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A numerical study of a radio frequency transceiver coil incorporating a capacitive metasurface is investigated for 1.5T magnetic resonance imaging of the cervical spinal cord. Full field simulations are carried out using the head of a human body model where the magnetic flux density (B1−) is compared to a standard transceiver coil. It is shown that an average improvement in B1− of 70% can be observed...
An optimized Metamaterial line resonator element for a Metamaterial imaging RF coil is developed for the ultrahigh field MRI systems. The coil element performance is compared to that of the transmission line (microstrip) [1] and the dipole [2,5] coil elements for the 10.5T MRI with a Larmor frequency of 447 MHz. Good penetration into the test phantom is observed for the Metamaterial element with negligible...
We review our recent work on the application of advanced electromagnetic structures for Magnetic Resonance Imaging. We discuss the use of metasurfaces and metamaterials resonators in order to locally enhance the sensitivity of radiofrequency coils in daily medical examinations. We will show in particular our recent experimental results about giant signal-to-noise ratio enhancement by arrays of nonmagnetic...
The contribution presents a perspective approach to increasing the sensing coil's working range in magnetic resonance imaging using a planar resonant structures with distributed parameters. The working range increase consists in the improvement of homogeneity of the RF magnetic field generated by the coil. In the contribution, a novel resonant structure - Grid Quasi-Periodic Resonant structure, is...
We reveal that the unique properties of ultrathin metasurface resonators can improve dramatically magnetic resonance imaging (MRI). We place a metasurface formed by an array of metallic wires inside a scanner under the studied object and achieve a substantial enhancement of the radiofrequency magnetic field by means of subwavelength near-field manipulation with metasurface, also allowing to improve...
Metasurfaces are artificial two-dimensional structures with subwavelength periodicity. A shape and a size of the unit cells are responsible for electromagnetic properties of a metasurface. Metasurfaces provide specific boundary conditions which define the reflection and transmission properties with respect to incident plane waves. In the present work, we consider the structure based on the so-called...
A Zeroth Order microstrip resonator (ZOR) is proposed as an element for a MRI transmission line RF coil. This paper discusses a design of the ZOR for the RF coil for a 7T MRI system. A balanced metamaterial line is used to achieve broadside radiation. The design has the advantage of generating uniform strong near field up to a vicinity of 3 cm from its surface, and requires minimal tuning and matching...
Metamaterials have great potential for the practical applications of electromagnetic wave absorption. Therefore, it is important to understand the mechanism of the metamaterial based electromagnetic wave absorbers. In this paper, the design, simulation, fabrication and measurement of a polarization independent dual-band metamaterial absorber is presented in the microwave region. The proposed meta-material...
Metamaterial based radio frequency (RF) surface coils are investigated for magnetic resonance imaging (MRI) applications. The utilization of the metamaterial is expected to enhance the magnetic field intensity of the surface coils and improve the signal to noise ratio (SNR) of the MRI system. Two types of metamaterials, namely the metamaterial structures with negative permeability (µr) or high permeability,...
In this paper, Smith-Purcell effect, which utilizes metallic grating and electron bunches, was investigated for a new device of terahertz (THz)-wave generation. Femtosecond electron bunches induced multimode THz-wave at a frequency of <0.7 THz.
We propose an adaptive RF antenna system for the excitation (and manipulation) of the fundamental circular waveguide mode (TE11) in the context of high-field (7T) traveling-wave magnetic resonance imaging (MRI). The system consists of «flat» composite right-/left-handed (CRLH) meta-material ring antennas that fully conforms to the inner surface of the MRI bore. The specific use of CRLH metamaterials...
Since the 1960's, Magneto-optic (MO) garnet materials have been studied extensively. These materials can possess world-record MO performance characteristics in terms of Faraday rotation and optical quality. Among the rear-earth-doped garnets, the Bi-substituted iron garnet is the best candidate for use as a functional material in different integrated-optics, imaging/image processing applications and...
The possibility of using composite right/left-handed (CRLH) zeroth-order resonant antennas (ZORAs) in magnetic resonance imaging (MRI) to provide the highly uniform RF magnetic field required for high-quality MRI is explored. A series-mode metal-insulator-metal (MIM) CRLH zeroth-order resonant ldquocoilrdquo (ZORC) element is proposed for this purpose. This ZORC element is shown to provide a very...
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