Aperture–patch sandwich metasurface for magnetic field enhancement in 1.5 T MRI

Das, Priyanka; Gupta, Jegyasu; Sikdar, Debabrata; Bhattacharjee, Ratnajit

doi:10.1016/j.mri.2023.03.005

Cited by 7 publications

(2 citation statements)

References 29 publications

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“…The results shown in the present work are comparable to these previous results with the primary difference being lack of a high‐permittivity material substrate and the anatomical region being imaged. However, in the context of the broader literature, most metasurface development has been focused on image enhancement at 1.5 T 22,24,27 and 3 T 21,23 . Furthermore, there has also been work that has focused on exclusively enhancing the receive field (

{\mathrm{B}}_1^{-}

) rather than the transmit field, in contrast to what was done here 26,37 .…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have shown several in vivo implementations of this technology, including wrist 22,26 and head imaging 27 at 1.5 T as well as abdominal imaging at 3 T 21 . However, the metasurfaces designs described in those previous studies were focused on in vivo applications at field strengths below 7 T. Many promising 7 T studies have been previously performed based on electromagnetic (EM) simulations or phantom experiments 28,29 .…”

Section: Introductionmentioning

confidence: 99%

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In vivo B1+ enhancement of calf MRI at 7 T via optimized flexible metasurfaces

Jacobs,

Wilson,

Brink

et al. 2024

Magnetic Resonance in Med

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PurposeUltrahigh field (≥7 T) MRI is at the cutting edge of medical imaging, enabling enhanced spatial and spectral resolution as well as enhanced susceptibility contrast. However, transmit () field inhomogeneity due to standing wave effects caused by the shortened RF wavelengths at 7 T is still a challenge to overcome. Novel hardware methods such as dielectric pads have been shown to improve the field inhomogeneity but are currently limited in their corrective effect by the range of high‐permittivity materials available and have a fixed shelf life. In this work, an optimized metasurface design is presented that demonstrates in vivo enhancement of the field.MethodsA prototype metasurface was optimized by an empirical capacitor sweep and by varying the period size. Phantom temperature experiments were performed to evaluate potential metasurface heating effects during scanning. Lastly, in vivo gradient echo images and maps were acquired on five healthy subjects on a 7 T system. Dielectric pads were also used as a comparison throughout the work as a standard comparison.ResultsThe metasurfaces presented here enhanced the average relative SNR of the gradient echo images by a factor of 2.26 compared to the dielectric pads factor of 1.61. Average values reflected a similar enhancement of 27.6% with the metasurfaces present versus 8.9% with the dielectric pads.ConclusionThe results demonstrate that metasurfaces provide superior performance to dielectric padding as shown by maps reflecting their direct effects and resulting enhancements in image SNR at 7 T.

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