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Results 451 - 500 of 961
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Rahmatallah S - - 2005
A portable, nuclear magnetic resonance (NMR) probe is described which utilises the intrinsic inhomogeneity of the field produced by a single-sided magnet to provide spatial encoding of the NMR signal. The probe uses a longitudinally magnetized hollow cylinder, and a figure-8 radiofrequency (RF) surface coil. The system has been used ...
Maril Nimrod - - 2005
PURPOSE: To develop a fully automated algorithm for combining multivoxel magnetic resonance spectroscopy (MRS) data acquired with a phased-array coil. MATERIALS AND METHODS: The frequency-domain fitting method of LCModel (Provencher SW, Magn Reson Med 1993;30:672-679) was utilized to analyze the individual data sets. The phase corrections and the metabolite areas ...
Chang Hyun Sung - - 2005
Detecting and classifying edge components in images find a wide range of applications from perceptually improved coding schemes to content-based searches. In this paper, a fast and systematic scheme is proposed to classify the edge orientation of each block in discrete cosine transform (DCT)-compressed images. Derived from a simple, but ...
Kim Jong Min - - 2005
A hydrophobic polymeric tip of atomic force microscopy has been fabricated by two-photon adsorbed photopolymerization methods (TPAP). The fabrication was performed by a layer-by-layer polymerization of sliced multiple three-dimensional computer-aided design data. The used base resin was composed of acrylate and epoxy, which showed hydrophobic properties after the photopolymerization. For ...
Arencibia A - - 2005
The objective of this study was to define the anatomy of the cranioencephalic structures and associated formations in camel using magnetic resonance imaging (MRI). MR images were acquired in sagittal, transverse and oblique dorsal planes, using spin-echo techniques, a magnet of 1.5 T and a standard human body coil. MR ...
Liu Jie J Department of Biomedical Engineering, University of California Davis, Davis, CA, USA. - - 2005
Decorrelation strain noise can be significantly reduced in low echo-signal-to-noise (eSNR) conditions using coded excitation. Large time-bandwidth-product (>30) pulses are transmitted into tissue mimicking phantoms with 2.5-mm diameter inclusions that mimic the elastic properties of breast lesions. We observed a 5-10 dB improvement in eSNR that led to a doubling ...
Berzhanskaya Julia - - 2005
The perception of a glossy surface in a static monochromatic image can occur when a bright highlight is embedded in a compatible context of shading and a bounding contour. Some images naturally give rise to the impression that a surface has a uniform reflectance, characteristic of a shiny object, even ...
Weiger Markus - - 2005
Sensitivity encoding (SENSE) with a receiver coil array is typically used as a means of reducing the scan time in MRI. The speed benefit usually comes at some expense in terms of the signal-to-noise ratio (SNR) efficiency, which has been notorious as the main downside of SENSE and parallel MRI ...
Nakayama Kazuya - - 2005
Many images are generated by medical equipment and the number of images to be stored increases yearly. To cope with the large digital storage and transmission requirements, data compression techniques have been studied. In the present study, grayscale data (2 bytes/pixel) were divided into high bytes and low bytes, and ...
De Zanche Nicola - - 2005
A general analytical framework is presented for the design of birdcage radiofrequency resonators on cylindrical formers having arbitrary cross-sectional shape. The primary objective of such shapes would be to improve the sensitivity of the NMR experiment to noncircular regions of the human anatomy while maintaining field homogeneity and quadrature polarization ...
Rojas R R Centro de Investigación en Imagenología e Instrumentación Médica, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, DF-09340, - - 2005
The electromagnetic properties of a new volume resonator coil for MR neuroimaging are studied. This coil design is based on a resonator coil called PERES coil. A commercial software tool based on the finite-element method is used to compute the electric and magnetic fields for the quasi- static regime for ...
Khare Ashish A Dept. of Electron. & Commun., Allahabad - - 2005
Deblurring in the presence of non-Gaussian noise is a hard problem, specially in ultrasonic and CT images. In this paper, a new method of image restoration, using complex wavelet transform, has been devised and applied to deblur in the presence of high speckle noise. It has been shown that the ...
Yee Lau Phooi P Student Member, IEEE, Department of Information and Computer Science, Keio University, Yokohama 223-8522, Japan (e-mail: - - 2005
The objective of this paper is to present a secure distribution method to distribute healthcare records (e.g. video streams and digitized image scans). The availability of prompt and expert medical care can meaningfully improve health care services in understaffed rural and remote areas, sharing of available facilities, and medical records ...
Sandgren Niclas N Systems and Control Division, Department of Information Technology, Uppsala University, P.O. Box 337, SE-751 05 Uppsala Sweden. Email: - - 2005
In several practical magnetic resonance spectroscopy (MRS) applications the user is interested only in the spectral content of a specific frequency band of the spectrum. A frequency-selective (or sub-band) method estimates only the parameters of those spectroscopic components that lie in a pre-selected frequency band of the spectrum in a ...
Huang Feng F Invivo - - 2005
In magnetic resonance imaging (MRI), surface coils have the advantage of higher signal to noise ratio (SNR) but suffer from image inhomogeneity due to the non-uniform sensitivity profile. To remove bright spots caused by non-uniform sensitivity profiles, a gradient weighted smoothing method is discussed in this work. A partial differential ...
Shen S S Dept. of Psychol., Surrey Univ., - - 2005
Artifacts in magnetic resonance images can make conventional intensity-based segmentation methods very difficult, especially for the spatial intensity non-uniformity induced by the radio frequency (RF) coil. The non-uniformity introduces a slow-varying shading artifact across the images. Many advanced techniques, such as nonparametric, multi-channel methods, cannot solve the problem. In this ...
Heckenburg Greg - - 2005
In this paper, we present a new thalamus segmentation method for MRI images based on a new type of deformable model-Lagrangian Surface Flow. Given a MRI image, the user can interactively initialize a seed model within region of interest. The model will then start to grow according to both boundary ...
Gang Wang W School of life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054. - - 2005
The infrastructure to deploy security standards is often lacking during modern telemedicine. As a branch of watermarking technique, the fragile watermarking provides us a good solution to the authentication for telemedicine. A fragile watermarking algorithm based on least significant bit (LSB), hash function and chaotic sequence is presented in this ...
Le Bec Gael G Laboratory of Images and Signals and the Laboratoire d'Electrotechnique de Grenoble, BP 46, 38402 St Martin d'Heres CEDEX, FRANCE (phone: +33-476-82-71-39; fax: +33-476-82- 63-84; e-mail: lebec@ - - 2005
Parallel Magnetic Resonance Imaging (MRI) methods employ receiver coils sensitivities to reduce imaging time: reconstruction algorithms need RF field maps which must be measured or estimated. Assuming statistical independence of different regions in a MR image, we consider the sensitivity estimation as a Blind Source Separation (BSS) problem that can ...
Lee Ray R New York University Medical Center, 660 First Ave. First Floor, New York, NY - - 2005
Hyperpolarized 3He gas MRI has a serious potential for assessing pulmonary functions. Due to the fact that the non-equilibrium of the gas results in a steady depletion of the signal level over the course of the excitations, the signal-tonoise ratio (SNR) can be independent of the number of the data ...
Salvado O O Dept. of Biomedical Engineering, Case Western Reserve University, Cleveland, OH - - 2005
We are involved in a comprehensive program to characterize atherosclerotic disease using multiple MR images having different contrast mechanisms (T1W, T2W, PDW, magnetization transfer, etc.) of human carotid and animal model arteries. We use specially designed intravascular and surface array coils that give high signal-to-noise but suffer from sensitivity inhomogeneity ...
Li Bin B Deptartment of Clinical Engineering, Shanghai Sixth People's Hospital. Shanghai, - - 2005
Due to the MRI signal is much low, the improvement of image quality becomes the important goals for MRI equipment R&D. The RF coil is one of the most important factors in detecting the MRI signal. A new neck coil is developed with four channels phase array design and evaluated. ...
Xu Guizhi G Department of Precision Instrument, Tianjin University, Tianjin 300072, China, Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Heibei University of Technology, Tianjin 300130, China. - - 2005
Transcranial magnetic stimulation (TMS) is a new tool for the study of the human brain and for neurological therapeutics. Magnetic coil design is very important in the TMS technique. Precise spatial localization of stimulation sites is the key of efficient functional magnetic stimulations. This paper develops circular coils, figure-of-8 coils ...
Sarkar Sandip S Microelectronics Division, Saha Institute of Nuclear Physics, Bidhannagar, Kolkata 700064, India. - - 2005
Interpolation is a very important technique in medical image processing. Of the different generations of interpolation kernels, the one using combinations of Gaussians and its partial derivatives, is locally compact, has excellent Fourier properties and is easy to handle analytically. But the dc-constancy behaviour i.e. the sum of the samples ...
Trakic Adnan A The School of Information Technology and Electrical Engineering, The University of Queensland, St. Lucia, - - 2005
We have recently introduced the concept of whole-body asymmetric MRI systems [1]. In this theoretical study, we investigate the PNS characteristics of whole-body asymmetric gradient systems as compared to conventional symmetric systems. Recent experimental evidence [2] supports the hypothesis of transverse gradients being the largest contributor of PNS due to ...
Barbatti M - - 2004
Multireference configuration interaction with singles and doubles (MR-CISD) calculations have been performed for the optimization of conical intersections and stationary points on the ethylene excited-state energy surfaces using recently developed methods for the computation of analytic gradients and nonadiabatic coupling terms. Basis set dependence and the effect of various choices ...
Hoshino Masaru - - 2004
A recently published experiment for the measurement of 1JHN, 1JNC', and 2JHC' coupling constants [J. Am. Chem. Soc. 125 (2003) 11504] was modified to yield a double-TROSY experiment which selects 1 of the 16 multiplet components from a 15N-HSQC spectrum recorded of a uniformly 15N/13C-labelled protein. Subspectra containing any 1 ...
Wilson H F - - 2004
Density functional calculations are performed to identify features observed in STM experiments after phosphine (PH3) dosing of the Si(001) surface. On the basis of a comprehensive survey of possible structures, energetics, and simulated STM images, three prominent STM features are assigned to structures containing surface bound PH2, PH, and P, ...
Cronhjort Andreas - - 2004
An algorithm for segmentation of diesel spray images has been developed. Its most important feature is robustness against experimental setups that fail to guarantee images whose histograms show two distinct peaks. According to the approach presented, only the peak from the background is used, and it is assumed that the ...
Wang H - - 2004
In order to increase the throughput of high-resolution nuclear magnetic resonance spectroscopy a multiple-coil probe, which enables the simultaneous analysis of eight different samples, was designed. The probe, consisting of eight identical solenoidal coils, was constructed for operation at 600 MHz. By using four receivers and radiofrequency switches, spectra from ...
Atkinson David D Division of Imaging Sciences, Guy's Hospital, Kings College London, London SE1 9RT, UK. - - 2004
Multiple MRI receiver coils provide extra information and can enable the reconstruction of multiple images using data from different combinations of coils. Comparison of these images shows that artifacts due to motion or flowing blood appear with different intensities due to the differing coil sensitivities. Typically, the artifact appears amplified ...
Volegov Petr - - 2004
A system that simultaneously measures magnetoencephalography (MEG) and nuclear magnetic resonance (NMR) signals from the human brain was designed and fabricated. A superconducting quantum interference device (SQUID) sensor coupled to a gradiometer pickup coil was used to measure the NMR and MEG signals. 1H NMR spectra with typical Larmor frequencies ...
Nagata Tamaki - - 2004
AIM: To evaluate the image quality of MR angiography (MRA) with a peripheral vascular coil. MATERIALS AND METHODS: A peripheral vascular coil, a technical coil used in MRA of the pelvis and lower extremities, has 12 individual coil elements arranged in six pairs. We evaluated the performance of a peripheral ...
Leiner Tim - - 2004
PURPOSE: To explore the imaging capabilities of a new commercially available, three-station, 129-cm long, 12-element phased array coil for contrast-enhanced magnetic resonance angiography (CE-MRA) in patients with symptomatic peripheral arterial occlusive disease. MATERIALS AND METHODS: Nineteen patients, referred for peripheral CE-MRA, were evaluated using the new three-station coil. For each ...
Ungersma Sharon E - - 2004
The advent of open magnetic resonance imaging (MRI) scanners and dedicated MRI scanners tailored to specific body parts has led to an increasing number of noncylindrical MRI scanner geometries, for which noncylindrical gradients and shims are needed. These new scanner geometries are driving the need for fast, flexible shim design ...
Ohliger Michael A - - 2004
Theoretical arguments and experimental results are presented that characterize the impact of inductive coupling on the performance of parallel MRI reconstructions. A simple model of MR signal and noise reception suggests that the intrinsic amount of spatial information available from a given coil array is unchanged in the presence of ...
Nguyen Uyen D - - 2004
In this paper, we present a numerical model for evaluating tissue heating during magnetic resonance imaging (MRI). Our method, which included a detailed anatomical model of a human head, calculated both the electromagnetic power deposition and the associated temperature elevations during an MRI head examination. Numerical studies were conducted using ...
Lancaster Jack L - - 2004
The emergence of transcranial magnetic stimulation (TMS) as a tool for investigating the brain has been remarkable over the past decade. While many centers are now using TMS, little has been done to automate the delivery of planned TMS stimulation for research and/or clinical use. We report on an image-guided ...
Pereira Philippe L - - 2004
BACKGROUND: The purpose of this study was to evaluate a new stereotactic method for preoperative coil-marking of musculoskeletal tumors with use of interventional magnetic resonance imaging. METHODS: Nine patients with a soft-tissue or bone-marrow tumor were referred to our department for preoperative marking of the extent of the lesion. In ...
Zuehlsdorff Sven - - 2004
In active catheter tracking, small RF coils are attached to the catheter for localization. For interactive catheter steering at vessel branchings, it is necessary to visualize not only a single point near the catheter tip but also the entire shape and orientation of the catheter's distal end. Therefore, a 35-mm-long ...
Du J - - 2004
A novel protocol for three-station MR angiography (MRA) of the lower extremities is described. A time-resolved undersampled projection reconstruction (PR) acquisition was used to image the calf station during a first injection, and non-time-resolved PR acquisitions were used with the bolus-chase technique to image the abdomen and thigh stations during ...
Pilleul Frank - - 2004
RATIONALE AND OBJECTIVES: Despite improvements, spatial resolution and image quality with routine surface coils are too limited when detailed information about the gastrointestinal layers is requested. The objective of our feasibility study was to evaluate the potential of a dedicated endoluminal coil to depict different layers of the colonic wall ...
Macura Katarzyna J - - 2004
The purpose of this study was to demonstrate feasibility of intraurethral magnetic resonance imaging (MRI) for in vivo assessment of the female urethra and to determine the anatomy of the urethra and periurethral attachments as depicted using an endourethral MR coil. Twenty-three continent volunteers were studied with a 14F endourethral ...
Gomez-Hassan Diana M - - 2004
Subtle structural deformities of the cerebral cortex have been shown to be the cause of seizures in patients with refractory epilepsy. Brain imaging using high-resolution focused protocols with standard head coils may not provide sufficient image quality needed for evaluating subtle cortical abnormalities. The authors describe the use of a ...
Han Byung H - - 2004
We introduce some simulation and experiment results of the multichannel magnetic stimulator development that has been carried out as an initial attempt to realize a multichannel functional magnetic stimulator. For efficient functional magnetic stimulations, precise spatial localization of stimulation sites without any movements of the stimulation coils is very important. ...
Talmi Amos - - 2004
Hartmann-Shack wave-front sensors produce a distorted grid of spots whose deviation from perfection is linear with the wave-front gradient. Usually, the centroid of each spot is calculated to provide that deviation, but it is also possible to perform the calculation by Fourier demodulation of the spot pattern [Opt. Commun. 215, ...
Ikeda Takayuki - - 2004
PURPOSE: To compare the performance of the phased-array coil (PAC) with that of the single-loop coil (SLC) in magnetic resonance (MR) imaging of the breast. MATERIALS AND METHODS: MR imaging was performed with a 1.5T MR imager. A phantom study was performed with the right element of the two coils ...
Fukasaku K K Computer and Information Division, Advanced Computing Centre, The Institute of Physical and Chemical Research (RIKEN); Department of Neurosurgery, Kasukabe Chuo General Hospital; Japan - fukasaku@med.nagoya-u.ac.jp - - - 2004
Detached GDC was observed by high resolutional industrial microCT, whose resolution was higher than 0.1 mm. Unexpected destruction of the coils (kinking) was detected and unraveling also clearly visualized. Much higher resolution can improve safe and effectivity of GDC procedure.
Barrera Tony - - 2004
In this paper, we show how spherical linear interpolation can be used to produce shading with a quality at least similar to Phong shading at a computational effort in the inner loop that is close to that of the Gouraud method. We show how to use the Chebyshev's recurrence relation ...
Ludwig R - - 2004
A new apparatus has been developed that integrates an animal restrainer arrangement for small animals with an actively tunable/detunable dual radio-frequency (RF) coil system for in vivo anatomical and functional magnetic resonance imaging of small animals at 4.7 T. The radio-frequency coil features an eight-element microstrip line configuration that, in ...
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