Electromagnetic simulation of a 16-channel head transceiver at 7 T using circuit-spatial optimization.
Magn Reson Med
; 85(6): 3463-3478, 2021 06.
Article
en En
| MEDLINE
| ID: mdl-33533500
ABSTRACT
PURPOSE:
With increased interest in parallel transmission in ultrahigh-field MRI, methods are needed to correctly calculate the S-parameters and complex field maps of the parallel transmission coil. We present S-parameters paired with spatial field optimization to fully simulate a double-row 16-element transceiver array for brain MRI at 7 T.METHODS:
We implemented a closed-form equation of the coil S-parameters and overall spatial B1+ field. We minimized a cost function, consisting of coil S-parameters and the B1+ homogeneity in brain tissue, by optimizing transceiver components, including matching, decoupling circuits, and lumped capacitors. With this, we are able to compare the in silico results determined with and without B1+ homogeneity weighting. Using the known voltage range from the host console, we reconstructed the B1+ maps of the array and performed RF shimming with four realistic head models.RESULTS:
As performed with B1+ homogeneity weighting, the optimized coil circuit components were highly consistent over the four heads, producing well-tuned, matched, and decoupled coils. The mean peak forward powers and B1+ statistics for the head models are consistent with in vivo human results (N = 8). There are systematic differences in the transceiver components as optimized with or without B1+ homogeneity weighting, resulting in an improvement of 28.4 ± 7.5% in B1+ homogeneity with a small 1.9 ± 1.5% decline in power efficiency.CONCLUSION:
This co-simulation methodology accurately simulates the transceiver, predicting consistent S-parameters, component values, and B1+ field. The RF shimming of the calculated field maps match the in vivo performance.Palabras clave
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Imagen por Resonancia Magnética
Tipo de estudio:
Prognostic_studies
Límite:
Humans
Idioma:
En
Revista:
Magn Reson Med
Asunto de la revista:
DIAGNOSTICO POR IMAGEM
Año:
2021
Tipo del documento:
Article
País de afiliación:
Estados Unidos