Abstract
Interference effects in the transmit $B_{1}^{+}$ field can severely degrade the image quality in high-field Magnetic Resonance Imaging (MRI). High-permittivity pads are increasingly used to counteract these effects, but designing such pads is not trivial. In this paper, we present an efficient solution methodology for this dielectric RF shimming problem. By exploiting the fact that dielectric pads form a low rank perturbation of a large-scale background model, we are able to efficiently compute $B_{1}^{+}$ fields that correspond to a wide range of different pad realizations. This allows us to efficiently design dielectric pads that eliminate the $B_{1}^{+}$ -interference effects of high-field MRI. We show that significant speed up factors can be achieved compared with traditional field simulation approaches and we validate our approach against measurements. Measured and simulated field responses are in good agreement with each other indicating that the proposed solution methodology enables us to efficiently analyze dielectric pads in realistic MRI measurement settings.
Original language | English |
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Pages (from-to) | 666-673 |
Number of pages | 8 |
Journal | IEEE Transactions on Medical Imaging |
Volume | 36 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2017 |
Keywords
- B⁺₁ fields
- dielectric shimming …
- high-permittivity pads
- magnetic resonance imaging
- Sherman–Morrison–Woodbury formula