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Results 301 - 350 of 952
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Boecker Daniel - - 2008
The analytical performance of surface plasmon resonance imaging with charge coupled device detection can be improved significantly by splitting a macroscopic sensing surface into multiple microscopic neighboring sensing and referencing subareas. It is shown that such a multiple referencing reduces intensity fluctuations across the total sensing area and, therefore, improves ...
Canaple Laurence - - 2008
Zebrafish embryo is a well-established model used in many fields of modern experimental biology. We demonstrate that it provides a promising model platform for exploring fundamental MR aspects that can be used to screen and study active MR molecules before progressing to more complex living systems. Setting up a dedicated ...
Saito Y - - 2008
Tip-enhanced Raman imaging of strained silicon reveals the property of nanoscale stress imposed on the lattice. Our approach relies on the highly localized excitation provided by a metallized tip. Surface sensitive detections in nanoscale are realized by a reflection-mode configuration combined with 442-nm excitation and a silver-coated silicon nitride tip. ...
Zhang Rui - - 2008
It has been a common challenge to operate optical see-through head-mounted displays in well-lit environments due to the low image brightness and contrast compared with the direct view of a real-world scene. This problem is aggravated in the design of a see-through head-mounted projection display (HMPD) in which the projected ...
Lowery Thomas J - - 2008
Nanoparticle based magnetic relaxation switch (MRSw) biosensors offer the opportunity to develop magnetic resonance based in vitro diagnostics. Critical attributes for point of care in vitro diagnostic products include simple instrumentation and ease of use. To this end, high-resolution biexponential analysis was used to permit measurement and assignment of two ...
Georgouli Theodora - - 2008
OBJECTIVE: High-resolution MRI (HR-MRI) is a powerful non-invasive tool that provides images of higher spatial resolution and enables visualization of tissues previously unidentified with conventional techniques. The utilization of HR-MRI in the eye and orbit is essential due to the minute structure with great tissue diversity. The purpose of this ...
Yao Weijun - - 2008
A 700-mm bore superconducting magnet was built and operated in our laboratory to demonstrate the feasibility of newly developed MgB(2) superconductor wire for fabricating MRI magnets. The magnet, an assembly of 10 coils each wound with a reacted and s-glass insulated wire ~1-km long, was immersed in solid nitrogen rather ...
Li Bing Keong BK The University of Queensland, School of Information Technology and Electrical Engineering, Australia. - - 2008
In this work, a new method has been proposed to accelerate the PROPELLER MRI operation. The proposed method uses a rotary phased array coil and a new method in acquiring the k-space strips and preparing the complete k-space trajectories data set. It is numerically shown that for a 12 strips ...
Brown Ryan R Department of Radiology, Weill Medical College of Cornell University, New York, NY 10022, USA. - - 2008
Noise correlation is an important topic in radiofrequency (RF) coil design for magnetic resonance imaging (MRI). The original noise correlation formula derived by Redpath showed correlation depends on the real part of the inverse impedance matrix. In this work, we introduce a more generalized formula to include effects from transmission ...
Weber Ewald E University of Queensland, School of Information Technology and Electrical Engineering, Australia. - - 2008
In this work, a dedicated, 9.4T shielded 8-element transceive volume-array for large rat MRI applications is designed and the prototype constructed. Angularly oriented radiating structured coil elements are used. It is shown that by orienting the radiating conductors of the coil element angularly, the RF penetration depth can be increased ...
Fischer Gregory S GS Center for Computer Integrated Surgery, Johns Hopkins University, USA. - - 2008
This paper reports an experimental evaluation of the following three different MRI-compatible actuators: a Shinsei ultrasonic motor a Nanomotion ultrasonic motor and a pneumatic cylinder actuator. We report the results of a study comparing the effect of these actuators on the signal to noise ratio (SNR) of MRJ images under ...
White Philip M - - 2008
INTRODUCTION: Endovascular coiling of intracranial aneurysms carries a risk of complications. Early detection and management of complications can improve clinical outcomes. AngioCT is a new imaging technology enabling CT-like images to be generated on a flat-panel digital subtraction angiography system, which can provide immediate "on angio table" identification and thorough ...
Jaramillo Diego - - 2008
The purpose of this general review is to suggest practical strategies to optimize musculoskeletal MR imaging in children. The changes related to ossification and marrow transformation affect the MRI appearance during development. This review summarizes the normal appearance of the growing skeleton on various pulse sequences, as well as ways ...
Brisman J L - - 2008
BACKGROUND AND PURPOSE: Endovascular coil embolization is used increasingly to treat cerebral aneurysms. The purpose of our study was to quantify the incidence of CT-detectable abnormalities after aneurysm coiling and map the radiographic and clinical progression. MATERIALS AND METHODS: We reviewed the radiographic and clinical sequelae of 30 consecutive patients ...
Shidahara Miho - - 2008
PURPOSE: We evaluated the noise reduction capability of wavelet denoising for estimated binding potential (BP) images (k (3)/k (4)) of the peripheral benzodiazepine receptor using (18)F-FEDAA1106 and nonlinear least-square fitting. METHODS: Wavelet denoising within a three-dimensional discrete dual-tree complex wavelet transform was applied to simulate data and clinical dynamic positron ...
Haywood B - - 2007
Results are presented for a model three-axis gradient coil incorporating active acoustic control which is applied to the switched read gradient during a single-shot rapid echo-planar imaging (EPI) sequence at a field strength of 3.0 T. The total imaging acquisition time was 10.6 ms. Substantial noise reduction is achieved both ...
Hyodo F - - 2008
Time-domain (TD) electron paramagnetic resonance (EPR) imaging at 300MHz for in vivo applications requires resonators with recovery times less than 1 micros after pulsed excitation to reliably capture the rapidly decaying free induction decay (FID). In this study, we tested the suitability of the Litz foil coil resonator (LCR), commonly ...
Yoon Jai-Woong - - 2007
The stationary grid commonly used with a digital x-ray detector causes a moiré interference pattern due to the inadequate sampling of the grid shadows by the detector pixels. There are limitations with the previous methods used to remove the moiré such as imperfect electromagnetic interference shielding and the loss of ...
Smith Holly - - 2007
A Helmholtz resonator consists of a hollow neck attached to an empty chamber. This resonator can be modeled as a spring-mass system in which the air moving inside the neck acts as the mass and the gas inside the chamber acts as the spring. Every Helmholtz resonator has a characteristic ...
Boyes Richard G RG Dementia Research Centre, Institute of Neurology, Box 16, University College London, Queen Square, London, UK. - - 2008
Measures of structural brain change based on longitudinal MR imaging are increasingly important but can be degraded by intensity non-uniformity. This non-uniformity can be more pronounced at higher field strengths, or when using multichannel receiver coils. We assessed the ability of the non-parametric non-uniform intensity normalization (N3) technique to correct ...
Seierstad T - - 2007
During the last two decades, there has been an explosive increase in the number of MR investigations involving genetically manipulated mice and rats. Many of the animal studies are performed in a more or less clinical environment, where whole-body MR scanners are the only option available. The quality and acquisition ...
Rondeau Xavier - - 2007
In ground-based astronomy, the inverse problem of phase retrieval from speckle images is a means to calibrate static aberrations for correction by active optics. It can also be used to sense turbulent wavefronts. However, the number of local minima drastically increases with the turbulence strength, mainly because of phase wrapping ...
Lin Fa-Hsuan - - 2007
Multiple receivers can be utilized to enhance the spatiotemporal resolution of MRI by employing the parallel imaging technique. Previously, we have reported the L-curve Tikhonov regularization technique to mitigate noise amplification resulting from the geometrical correlations between channels in a coil array. Nevertheless, one major disadvantage of regularized image reconstruction ...
Awate Suyash P - - 2007
This paper presents a novel method for Bayesian denoising of magnetic resonance (MR) images that bootstraps itself by inferring the prior, i.e., the uncorrupted-image statistics, from the corrupted input data and the knowledge of the Rician noise model. The proposed method relies on principles from empirical Bayes (EB) estimation. It ...
Linn Jennifer - - 2007
Increasing numbers of small animal models are in use in the field of neuroscience research. Magnetic resonance imaging (MRI) provides an excellent method for non-invasive imaging of the brain. Using three-dimensional (3D) MR sequences allows lesion volumetry, e.g. for the quantification of tumor size. Specialized small-bore animal MRI scanners are ...
Ginefri Jean-Christophe - - 2007
Signal-to-noise ratio improvement is of major importance to achieve microscopic spatial resolution in magnetic resonance experiments. Magnetic resonance imaging of small animals is particularly concerned since it typically requires voxels of less than (100 microm)(3) to observe the small anatomical structures having size reduction by a factor of more than ...
Donmez Fuldem Yildirim - - 2008
PURPOSE: To assess the accuracy of magnetic resonance imaging with pelvic phased-array and endorectal coils prospectively, and evaluate if endorectal coil provides any additional information to high resolution pelvic MR imaging in rectal carcinoma staging. MATERIALS AND METHODS: Preoperative MRI of 25 patients with rectal carcinoma was performed with pelvic ...
Castillo-Rubio Carlos F - - 2007
Spatially variant apodization (SVA) is a nonlinear sidelobe reduction technique that improves sidelobe level and preserves resolution at the same time. This method implements a bidimensional finite impulse response filter with adaptive taps depending on image information. Some papers that have been previously published analyze SVA at the Nyquist rate ...
Sosnovik David E - - 2007
PURPOSE: To evaluate the use of a transmit-receive surface (TRS) coil and a cardiac-tailored intensity-correction algorithm for cardiac MRI in mice at 9.4 Tesla (9.4T). MATERIALS AND METHODS: Fast low-angle shot (FLASH) cines, with and without delays alternating with nutations for tailored excitation (DANTE) tagging, were acquired in 13 mice. ...
Vernickel P - - 2007
Multichannel transmit magnetic resonance imaging (MR) systems have the potential to compensate for signal-intensity variations occurring at higher field strengths due to wave propagation effects in tissue. Methods such as RF shimming and local excitation in combination with parallel transmission can be applied to compensate for these effects. Moreover, parallel ...
Huang Tiffany T Y - - 2007
OBJECTIVES: The aim of this study was to characterise the mineral density (MD) of natural enamel white spot lesions (WSLs) using X-ray micro-tomography calibrated with different density hydroxyapatite phantoms. METHODS: Seven natural WSLs from four extracted non-carious premolar teeth were scanned at a voxel size of 7.6 microm using a ...
Settecase Fabio F Department of Medical Imaging and Institute of Medical Science, University of Toronto, Toronto, Ontario, - - 2007
Current applied to wire coils wound at the tip of an endovascular catheter can be used to remotely steer a catheter under magnetic resonance imaging guidance. In this study, we derive and validate an equation that characterizes the relationship between deflection and a number of physical factors: theta/sin(gamma-theta) = nIABL/EI(A) ...
Thomas P C - - 2007
Hyperion is Saturn's largest known irregularly shaped satellite and the only moon observed to undergo chaotic rotation. Previous work has identified Hyperion's surface as distinct from other small icy objects but left the causes unsettled. Here we report high-resolution images that reveal a unique sponge-like appearance at scales of a ...
Hancu Ileana - - 2007
(13)C imaging and spectroscopy in the presence of injected labeled compounds can vastly extend the capability of MRI to perform metabolic imaging. The details of imaging in the presence of injected compounds, however, pose new technological challenges. Pulse sequences, in general, rely on precise flip-angle (FA) calibration to create high ...
Osorio Joseph A - - 2007
PURPOSE: To implement proton magnetic resonance spectroscopic imaging (1H MRSI) at 3 Tesla (3T) using an eight-channel phased-array head coil in a population of brain-tumor patients. MATERIALS AND METHODS: A total of 49 MRI/MRSI examinations were performed on seven volunteers and 34 patients on a 3T GE Signa EXCITE scanner ...
Katscher Ulrich - - 2007
Parallel MRI started with the introduction of coil arrays in improving radiofrequency (RF) acquisition (what is called parallel imaging) and continued with an analogous development for RF transmission (parallel transmission). Based on differences in the spatial sensitivity distributions of the involved array elements, both techniques try to shorten the respective ...
Purkayastha S - - 2007
OBJECTIVE: Circumferential margin involvement (CMI) is an important prognostic indicator for patients with rectal cancer. This meta-analysis aims at evaluating the diagnostic precision of magnetic resonance imaging (MRI) for the preoperative evaluation of CMI in patients with rectal cancer. METHOD: Quantitative meta-analysis was performed comparing MRI against histology after total ...
Carmichael David W DW Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, London, UK. - - 2007
We investigated safety issues and potential experimental confounds when performing functional magnetic resonance imaging (fMRI) investigations in human subjects with fully implanted, active, deep brain stimulation (DBS) systems. Measurements of temperature and induced voltage were performed in an in vitro arrangement simulating bilateral DBS during magnetic resonance imaging (MRI) using ...
Ouhlous Mohamed - - 2007
PURPOSE: To evaluate the ability of a custom-built coil design to provide improved signal-to-noise ratio (SNR) and less signal drop with increasing depth at the carotid artery. MATERIALS AND METHODS: Phased-array surface coils can provide a high SNR to image the carotid vessel wall. However, given the required field-of-view (FOV) ...
Rosen Yael - - 2007
Most prostate MRI/MRS examinations are performed with an endorectal coil inflated with air, leading to an air-tissue interface that induces magnetic susceptibility gradients within the gland. Inflation of the coil with a barium sulfate suspension is described and compared to inflation with air or liquid perfluorocarbon (PFC). The B(0) field ...
Popovici Irina - - 2007
We present a method of locating edges in JPEG-coded images which operates in frequency space on the DCT coefficients. Applied to the quantized DCT coefficients of a block containing a straight edge, the method yields an equation for the edge in a fraction of the operations needed to dequantize and ...
Gufler Hubert - - 2007
The objective of this article is to evaluate the diagnostic accuracy of high-resolution MRI using a microscopy surface coil to stage basal cell carcinomas of the face. High-resolution MRI using a microscopy surface coil is a promising method to determine the extension of basaliomas of the facial region and to ...
Meadowcroft Mark D MD Center for NMR Research, Department of Radiology, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, - - 2007
Direct imaging of a histological slice is challenging. The vast difference in dimension between planar size and the thickness of histology slices would require an RF coil to produce a uniform RF magnetic (B1) field in a 2D plane with minimal thickness. In this work a novel RF coil designed ...
Gupta Rashi - - 2007
The DNA microarray technique allows monitoring the expression levels of thousands of genes simultaneously. A single DNA microarray experiment involves a number of error-prone manual and automated processes, which influence the results and have an impact on the subsequent stages of analysis. Typical problems of arrays are pinning errors while ...
Ségonne Florent - - 2007
In this paper, we focus on the retrospective topology correction of surfaces. We propose a technique to accurately correct the spherical topology of cortical surfaces. Specifically, we construct a mapping from the original surface onto the sphere to detect topological defects as minimal nonhomeomorphic regions. The topology of each defect ...
Avdievich N I NI Department of Radiology, Albert Einstein College of Medicine, Bronx, NY, USA. - - 2007
Typically 31P in vivo magnetic resonance spectroscopic studies are limited by SNR considerations. Although phased arrays can improve the SNR; to date 31P phased arrays for high-field systems have not been combined with 31P volume transmit coils. Additionally, to provide anatomical reference for the 31P studies, without removal of the ...
Georgouli T - - 2008
The eye is involved in several pathologies where precise identification of the underlying condition is essential for the optimal patient care. This preliminary report presents the potential of high-resolution microscopy coil magnetic resonance imaging (HR-MRI) to undertake this task being actively used in the clinical setting. We used a commercially ...
Parvin Bahram - - 2007
Saliency is an important perceptual cue that occurs at different levels of resolution. Important attributes of saliency are symmetry, continuity, and closure. Detection of these attributes is often hindered by noise, variation in scale, and incomplete information. This paper introduces the iterative voting method, which uses oriented kernels for inferring ...
Bentley Michael D - - 2007
The three-dimensional architecture of nephrons in situ and their interrelationship with other nephrons are difficult to visualize by microscopic methods. The present study uses microcomputed X-ray tomography (micro-CT) to visualize intact nephrons in situ. Rat kidneys were perfusion-fixed with buffered formalin and their vasculature was subsequently perfused with radiopaque silicone. ...
Zama Uyrá - - 2007
The sperm of Microstigmus arlei and Microstigmus nigrophthalmus are twisted in a spiral and consist of two regions: the head, formed by an acrosome and a nucleus, and the flagellum, formed by two asymmetric mitochondrial derivatives, a long centriolar adjunct, an axoneme (9+9+2) and two accessory bodies. The head shows ...
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