scholarly journals Subject-loaded quadrifilar helical-antenna RF coil with high B1+field uniformity and large FOV for 3-T MRI

2016 ◽  
Vol 46B (3) ◽  
pp. 106-117 ◽  
Author(s):  
Pranav S. Athalye ◽  
Nada J. Šekeljić ◽  
Milan M. Ilić ◽  
Alexey A. Tonyushkin ◽  
Branislav M. Notaroš
Keyword(s):  
Rf Coil ◽  
Helical Antenna ◽  
Field Uniformity ◽  
B1 Field

scholarly journals Design and Implementation of Split-Leg Type Elliptical Whole-Body Birdcage RF Coil at 1.5 T MRI

2021 ◽  
Vol 11 (16) ◽  
pp. 7448
Author(s):  
Suchit Kumar ◽  
Han-Jae Chung ◽  
You-Jin Jeong ◽  
Heung-Kyu Lee ◽  
Chang-Hyun Oh
Keyword(s):  
Human Subjects ◽  
Three Dimensional ◽  
System Optimization ◽  
Transmission Efficiency ◽  
Human Model ◽  
Whole Body ◽  
Rf Coil ◽  
Field Uniformity ◽  
B1 Field

The feasibility and the development of a four-port elliptical birdcage radio frequency (RF) coil for generating a homogenous RF magnetic (B1) field is presented for a space-constrained narrow-bore magnetic resonance imaging (MRI) system. Optimization was performed for the elliptical birdcage RF coil by adjusting the position and the structure of the legs to maximize the B1+-field uniformity. Electromagnetic (EM) simulations based on RF coil circuit co-simulations were performed on a cylindrical uniform phantom and a three-dimensional human model to evaluate the B1+-field uniformity, the transmission efficiency, and the specific absorption rate (SAR) deposition. An elliptical birdcage RF coil was constructed, and its performance was evaluated through network analysis measurements such as S-parameters and Q-factor. Quadrature transmit and receive MRI experiments were conducted using both phantom and in vivo human for validation. The EM simulation results indicate reasonable B1+-field uniformity and transmission efficiency for the proposed elliptical birdcage RF coil. The signal-to-noise ratio and the flip angle maps of the uniform phantom and the in vivo human MR images acquired using an elliptical birdcage (62 cm × 58 cm) were similar to those of a commercial circular birdcage (diameter, 58 cm), thereby indicating acceptable performance. In conclusion, the proposed split-type asymmetric elliptical birdcage RF coil is useful for whole-body MRI applications and can be used for imaging larger human subjects comfortably in a spacious imaging space.

scholarly journals Design of a Coplanar Interlayer Gapped Microstrips Arrangement for Multi-Nuclei (1H, 19F, 31P, and 23Na) Applications in 7T MRI

2021 ◽  
Vol 11 (3) ◽  
pp. 957
Author(s):  
Daniel Hernandez
Keyword(s):  
Magnetic Resonance ◽  
Dielectric Materials ◽  
Rf Coil ◽  
High Quality ◽  
Anatomical Images ◽  
B1 Field ◽  
Materials Used ◽  
Current Lines ◽  
A Current ◽  
Metabolic Information

Seven Tesla Magnetic Resonance (MR) systems can obtain high quality anatomical images using protons (1H) and can be used for multinuclear imaging and MR spectroscopy. These imaging modes can also obtain images and metabolic information using other nuclei, such as 19F, 31P, and 23Na. Here, we present an RF coil unit using a microstrip capable of resonating at four frequencies: 300 (1H), 280 (19F), 121 (31P), and 78 (23Na) MHz. The RF unit consists of a single feeding port and four lines that resonate and run a current at their respective frequency. We used the gapped microstrip concept to isolate each conducting line and interleaved the dielectric materials used for each line, thereby reducing the coupling between them. We also analyzed this design using electromagnetic (EM) simulations, and found that the quad tuned arrangement produced low coupling between adjacent current lines and achieved a uniform |B1| field in the z-y plane.

Analysis of field uniformity and quantitative evaluation of subsurface pitting corrosion in conductors via GPEC

2020 ◽  
Vol 64 (1-4) ◽  
pp. 19-29
Author(s):  
Shuting Ren ◽  
Yong Li ◽  
Bei Yan ◽  
Jinhua Hu ◽  
Ilham Mukriz Zainal Abidin ◽  
...  
Keyword(s):  
Quantitative Evaluation ◽  
Eddy Current ◽  
Pitting Corrosion ◽  
Gradient Field ◽  
Uniform Field ◽  
Eddy Current Method ◽  
Optimal Position ◽  
Pulsed Eddy Current ◽  
Field Uniformity ◽  
Processing Algorithms

Structures of nonmagnetic materials are broadly used in engineering fields such as aerospace, energy, etc. Due to corrosive and hostile environments, they are vulnerable to the Subsurface Pitting Corrosion (SPC) leading to structural failure. Therefore, it is imperative to conduct periodical inspection and comprehensive evaluation of SPC using reliable nondestructive evaluation techniques. Extended from the conventional Pulsed eddy current method (PEC), Gradient-field Pulsed Eddy Current technique (GPEC) has been proposed and found to be advantageous over PEC in terms of enhanced inspection sensitivity and accuracy in evaluation and imaging of subsurface defects in nonmagnetic conductors. In this paper two GPEC probes for uniform field excitation are intensively analyzed and compared. Their capabilities in SPC evaluation and imaging are explored through simulations and experiments. The optimal position for deployment of the magnetic field sensor is determined by scrutinizing the field uniformity and inspection sensitivity to SPC based on finite element simulations. After the optimal probe structure is chosen, quantitative evaluation and imaging of SPC are investigated. Signal/image processing algorithms for SPC evaluation are proposed. Through simulations and experiments, it has been found that the T-shaped probe together with the proposed processing algorithms is advantageous and preferable for profile recognition and depth evaluation of SPC.

Research on Characteristics of Field Uniformity in Reverberation Chamber Using Two TX Antennas

2012 ◽  
Vol E95.B (7) ◽  
pp. 2386-2392
Author(s):  
Jung-Hoon KIM ◽  
Tae-Heon JANG ◽  
Sung-Kuk LIM ◽  
Songjun LEE ◽  
Sung-Il YANG
Keyword(s):  
Reverberation Chamber ◽  
Field Uniformity

The Field Uniformity Analysis in a Triangular Prism Reverberation Chamber with a QRD

2011 ◽  
Vol E94-B (1) ◽  
pp. 334-337 ◽  
Author(s):  
Jung-Hoon KIM ◽  
Hye-Kwang KIM ◽  
Eugene RHEE ◽  
Sung-Il YANG
Keyword(s):  
Triangular Prism ◽  
Reverberation Chamber ◽  
Field Uniformity
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