High-Permittivity Pad Design for Dielectric Shimming in Magnetic Resonance Imaging Using Projection-Based Model Reduction and a Nonlinear Optimization Scheme

High-Permittivity Pad Design for Dielectric Shimming in Magnetic Resonance Imaging Using Projection-Based Model Reduction and a Nonlinear Optimization Scheme

van Gemert, J.H.F. (TU Delft Microwave Sensing, Signals & Systems)
Brink, W.M. (Leiden University Medical Center)
Webb, A. (Leiden University Medical Center)
Remis, R.F. (TU Delft Signal Processing Systems)

2018

Inhomogeneities in the transmit radio frequency magnetic field ( {\text{B}}-{1}^{+} ) reduce the quality of magnetic resonance (MR) images. This quality can be improved by using high-permittivity pads that tailor the {\text{B}}-{1}^{+} fields. The design of an optimal pad is application-specific and not straightforward and would therefore benefit from a systematic optimization approach. In this paper, we propose such a method to efficiently design dielectric pads. To this end, a projection-based model order reduction technique is used that significantly decreases the dimension of the design problem. Subsequently, the resulting reduced-order model is incorporated in an optimization method in which a desired field in a region of interest can be set. The method is validated by designing a pad for imaging the cerebellum at 7 T. The optimal pad that is found is used in an MR measurement to demonstrate its effectiveness in improving the image quality.

dielectric shimming
fields
high-permittivity pads
Magnetic resonance imaging
optimization
reduced order modeling

http://resolver.tudelft.nl/uuid:f10d191c-6258-4d63-ab77-2ff9fe86c516

https://doi.org/10.1109/TMI.2018.2791179

0278-0062

IEEE Transactions on Medical Imaging, 37 (4), 1035-1044

Accepted author manuscript

Institutional Repository

journal article

© 2018 J.H.F. van Gemert, W.M. Brink, A. Webb, R.F. Remis