This paper presents an investigation of methods for improving homogeneity inside various dielectric phantoms situated in a 10.5-T human-sized magnetic resonance imaging. The transmit B1 (B+ 1 ) field is excited with a quadrature-fed circular patch probe and a 12-element capacitively loaded microstrip array. Both simulations and measurements show improved homogeneity in a cylindrical water phantom, an inhomogeneous phantom (pineapple), and a NIST standard phantom. The simulations are performed using a full-wave finite-difference time-domain solver (Sim4Life) in order to find the B+ 1 field distribution and compared to the gradient-recalled echo image and efficiency result. For additional field uniformity, the wall electromagnetic boundary conditions are modified with a passive quadrifilar helix. Finally, these methods are applied in simulation to head imaging of an anatomically correct human body model (Duke, IT'IS Virtual Population) showing improved homogeneity and specific absorption rate for various excitations.
|Original language||English (US)|
|Number of pages||13|
|Journal||IEEE Transactions on Microwave Theory and Techniques|
|State||Published - Mar 2019|
Bibliographical noteFunding Information:
Manuscript received August 6, 2018; revised October 26, 2018; accepted November 4, 2018. Date of publication December 14, 2018; date of current version March 5, 2019. This work was supported in part by the National Science Foundation under a Collaborative Research Grant ECCS 1307614 at the University of Colorado, Boulder, and in part by the National Institutes of Health under Grant P41 EB015894 and Grant S10 RR029672. (Corresponding author: Patrick Bluem.) P. Bluem and Z. Popović are with the Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, CO 80309-0425 USA (e-mail: firstname.lastname@example.org; email@example.com).
© 1963-2012 IEEE.
- Finite-difference time domain (FDTD)
- magnetic resonance imaging (MRI)
- patch antenna
PubMed: MeSH publication types
- Journal Article