Eight channel transmit array volume coil using on-coil radiofrequency current sources
Krishna N Kurpad1, Eddy B Boskamp1, Steven M Wright1
11 Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843, USA ; 2 Department of Radiology, University of Wisconsin, Madison, WI 53705, USA ; 3 Applied Science Laboratory, GE Healthcare, Waukesha, WI 53188, USA ; 4 Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA ; 5 Department of Radiology, Texas A&M Health Sciences Center, Bryan, TX 77807, USA.
Background:
At imaging frequencies associated with high-field MRI, the combined effects of increased load-coil interaction and shortened wavelength results in degradation of circular polarization and B1 field homogeneity in the imaging volume. Radio frequency (RF) shimming is known to mitigate the problem of B1 field inhomogeneity. Transmit arrays with well decoupled transmitting elements enable accurate B1 field pattern control using simple, non-iterative algorithms.
Methods:
An eight channel transmit array was constructed. Each channel consisted of a transmitting element driven by a dedicated on-coil RF current source. The coil current distributions of characteristic transverse electromagnetic (TEM) coil resonant modes were non-iteratively set up on each transmitting element and 3T MRI images of a mineral oil phantom were obtained.
Results:
B1 field patterns of several linear and quadrature TEM coil resonant modes that typically occur at different resonant frequencies were replicated at 128 MHz without having to retune the transmit array. The generated B1 field patterns agreed well with simulation in most cases.
Conclusions:
Independent control of current amplitude and phase on each transmitting element was demonstrated. The transmit array with on-coil RF current sources enables B1 field shimming in a simple and predictable manner.
More Related Videos
10:22MRM Microcoil Performance Calibration and Usage Demonstrated on Medicago truncatula Roots at 22 T
Published on: January 16, 2021
10:52Design, Instrumentation and Usage Protocols for Distributed In Situ Thermal Hot Spots Monitoring in Electric Coils using FBG Sensor Multiplexing
Published on: March 8, 2020
Related Concept Videos
01:18Magnetic Field Due to Two Straight Wires
01:16Magnetic Field Of A Current Loop
01:10Generating Electromagnetic Radiations
01:25Multiple Voltage Sources
In series, the positive terminal of one battery is connected to the negative terminal of another battery. Hence, the voltage of each battery is added to give the net voltage, which is increased because each battery boosts the electrons that enter it. The same current flows through each battery because they are connected in series.
Batteries are...
01:13Torque On A Current Loop In A Magnetic Field
Consider a rectangular current-carrying loop containing N turns of wire, placed in a uniform magnetic field. The net force on a current-carrying loop...
01:17Force On A Current Loop In A Magnetic Field