Search Results
Results 401 - 450 of 943
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Meyer Craig H - - 2006
Spiral k-space scanning is a rapid magnetic resonance imaging (MRI) technique that can provide an order of magnitude reduction in scan time compared to conventional spin warp techniques. Parallel imaging is another method for reducing scan time that exploits spatially varying radiofrequency (RF) coil sensitivities to reduce the amount of ...
Bhattarai Nitya - - 2006
The purpose of this study was to describe the features of intraductal papilloma on MR ductography using a microscopic coil. Intraductal papilloma appeared in most cases as a well-circumscribed mass with early enhancement and delayed washout associated with a dilated duct, predominantly showing signal hyperintensity on T1- and T2-weighted imaging.
Zangos Stephan - - 2006
The purpose of this study was to examine the feasibility and safety of MR-guided biopsies with a newly designed cordless coil in an open low-field magnetic resonance (MR) system. Eleven patients were biopsied using a low-field system (0.2 T, Magnetom Concerto, Siemens) by using the new cordless coil (Siemens). The ...
Bianchi Paolo P - - 2005
The development of new surgical techniques and use of neoadjuvant therapy have increased the need for accurate preoperative staging of rectal cancer. We compared the ability of endoscopic ultrasonography (EUS) and two magnetic resonance imaging (MRI) coils to locally stage rectal carcinoma before surgery. Forty-nine patients with histologically proven rectal ...
Mezheritsky Alex V - - 2005
In the absolute-immittance spectrum of a piezoelectric resonator (PR), if the relative resonance-antiresonance frequency interval of a high-intensity resonance is basically determined by the coefficient of electromechanical coupling (CEMC), the relative resonance-antiresonance frequency interval of a low-intensity resonance with the resonance-antiresonance attenuation less than 15 dB, regardless of the reason, ...
Bidinosti C P - - 2005
We provide an exact expression for the magnetic field produced by cylindrical saddle-shaped coils and their ideal shield currents in the low-frequency limit. The stream function associated with the shield surface current is also determined. The results of the analysis are useful for the design of actively shielded radio-frequency (RF) ...
Bellgowan Patrick S F - - 2006
Using gradient-echo EPI, signal dropout due to macroscopic off resonance effects can prevent blood-oxygenation-level-dependent (BOLD) signal change detection. The anterior medial temporal lobe (MTL) is located near these susceptibility gradients and therefore shows considerable signal dropout with GE-EPI. Reducing the volume of the image voxel reduces susceptibility-related signal dropout. However, ...
Salamon Peter - - 2006
A robust algorithm is presented for labeling rows and columns in an irregular array. The algorithm is based on hierarchical pattern matching to a local lattice, which is used as a template. Starting from the best local match, the pattern is expanded hierarchically to encompass the entire array. An application ...
Ramadan Qasem - - 2006
An innovative microfluidic platform for magnetic beads manipulation is introduced, consisting of novel microfabricated 3D magnetic devices positioned in a microfluidic chamber. Each magnetic device comprises of an embedded actuation micro-coil in various design versions, a ferromagnetic pillar, a magnetic backside plate and a sensing micro-coil. The various designs of ...
Gray Robert W - - 2005
Reductions in MRI-induced heating at 1.5 T resulting from a simple design change to coiled wires were investigated. MRI-induced heating was assessed for two different coiled wire forms (length, 26 cm): (1) multi-filar coiled wire form and (2) multi-filar coiled wire form having a different coiled pitch, providing an air ...
Busch Martin - - 2005
Stents that have been implanted to preserve the results of vascular dilatation are frequently affected by in-stent restenosis, which ideally should be followed up by a noninvasive diagnostic modality. Active MRI stents can enable this kind of follow-up, while normal metallic stents can not. The prototype stents investigated in this ...
Baker Kenneth B - - 2005
OBJECTIVE: To evaluate the ability of a lead management device to reduce magnetic resonance imaging (MRI)-related heating of deep brain stimulation (DBS) leads and thereby to decrease the risks of exposing patients with these implants to MRI procedures. METHODS: Experiments were performed using the Activa series (Medtronic, Inc., Minneapolis, MN) ...
Hartnett John G - - 2005
Method of Lines and Finite Element Analysis investigations have been performed to optimize parameters in a TE011 mode cavity resonator suitable for a spaceborne hydrogen maser. We report on designs that were explored to find a global maximum in the important design parameters for the microwave cavity used in a ...
Deka K - - 2006
A new centric scan imaging methodology for density profiling of materials with short transverse relaxation times is presented. This method is shown to be more robust than our previously reported centric scan pure phase encode methodologies. The method is particularly well suited to density imaging of low gyro-magnetic ratio non-proton ...
Nývlt M - - 2005
Magnetization-induced optical surface second harmonic generation (SHG) in the longitudinal geometry was used to study magnetism on the p(1 x 1)O/Fe(001) surface during a layer-by-layer Fe growth with surfactant oxygen. Considerable one-monolayer oscillations were observed. Minima of the magnetization-induced contributions to the second order dielectric susceptibility were detected at half-filled ...
Bouma Henri - - 2005
Conventional edge-detection methods suffer from the dislocation of curved surfaces due to the PSF. We propose a new method that uses the isophote curvature to circumvent this. It is accurate for objects with locally constant curvature, even for small objects (like blood vessels) and in the presence of noise.
Ervin Eric Nathan - - 2005
Alternating current impedance imaging of a 6-microm thick membrane containing conical-shaped pores (60-nm and 2.5-microm diameter openings) using scanning electrochemical microscopy (SECM) is described. Impedance images of the pore openings were obtained by rastering a glass-sealed conically shaped Pt tip (approximately 1-microm radius) above the membrane surface, while measuring the ...
Matsuoka Hiroyoshi - - 2005
Magnetic resonance imaging (MRI) findings in three patients with primary anorectal malignant melanoma are described. Two patients had melanotic and one had amelanotic anorectal melanoma. The findings of MRI with a pelvic coil and an endorectal coil were consistent with pathologic findings. MRI with a pelvic coil demonstrated the melanotic ...
Ohkita Masaki - - 2005
LB films of rigid-rod-like poly(n-hexyl isocyanate) (PHIC), flexible poly(vinyl acetate) (PVAc), and binary mixtures of PHIC as well as of PHIC and PVAc transferred on a mica surface from the air-water interface were observed by AFM. The grain structure of three individual PHIC samples in the AFM images changed shape ...
Sandgren Niclas - - 2005
The use of phased-array receive coils is a well-known technique to improve the image quality in magnetic resonance imaging studies of, e.g., the human brain. It is common to incorporate proton (1H) magnetic resonance spectroscopy (MRS) experiments in these studies to quantify key metabolites in a region of interest. Detecting ...
Yeh Ernest N - - 2005
The use of self-calibrating techniques in parallel magnetic resonance imaging eliminates the need for coil sensitivity calibration scans and avoids potential mismatches between calibration scans and subsequent accelerated acquisitions (e.g., as a result of patient motion). Most examples of self-calibrating Cartesian parallel imaging techniques have required the use of modified ...
Takagi Yukinori - - 2005
PURPOSE: To establish a fast and high-resolution MR sialographic technique that provides fast and high-resolution imaging. MATERIALS AND METHODS: MR sialography was performed on a 1.5-T MR imager using a small (47-mm) surface coil. We determined appropriate sequence parameters, and then applied the technique to the salivary glands of 143 ...
Lu Zhe-Ming - - 2005
The rapid growth of digital multimedia and Internet technologies has made copyright protection, copy protection, and integrity verification three important issues in the digital world. To solve these problems, the digital watermarking technique has been presented and widely researched. Traditional watermarking algorithms are mostly based on discrete transform domains, such ...
Zhan Hua - - 2005
We have constructed a simple container, consisting of a propylene tube, a High-Efficiency Particulate Aerosol (HEPA) filter and a rubber glove, for transporting small animals to magnetic resonance imaging (MRI) facilities that are located outside a pathogen-free environment. Results of pathogens analysis indicate that the container is able to prevent ...
Zhang Xiaoliang - - 2005
A novel concept based on the use of higher-order harmonic resonances in a transmission-line resonator is introduced for the design of high-frequency RF coils at high and ultrahigh fields, where conventional RF coil designs present difficulties and limitations. To demonstrate this concept, we successfully designed and fabricated a 400-MHz RF ...
Tomov Borislav Gueorguiev - - 2005
A compact medical ultrasound beamformer architecture that uses oversampled 1-bit analog-to-digital (A/D) converters is presented. Sparse sample processing is used, as the echo signal for the image lines is reconstructed in 512 equidistant focal points along the line through its in-phase and quadrature components. That information is sufficient for presenting ...
Kolk Andreas - - 2005
BACKGROUND: Multislice computed tomography (MSCT) has been the modality of choice for postoperative detailed imaging of orbital trauma. Unfortunately, it involves extensive exposition of the lens to radiation, especially when taking multiple readings. Also, it holds beam hardening effects and limited imaging (delineation) of the reconstruction material. Alternative conventional magnetic ...
Scharfetter Hermann - - 2005
Magnetic induction tomography (MIT) is a low-resolution imaging modality which aims at the three-dimensional (3D) reconstruction of the electrical conductivity in objects from alternating magnetic fields. In MIT systems the magnetic field perturbations to be detected are very small when compared to the excitation field (ppm range). The voltage which ...
Ozparlak Levent - - 2005
Magnetic resonance-electrical impedance tomography (MR-EIT) is a conductivity imaging method based on injecting currents into the object. In this study, a new MR-EIT method, whereby currents are induced inside the object by using external coils, is proposed. This new method is called induced current magnetic resonance-electrical impedance tomography. In induced ...
Fallon James B - - 2005
Stochastic resonance describes a phenomenon whereby the addition of "noise" to the input of a nonlinear system can improve sensitivity. "Fully tuneable stochastic resonance" is a particular form of the phenomenon that requires the matching of two time scales: one being that of the subthreshold periodic stimulus of the system ...
Smalls Lola K - - 2005
Gynoid lipodystrophy (cellulite) is the irregular, dimpled skin surface of the thighs, abdomen, and buttocks in 85% of post-adolescent women. The distinctive surface morphology is believed to result when subcutaneous adipose tissue protrudes into the lower reticular dermis, thereby creating irregularities at the surface. The biomechanical properties of epidermal and ...
Chakeres Donald W - - 2005
The purpose of this study was to evaluate the capacity of high-resolution magnetic resonance imaging (MRI) to visualize the normal anatomic features of the human hippocampus in vitro, using high field imaging equipment, parameters, and acquisition times appropriate for imaging human subjects in vivo. This research compared high field, high-resolution ...
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 - - 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 ...
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 ...
Yee Lau Phooi - - 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 ...
Sarkar Sandip - - 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 ...
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 ...
Shen S - - 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 ...
Le Bec Gael - - 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 ...
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 ...
Khare Ashish - - 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 ...
Sandgren Niclas - - 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 ...
Salvado O - - 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 ...
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 ...
Li Bin - - 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. ...
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