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Results 201 - 250 of 939
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Mager Dario - - 2010
Inkjet printing has been used to produce resonant radio frequency coils that are comparable to those produced by conventional printed circuit board (PCB) methods. The coils, which consist of a conductive loop and in-series capacitors, form part of a receiver circuit that is used for magnetic resonance imaging (MRI). The ...
Webb Andrew G - - 2010
Using a small resonant loop to produce a longitudinal traveling wave on a human 7-T system allows MR to be performed over the entire volume of the human leg. We have used this capability to perform localized proton MR spectroscopy of the lipid composition of muscle in volunteers with a ...
Burke B - - 2010
The integration of medical linear accelerators (linac) with magnetic resonance imaging (MRI) systems is advancing the current state of image-guided radiotherapy. The MRI in these integrated units will provide real-time, accurate tumor locations for radiotherapy treatment, thus decreasing geometric margins around tumors and reducing normal tissue damage. In the real-time ...
Jeong Sang Young - - 2010
Biocompatible poly-[N-(2-hydroxyethyl)-d,l-aspartamide]-methoxypoly(ethyleneglycol)-hexadecylamine (PHEA-mPEG-C(16)) conjugated with 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid-gadolinium (DOTA-Gd) via ethylenediamine (ED) was synthesized as a magnetic resonance imaging (MRI) contrast agent. Amphiphilic PHEA-mPEG-C(16)-ED-DOTA-Gd forms micelle in aqueous solution. All the synthesized materials were characterized by proton nuclear magnetic resonance ((1)H NMR). Micelle size and shape were examined by dynamic light ...
Constantinides C - - 2010
The idea of a novel MR surface coil based on multi-turn spiral geometry is presented for use in mouse cardiac MRI. The benefits from flat, cylindrical arrangement of the coil are compared using computer simulations and MRI experiments in various cases of free space, phantom and animal loading conditions. Results ...
Asfour Aktham - - 2010
We present in this paper a dedicated home-built RF probe-head for the MRI of rat brain at 2.35 T. This probe consists of an association of three coils: a double-tuned birdcage coil, which could be used for both transmitting and receiving, and a single-tuned surface coil that is used for ...
Lee Ray F - - 2010
One of the major functions of the human brain is to mediate interactions with other people. Until recently, studying brain social interactions has not been possible due to the lack of measurable methods to observe two interacting minds simultaneously. We have developed a novel dual-head MRI coil that can scan ...
Martini N - - 2010
The acquisition of magnetic resonance spectroscopy (MRS) signals by multiple receiver coils can improve the signal-to-noise ratio (SNR) or alternatively can reduce the scan time maintaining a reliable SNR. However, using phased array coils in MRS studies requires efficient data processing and data combination techniques in order to exploit the ...
Solis S E - - 2010
The effect of the shielding in a PET-MRI system was numerically estimated by calculating the RF magnetic field, B1, produced by a coil array of 4 independent elements at the resonant frequency of 171 MHz (4T for protons). The array coil is located inside a μPET camera to simultaneously acquire ...
Schuck A - - 2010
A new class of wavelet functions called data-based autocorrelation wavelets is developed for analyzing Magnetic Resonance Spectroscopic (MRS) signals by means of the continuous wavelet transform (CWT), instead of the traditional wavelet like Morlet wavelet. These new wavelets are derived from the normalized autocorrelation function from metabolite data and then ...
Gongidi Preetam - - 2010
Gout is a systemic, metabolic disease that typically affects the peripheral joints. We describe an unusual presentation of gout affecting the facet joints and costovertebral joints in the thoracic and lumbar spine. A 54-year old man presents to the emergency department with increasing swelling and pain at the left elbow ...
He Bo B Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, - - 2010
The recent development of 1D barcode arrays has proved their capabilities to be applicable to highly multiplexed bioassays. This article introduces two magnetic decoding protocols for suspension arrays of shape-coded silica nanotubes to process multiplexed assays rapidly and easily, which will benefit the minimization and automation of the arrays. In ...
Kickler Nils N Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland. - - 2010
Eddy currents induced by switching of magnetic field gradients can lead to distortions in short echo-time spectroscopy or diffusion weighted imaging. In small bore magnets, such as human head-only systems, minimization of eddy current effects is more demanding because of the proximity of the gradient coil to conducting structures. In ...
Takahara Taro - - 2010
OBJECTIVE: To introduce and assess a new way of performing whole-body magnetic resonance imaging (MRI) using a non-integrated surface coil approach as available on most clinical MRI systems worldwide. METHODS: Ten consecutive asymptomatic subjects prospectively underwent whole-body MRI for health screening. Whole-body MRI included T1-, T2- and diffusion-weighted sequences, and ...
Gilbert Guillaume - - 2009
RATIONALE AND OBJECTIVES: To investigate the ability of an intravascular magnetic resonance (MR) loopless antenna to reduce the radiofrequency shielding of a vascular stent during signal reception as a way to improve the visualization of the in-stent lumen. METHODS AND MATERIALS: Using a balanced steady-state free-precession (bSSFP) sequence and a ...
Rengle Adrian - - 2009
In the field of small animal studies, the array coil imaging has become increasingly important. In this paper, a dedicated two-channel array coil operating at 300 MHz (7 T) for high-resolution MRI (HR-MRI) of the rat knee cartilage is presented. The average gain in signal-to-noise ratio (SNR) compared to a ...
Hayes Cecil E - - 2009
The author gives a personal account of the development of the birdcage resonator while he worked at GE Medical Systems. The emphasis is on promoting an intuitive understanding of the underlying principles of RF coil design by recounting the assumptions, misconceptions, and reasoning involved in addressing the challenging problems in ...
Neuberger Thomas - - 2009
Given the several orders of magnitude fewer spins per voxel for MR microscopy than for conventional MRI, efficient coil design is important to obtain sufficient signal-to-noise within reasonable data acquisition times. As MR microscopy is typically performed using very high magnetic fields, coil design must also incorporate the effects of ...
Uecker Martin - - 2009
Each k-space segment in multishot diffusion-weighted MRI is affected by a different spatially varying phase which is caused by unavoidable motions and amplified by the diffusion-encoding gradients. A proper image reconstruction therefore requires phase maps for each segment. Such maps are commonly derived from two-dimensional navigators at relatively low resolution ...
Sim Jae Hoon - - 2009
The inability to identify 3-D force and moment components for actuators and sensors is a major limiting factor in the study of 3-D force interactions with small-scale biological structures. While recent advances have been made in the measurement of stimulating forces using load cells and atomic-force microscopy in experimental preparations ...
Wu Bing - - 2010
The high-frequency transceiver array based on the microstrip transmission line design is a promising technique for ultrahigh field magnetic resonance imaging (MRI) signal excitation and reception. However, with the increase of radio-frequency (RF) channels, the size of the ground plane in each microstrip coil element is usually not sufficient to ...
Matsuoka Yuichiro - - 2010
The laparoscope has been invaluable in minimally invasive surgery, but provides only a surface view of target tissue; therefore it is lacking internal tissue information. In combination with the laparoscope for visualizing the cross-sectional view of the tissue, MRI is superior to ultrasonography or X-ray CT, because of its high ...
Baltes Christof - - 2009
The increasing number of mouse models of human disease used in biomedical research applications has led to an enhanced interest in non-invasive imaging of mice, e.g. using MRI for phenotyping. However, MRI of small rodents puts high demands on the sensitivity of data acquisition. This requirement can be addressed by ...
Burmeister Hartmut Peter - - 2009
PURPOSE: This study examines the identifiability of the intratemporal motor facial nerve using 3-T and 1.5-T magnetic resonance imaging (MRI). METHODS: Twenty subjects underwent T1- and T2-weighted MRI of the temporal bone. Acquisition was performed using a head coil at 3 and 1.5 T as well as a surface coil ...
Fan Bo-Guang - - 2009
Since the autoimmune pancreatitis was introduced in 1995, it has been recognized as a form of chronic pancreatitis, which is always associated with autoimmune manifestations. As the improvement of technical and instrumental made in ultrasonography, computed tomography and magnetic resonance imaging, the diagnoses of autoimmune pancreatitis is no longer such ...
Hanvey S - - 2009
This study investigated the compatibility of a head and neck immobilization device with magnetic resonance imaging (MRI). The immobilization device is used to position a patient in the same way as when receiving a computed tomography (CT) scan for radiotherapy planning and radiation treatment. The advantage of using immobilization in ...
Detorakis Efstathios T - - 2009
PURPOSE: To evaluate position and function of antiglaucomatous Ahmed and Molteno shunts using magnetic resonance imaging with head and surface coils. METHODS: Eight patients (5 males) with shunt implants were included, 4 with Ahmed (FP-7) and 4 with Molteno (s1, single plated). All patients were operated at least 6 months ...
Konoto M - - 2009
A surface decontamination system for application in surface sensitive magnetic imaging tools, such as a spin-polarized scanning electron microscope, is described. Adsorbed contaminant is chemically decomposed with the use of active oxygen in a compact vacuum chamber mounted in a microscope. The present method is especially suitable for fragile magnetic ...
Assemlal Haz-Edine - - 2009
We present a method for the estimation of various features of the tissue micro-architecture using the diffusion magnetic resonance imaging. The considered features are designed from the displacement probability density function (PDF). The estimation is based on two steps: first the approximation of the signal by a series expansion made ...
Blasiak Barbara - - 2009
Applications of low-field magnetic resonance imaging (MRI) systems (<0.3 T) are limited due to the signal-to-noise ratio (SNR) being lower than that provided by systems based on superconductive magnets (> or = 1.5 T). Therefore, the design of radiofrequency (RF) coils for low-field MRI requires careful consideration as significant gains ...
Demyanenko Andrey V - - 2009
We present an optimized uniplanar magnetic resonance gradient design specifically tailored for MR imaging applications in developmental biology and histology. Uniplanar gradient designs sacrifice gradient uniformity for high gradient efficiency and slew rate, and are attractive for surface imaging applications where open access from one side of the sample is ...
Verduijn Gerda M - - 2009
PURPOSE: To optimize the use of MRI for delineation of gross tumor volume for radiotherapy treatment planning purposes in hypopharyngeal and laryngeal tumors. METHODS AND MATERIALS: Magnetic resonance images (T1 weighted and T2 weighted) of a healthy volunteer were acquired using a 1.5 T and 3.0 T MR scanner. Various ...
Adachi Satoru - - 2009
A compact magnetic resonance imaging (MRI) system for a cold (-5 degrees C) room has been developed to acquire MR images below the freezing point of water. The MRI system consists of a 1.0 T permanent magnet, a higher-order shim coil set, and a gradient coil probe, installed in the ...
Folkesson Jenny - - 2009
Magnetic resonance (MR) imaging-based quantitative trabecular bone structure analysis has gained increasing interest in osteoporotic fracture risk assessment and treatment evaluation related to osteoporosis. In vivo MR images of anatomic regions such as the proximal femur and distal tibia are generally acquired with a surface coil in order to obtain ...
Schlamann Marc - - 2009
Endoscopy for evaluation of hoarseness is an invasive procedure and the result depends, to a large extent, on the patient's cooperation. Successful laryngoscopy can also be hampered by unfavourable anatomic conditions, a severely impaired general condition, or severe coagulopathy. We evaluated the feasibility of doing ultra-fast magnetic resonance imaging (MRI), ...
Eryaman Yiğitcan Y Department of Electrical and Electronics Engineering, Bilkent University, 06800 Ankara, Turkey. - - 2009
Internal MRI coils have important applications in diagnostic and interventional studies. Since they can be placed very close to the region of interest in the body, they are favored over external coils in applications where high-resolution images are required. In this paper it is demonstrated that ultimate intrinsic SNR (UISNR) ...
Aubry Sébastien - - 2009
The purpose of this study was to assess the quality of 3-T magnetic resonance (MR) imaging of the skin, to describe skin anatomy at 3 T and to discuss future prospects of skin MRI. A 7-cm single-element surface receiver coil was developed for our 3-T MRI system. Thin sections were ...
van der Zwaag Wietske - - 2009
In this investigation, high-resolution, 1x1x1-mm(3) functional magnetic resonance imaging (fMRI) at 7 T is performed using a multichannel array head coil and a surface coil approach. Scan geometry was optimized for each coil separately to exploit the strengths of both coils. Acquisitions with the surface coil focused on partial brain ...
Andoh Jamila - - 2009
Transcranial magnetic stimulation (TMS) is currently used for cognitive studies and investigated as a treatment for psychiatric disorders. Because of the cortex variability, the coil positioning stage is difficult and should be improved by using individual neuroimaging data. Sophisticated and expensive neuronavigation systems have been developed to guide the coil ...
Roy Catherine - - 2009
OBJECTIVE: The purpose of this retrospective study was to evaluate the accuracy of MRI using pelvic-phased-array and endocavitary coils in detecting intestinal wall invasion by an endometriotic nodule. MATERIALS AND METHODS: Forty-seven patients (32.1 +/- 4.2 years) who were planned for a surgical cure of deep endometriosis underwent MRI with ...
Gabr Refaat E - - 2009
As the number of MRI phased array coil elements grows, interactions among cables connecting them to the system receiver become increasingly problematic. Fiber optic or wireless links would reduce electromagnetic interference, but their dynamic range (DR) is generally less than that of coaxial cables. Raw MRI signals, however, have a ...
Lattanzi Riccardo - - 2009
The promise of increased signal-to-noise ratio and spatial/spectral resolution continues to drive MR technology toward higher magnetic field strengths. SAR management and B1 inhomogeneity correction become critical issues at the high frequencies associated with high field MR. In recent years, multiple coil excitation techniques have been recognized as potentially powerful ...
Ha Yong H - - 2009
We introduce a magnetic navigation of a small magnet using four stationary coils. We used a Maxwell gradient coil to get magnetic propulsion force and three Helmholtz coils to control the moving direction of the magnet in the magnetic navigation. Using a three-channel coil driver with output capacity of 320A, ...
Noor Furqan - - 2009
The design of an inductive power system is investigated in order to determine the relative benefits provided by the inclusion of a magnetic core in the receiver coil. Both transmitter and receiver coils are chosen to have dimensions similar to those used in many biomedical devices. It is found that ...
Kocaturk Ozgur - - 2009
BACKGROUND: Catheter visualization and tracking remains a challenge in interventional MR.Active guidewires can be made conspicuous in "profile" along their whole shaft exploiting metallic core wire and hypotube components that are intrinsic to their mechanical performance. Polymer-based catheters, on the other hand, offer no conductive medium to carry radio frequency ...
Katscher Ulrich - - 2009
The electrical conductivity of human tissue could be used as an additional diagnostic parameter or might be helpful for the prediction of the local SAR during MR measurements. In this study, the approach "Electric Properties Tomography" (EPT) is applied, which derives the patient's electric conductivity using a standard MR system. ...
Duan Yunsuo - - 2009
PURPOSE: To optimize the homogeneity and efficiency of the B(1) magnetic field of a four-ring birdcage head coil that is double-tuned at the Larmor frequencies of both (31)P and (1)H and optimized to acquire magnetic resonance spectroscopy (MRS) data at 3T for the study of infants. MATERIALS AND METHODS: We ...
Sundareswaran Kartik S - - 2009
To develop and validate a multidimensional segmentation and filtering methodology for accurate blood flow velocity field reconstruction from phase-contrast magnetic resonance imaging (PC MRI). The proposed technique consists of two steps: (1) the boundary of the vessel is automatically segmented using the active contour approach; and (2) the noise embedded ...
Morita Yoshinori - - 2009
BACKGROUND: The purpose of this study was to visualize the gastric wall layers and to depict the vascular architecture in vitro by using resected porcine stomachs studied with high-spatial resolution magnetic resonance (MR) imaging. METHODS: Normal dissected porcine stomach samples (n = 4) were examined with a 3 Tesla MR ...
Bashir Adil - - 2009
MRI with hyperpolarized gases, (3)He, (129)Xe, (13)C, and others, has the potential to become an important diagnostic technique for clinical imaging. Due to the nonreversible loss of magnetization in hyperpolarized gas imaging, the choice of the flip angle is a major factor that influences the signal intensity, and hence, the ...
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