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Vector modulator based active compensation of direct feedthrough
(Infinite Science Publishing, 2020)
In magnetic particle imaging (MPI), simultaneous excitation and signal acquisition leads to direct feedthrough problems. While this direct-feedthrough can be mitigated up to some extent with passive compensation, this may ...
MR safety watchdog for active catheters: wireless impedance control with real‐time feedback
(Wiley, 2020)
Purpose: To dynamically minimize radiofrequency (RF)‐induced heating of an active catheter through an automatic change of the termination impedance. Methods: A prototype wireless module was designed that modifies the input ...
In vivo human head MRI at 10.5T: a radiofrequency safety study and preliminary imaging results
(Wiley, 2020)
Purpose: The purpose of this study is to safely acquire the first human head images at 10.5T. Methods: To ensure safety of subjects, we validated the electromagnetic simulation model of our coil. We obtained quantitative ...
Improving radiofrequency power and specific absorption rate management with bumped transmit elements in ultra-high field MRI
(Wiley, 2020)
Purpose: In this study, we investigate a strategy to reduce the local specific absorption rate (SAR) while keeping constant inside the region of interest (ROI) at the ultra‐high field (B0 ≥ 7T) MRI. Methods: Locally ...
Wireless control of induced radiofrequency currents in active implantable medical devices during MRI
(International Society for Magnetic Resonance in Medicine, 2020)
Purpose
To introduce a prototype active implantable medical device (AIMD) for which the induced radiofrequency currents can be controlled wirelessly.
Methods
The modified transmission line method is used to formulate ...
RF heating of deep brain stimulation implants in open-bore vertical MRI systems: a simulation study with realistic device configurations
(International Society for Magnetic Resonance in Medicine, 2020)
Purpose
Patients with deep brain stimulation (DBS) implants benefit highly from MRI, however, access to MRI is restricted for these patients because of safety hazards associated with RF heating of the implant. To date, ...
Eigenmode analysis of the scattering matrix for the design of MRI transmit array coils
(International Society for Magnetic Resonance in Medicine, 2021)
To obtain efficient operation modes of transmit array (TxArray) coils using a general design technique based on the eigenmode analysis of the scattering matrix.
Methods
We introduce the concept of modal reflected power ...
Accelerating the co-simulation method for the design of transmit array coils for MRI
(Springer, 2020)
Objective: Accelerating the co-simulation method for the design of transmit array (TxArray) coils is studied using equivalent circuit models. Materials and methods: Although the co-simulation method dramatically reduces ...
SNR weighting for shear wave speed reconstruction in tomoelastography
(John Wiley & Sons Ltd., 2020-08-06)
In tomoelastography, to achieve a final wave speed map by combining reconstructions obtained from all spatial directions and excitation frequencies, the use of weights is inevitable. Here, a new weighting scheme, which ...
A nine-channel transmit/receive array for spine imaging at 10.5 T: Introduction to a nonuniform dielectric substrate antenna
(John Wiley & Sons, Inc., 2021-11-05)
Purpose: The purpose of this study is to introduce a new antenna element with improved transmit performance, named the nonuniform dielectric substrate(NODES) antenna, for building transmit arrays at ultrahigh- field.Methods: ...