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 ...

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 ...

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. ...

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, ...

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 ...

Summary: 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.

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 ...

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 ...

AIM OF THE STUDY: To compare high resolution MRI examinations of inner ear structures at 1.5 T and at 3 T. METHOD: Temporal bones were measured bilaterally in 3 healthy volunteers in a 1.5 T and in a 3 T MR-scanner using the respective one channel head coil (quadrature detection) ...

OBJECTIVE: Surface magnetic resonance imaging (MRI) for aortic plaque assessment is limited by the trade-off between penetration depth and signal-to-noise ratio (SNR). For imaging the deep seated aorta, a combined surface and transesophageal MRI (TEMRI) technique was developed 1) to determine the individual contribution of TEMRI and surface coils to ...

Parallel imaging using multiple receiver coils has emerged as an effective tool to reduce imaging time in various MRI applications. When a large number of receiver channels are used to achieve large acceleration factors, the image reconstruction problem can become very ill conditioned. This problem can be alleviated by optimizing ...

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 ...

We propose that the meridian system as a whole is one grand transmission line, excited periodically at a frequency of f50, the frequency of the 50-round circulation (0.578 x 10(-3) Hz). This grand transmission line is analyzed as a 28-leg, uniform, low pass (LP) electromagnetic (EM) birdcage coil, consisting of ...

We have taken random image noise into consideration in the contrast-to-gradient (CG) method for the evaluation of image resolution R in scanning electron microscopy (SEM). When looking at the local fine pattern in the SEM micrograph containing much random noise, viewers gradually expand the region of interest (ROI) to improve ...

Key challenges for design of intravascular loop probes are minimization of the cross sectional and length while increasing signal-to-noise ratio (SNR). Although NPO grade captors under 1mm dimensions are now available, the impedance matching network components still constrain tunability. In this study, a new loop probe is proposed for intravascular ...

Structural and functional magnetic resonance imaging of the newborn brain is a complex and challenging task. Term and preterm neonates require a controlled microenvironment and close monitoring during the MRI study to maintain respiratory and cardiovascular functions, body temperature, and fluid and electrolyte homeostasis. In addition, to minimize motion artifacts, ...

Tip integrity is crucial to atomic force microscope image quality. Tip wear not only compromises image resolution but also introduces artifacts. However, the factors that govern wearing have not been systematically studied. The results presented here of tip wearing on a rough titanium surface were determined by monitoring changes in ...

Intramyocellular lipid (IMCL) plays an important role in the study of metabolism in vivo. Magnetic resonance spectroscopy (MRS) studies of IMCL are usually performed with clinical 1.5-T magnetic resonance imaging (MRI) systems and have employed the single-voxel MRS technique. The present study reports the results of our systematic evaluation of ...

Atomic force microscopy analysis of polyhydroxyalkanoate (PHA) inclusions isolated from sonicated Ralstonia eutropha cells revealed that they exhibit two types of surface structure and shape; rough and ovoid, or smooth and spherical. Smooth inclusions possessed linear surface structures that were in parallel arrays with 7-nm spacing. Occasionally, cracks or fissures ...

The performance of the stimulation coil in a magnetic nerve stimulator can be improved by attaching a ferromagnetic structure to the coil. This reduces heat generation at the coil and increases magnetic field strength for a given unit of current. Some technical aspects of the design of a stimulation coil ...

A neural-network-based framework has been developed to search for an optimal wavelet kernel that can be used for a specific image processing task. In this paper, a linear convolution neural network was employed to seek a wavelet that minimizes errors and maximizes compression efficiency for an image or a defined ...

OBJECTIVE: To compare MR images of the triangular fibrocartilage complex (TFCC) using microscopy coils with those using a conventional surface coil qualitatively and quantitatively. DESIGN AND PATIENTS: Proton density-weighted images and T2*-weighted images of the TFCC from ten normal volunteers were obtained with a conventional surface coil (C4 coil; 80 ...

We compress phase-shift digital holograms (whole Fresnel fields) for the transmission of three-dimensional images. For real-time networking applications, the time required to compress can be as critical as the compression rate. We achieve lossy compression through quantization of both the real and imaginary streams, followed by a bit packing operation. ...

Localized versions of two-dimensional (2D) magnetic resonance spectroscopic (MRS) sequences, namely JPRESS and L-COSY, have been implemented on a whole-body 3T MRI/MRS scanner. Volume selection was achieved using three slice-selective radio-frequency (RF) pulses: 90 degrees-180 degrees-180 degrees in JPRESS and 90 degrees-180 degrees-90 degrees in L-COSY with a CHESS sequence ...

Magnetic resonance (MR) systems operating at 3 Telsa (T) and above have demonstrated considerable potential in human studies, offering improved signal-to-noise ratio and spectral resolution. However, because of radiofrequency limitations and concerns, and the lack of large volume body coils, most studies have been limited to the head. In this ...

PURPOSE: The aim of this work was to compare the knee coil and the surface coil for the visualisation of the patellar cartilage. MATERIALS AND METHODS: In 28 patients (17 women, 11 men) with an average age of 40 years (range 14-76) with knee pain MR was performed. Transverse images ...

The wide variety of available surface coils, pulse sequences, and post-processing techniques make MR imaging a useful clinical and research tool for evaluation of pelvic floor relaxation. Cases of isolated cystocele do not require imaging; however, in cases in which multiple compartments of the pelvis are involved or the patient ...

We consider the commonly used "Sum-of-Squares" (SoS) reconstruction method for phased-array magnetic resonance imaging with unknown coil sensitivities. We show that the signal-to-noise ratio (SNR) in the image produced by SoS is asymptotically (as the input SNR--> infinity ) equal to that of maximum-ratio combining, which is the best unbiased ...

Quantization of the coefficients within a discrete wavelet transform subband gives rise to distortions in the reconstructed image that are localized in spatial frequency and orientation and are spatially correlated with the image. We investigated the detectability of these distortions: Contrast thresholds were measured for both simple and compound distortions ...

In this paper I review our experiments on visualization of discrete breathers (intrinsic localized modes) in nonlinear lattices made of Josephson junctions. Properties of Josephson junctions and arrays made of such junctions are discussed in the Introduction. The visualization technique based on low temperature laser scanning microscopy (LSM) is described ...

Inductively coupled solenoid coils fitting to objects in the size of mice or rats were developed to adapt modem whole-body MR scanners featuring sufficient gradient strength for animal examinations with high spatial resolution. Homogenous receiver characteristics is achievable over almost the whole inner region of the solenoid coils. The SNR ...

PURPOSE: To examine peripheral nerve stimulation (PNS) thresholds for normal human subjects in magnetic resonance imaging (MRI) gradient coils, and determine if observed thresholds could be predicted based on gross physiologic measurements. MATERIALS AND METHODS: PNS thresholds for 21 healthy normal subjects were measured using a whole-body gradient coil. Subjects ...

The mechanical nature of gastric contraction activity (GCA) plays an important role in gastrointestinal motility. The aim of this study was to detect GCA in anaesthetized dogs, using simultaneously the techniques of AC biosusceptometry (ACB) and manometry, analysing the characteristics of frequency and amplitude (motility index) of GCA, modified by ...

Sensitivity encoding (SENSE) uses multiple MRI receive coil elements to encode spatial information in addition to traditional gradient encoding. Requiring less gradient encodings translates into shorter scan times, which is extremely beneficial in many clinical applications. SENSE is available to routine diagnostic imaging for the past 2 years. This paper ...

A high-frequency RF volume coil based on the use of microstrip transmission line (MTL) has been developed for in vivo 1H MR applications on the human head at 4T. This coil is characterized by major advantages: (i) completely distributed coil circuit, (ii) high-quality factor (Q), (iii) simple coil structure, and ...

A study of first-order Talbot resonators is presented. The general conditions for Talbot effect in ABCD systems are determined. These conditions are applied to the computation of the diffraction overlapping coefficients between array Gaussian emitters in a general first-order Talbot resonator. Relations on the ray-transfer matrix to generate the symmetric ...

Retrograde urethrography is the method commonly employed in the detection of anterior male urethra pathology. Ultrasonography and magnetic resonance imaging have been proposed recently as new methods that can replace conventional radiography. Normal urethral anatomy can be easily studied after saline distention of the urethra, which creates high contrast relative ...

PURPOSE: To investigate the efficacy of passive acoustic screening in the magnetic resonance (MR) environment by reducing direct and indirect MR-related acoustic noise, both from the patient's and health worker's perspective. MATERIALS AND METHODS: Direct acoustic noise refers to sound originating from the inner and outer shrouds of the MR ...

The use of detached endcaps for 3 T birdcage coils was investigated both theoretically and experimentally. Finite difference time domain analysis, along with workbench and MRI techniques, were used to map the radiofrequency (RF) B(1) distribution along the coil axis with and without an endcap. Without an endcap the measured ...

OBJECTIVE: MRI is being used to characterize the composition of atherosclerotic plaques. However, the resolution achievable using surface radiofrequency coils is limited by the signal to noise ratio. We studied the utility of a new intravascular (IV) MRI probe for high-resolution in vivo imaging of atherosclerotic lesions. METHODS AND RESULTS: ...

PURPOSE: To test the hypotheses that a single internal guide wire coil (i) permits independent and direct depiction of guide wires and catheters and (ii) improves catheter-tracking accuracy and depiction compared to external receiver coils. MATERIALS AND METHODS: Standard 5-6-F angiographic catheters were filled with dilute 4% gadolinium chelate. A ...

INTRODUCTION: While it is desirable to perform MRI examinations in patients with deep brain stimulators (DBS), a major safety concern exists regarding the potential for excessive heating secondary to magnetically induced electrical currents. This study was designed to determine the safety of MRI and DBS. METHODS: Standard configurations of DBS ...

Based on a local spatial/frequency representation,we employ a spectral histogram as a feature statistic for texture classification. The spectral histogram consists of marginal distributions of responses of a bank of filters and encodes implicitly the local structure of images through the filtering stage and the global appearance through the histogram ...

A layered depth image (LDI) is a new popular representation and rendering method for objects with complex geometries. Similar to a two-dimensional (2-D) image, the LDI consists of an array of pixels. However, unlike the 2-D image, an LDI pixel has depth information, and there are multiple layers at a ...

This paper describes the performance of the MPEG-4 still texture image codec in coding noisy images. As will be shown, when using the MPEG-4 still texture image codec to compress a noisy image, increasing the compression rate does not necessarily imply reducing the peak-signal-to-noise ratio (PSNR) of the decoded image. ...

Cavernous hemangioma of the rectum (CHR) is an uncommon benign vascular lesion, which mainly affects young adults. The rectosigmoid area is the most common site of cavernous hemangioma in the gastrointestinal tract. CHR is often misdiagnosed due to a lack of knowledge of the clinical features. We report a case ...

OBJECT: The authors report on a new head coil into which the Leksell aluminum localization frame can be easily and securely mounted. Mechanically, the head coil interferes little with the patient. METHODS: The head coil, which is for magnetic resonance (MR) imaging, is a 12-element quadrature transmit-and-receive high-pass birdcage coil ...

To provide effective contraception and protection against sexually transmitted disease, vaginal gels should maximally cover the cervical os and the vaginal epithelium before, during and after intercourse. To non-invasively monitor the intravaginal distribution of an applied intravaginal gel, we performed high-resolution magnetic resonance imaging (MRI) of the female pelvis before, ...

BACKGROUND: An electronic radial array echoendoscope has been developed that uses the same US processor as the linear array instruments made by the same company, thereby eliminating the need for two processors. The performance of this prototype instrument was compared with that of a mechanical radial echoendoscope in patients. METHODS: ...

Radio-frequency (RF) coils are a necessary component of magnetic resonance imaging (MRI) systems. When used in transmit operation, they act to generate a homogeneous RF magnetic field within a volume of interest and when in receive operation, they act to receive the nuclear magnetic resonance signal from the RF-excited specimen. ...