilting gradient, based on a sampling perfection with application-optimised contrasts using different flip angle evolution (SPACE) sequence (MSVAT-SPACE), slice-encoding for metal-artefact correction (SEMAC) and compared to a standard SPACE and a standard turbo-spin-echo (TSE) sequence...
July 11, 2017: European Radiology
https://www.readbyqxmd.com/read/28698477/on-transform-domain-communication-systems-under-spectrum-sensing-mismatch-a-deterministic-analysis
#17
Chuanxue Jin, Su Hu, Yixuan Huang, Qu Luo, Dan Huang, Yi Li, Yuan Gao, Shaochi Cheng
Towards the era of mobile Internet and the Internet of Things (IoT), numerous sensors and devices are being introduced and interconnected. To support such an amount of data traffic, traditional wireless communication technologies are facing challenges both in terms of the increasing shortage of spectrum resources and massive multiple access. The transform-domain communication system (TDCS) is considered as an alternative multiple access system, where 5G and mobile IoT are mainly focused. However, previous studies about TDCS are under the assumption that the transceiver has the global spectrum information, without the consideration of spectrum sensing mismatch (SSM)...
July 8, 2017: Sensors
https://www.readbyqxmd.com/read/28691526/non-enhanced-versus-low-dose-contrast-enhanced-renal-magnetic-resonance-angiography-at-7-t-a-feasibility-study
#18
Anja Laader, Karsten Beiderwellen, Oliver Kraff, Stefan Maderwald, Mark E Ladd, Michael Forsting, Lale Umutlu
Background Considering the currently reported association between a repetitive application and cumulative dosage of Gadolinium (Gd)-based contrast agents and Gd-deposition in brain tissue as well as the risk for the advent of nephrogenic systemic fibrosis (NSF), techniques allowing for a dose reduction become an important key aspect aside from non-enhanced magnetic resonance angiography (MRA) techniques. Thus, this study was focused on the reduction and/or complete omission of contrast agent for renal MRA at 7T...
January 1, 2017: Acta Radiologica
https://www.readbyqxmd.com/read/28691219/comparison-of-reduced-field-of-view-diffusion-weighted-imaging-dwi-and-conventional-dwi-techniques-in-the-assessment-of-rectal-carcinoma-at-3-0t-image-quality-and-histological-t-staging
#19
Yang Peng, Zhen Li, Hao Tang, Yanchun Wang, Xuemei Hu, Yaqi Shen, Daoyu Hu
PURPOSE: To compare image quality (IQ) of reduced field-of-view (rFOV) and full FOV (fFOV) diffusion-weighted imaging (DWI) sequences at 3T, with histological T staging of rectal cancer as a reference standard. MATERIALS AND METHODS: In all, 81 patients with rectal cancer received magnetic resonance (MR) scans (3.0T), including both rFOV and fFOV DWI sequences. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were quantitatively evaluated using the paired t-test...
July 10, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28688583/image-improvement-method-for-positron-emission-mammography
#20
Nikolai V Slavine, Stephen J Seiler, Roderick W McColl, Robert E Lenkinski
PURPOSE: To evaluate in clinical use a rapidly converging, efficient iterative deconvolution algorithm (RSEMD) for improving the quantitative accuracy of previously reconstructed breast images by a commercial positron emission mammography (PEM) scanner. MATERIALS AND METHODS: The RSEMD method was tested on imaging data from clinical Naviscan Flex Solo II PEM scanner. This method was applied to anthropomorphic like breast phantom data and patient breast images previously reconstructed with Naviscan software to determine improvements in image resolution, signal to noise ratio (SNR) and contrast to noise ratio (CNR)...
July 2017: Physica Medica: PM
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