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The specific absorption rate produced in a rat’s brain phantom inside of quadrature birdcage coil as a function of the rung number was studied at 300MHz. Electromagnetic field simulations and specific absorption rate and loss return responses were performed using a rat’s brain phantom weighing 100mg. To assure optimal simulations and to evaluate coil performance, S-parameters were simulated and compared...
A variant coil of the high frequency cavity resonator coil was experimentally developed according to the theoretical frame proposed by Mansfield in 1990. This coil design is similar to the popular birdcage coil but it has the advantage that it can be easily built following the physical principles of the cavity resonators. The equivalent circuit approach was used to compute the resonant frequency of...
An image based method to compute the signal to noise ratio and specific energy absorption rate of MRI surface resonator coil for different polygonal geometries is proposed. A commercial software tool based on the Finite Element Method was used to numerically solve the Maxwell's equations to form bidimensional images of the electric and magnetic fields. These images represent the point by point fields...
Coil arrays have become a very popular coil configuration for magnetic resonance imaging. This due to that, an image of a larger area can be obtained with uniform sensitivity and higher SNR as compared to standard MR volume coil. Ultra-fast procedures like parallel imaging and phased-array can take advantage of these properties. It is very important to understand the performance of this type of devices...
A new coil design inspired on the slot-and-hole magnetron tube is proposed for SENSE imaging. To investigate its g-factor behaviour: an SNR formula was derived using the quasi-static approach, and combined with the ultimate g-factor formula to compute the ultimate-factor-g-vs-depth plots. A g-factor expression was derived for the circular coil using the same approach for comparison purposes. SNR-vs-depth...
Methods to predict fragmentation efficiency are still needed for extracorporeal shock wave lithotripsy (ESWL). Imaging studies of kidney stones could be a useful tool to guide ESWL. Artificial and real kidney stones were analyzed using standard clinical CT imaging procedures. The objective was to compare CT image properties of phantom and real kidney stones. Image properties of both groups were compared...
The coil separation of phased-array coils is an important issue if a wide area of interest is to be imaged. An equivalent circuit of two circular-shaped coils was used to compute the optimal distance in a two phased-array coil. This circuit included the mutual inductance of two circular coils. An expression for the mutual inductance was derived and the resulting values included in the circuit. With...
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 a specific layout of two coils with 4 rectangular-shaped coils each. Computational experiments...
20 patients with stroke more than one year earlier were evaluated, admitted to a novel therapy including constraint-induced and computer game-motivated therapy. Statistically significant improvements after 4 weeks of late therapy were seen in all 20 patients on nine out of eleven quantified clinical evaluation scales. The patients looked forward to and enjoyed the therapy. These same late stroke patients...
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