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Sensitivity and uniformity improvement of phased array MR images using inductive coupling and RF detuning circuits

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Magnetic Resonance Materials in Physics, Biology and Medicine Aims and scope Submit manuscript

Abstract

Objective

To improve sensitivity and uniformity of MR images obtained using a phased array RF coil, an inductively coupled secondary resonator with RF detuning circuits at 300 MHz was designed.

Materials and methods

A secondary resonator having detuning circuits to turn off the resonator during the transmit mode was constructed. The secondary resonator was located at the opposite side of the four-channel phased array to improve sensitivity and uniformity of the acquired MR images. Numerical simulations along with phantom and in vivo experiments were conducted to evaluate the designed secondary resonator.

Results

The numerical simulation results of |B1+| in a transmit mode showed that magnetic field uniformity would be decreased with a secondary resonator having no detuning circuits because of unwanted interferences between the transmit birdcage coil and the secondary resonator. The standard deviation (SD) of |B1+| was decreased 57% with a secondary resonator containing detuning circuits. The sensitivity and uniformity of |B1−| in the receive mode using a four-channel phased array were improved with the secondary resonator. Phantom experiments using a uniform saline phantom had 20% improvement of the mean signal intensity and 50% decrease in the SD with the secondary resonator. Mice with excess adipose tissue were imaged to demonstrate the utility of the secondary resonator.

Conclusion

The designed secondary resonator having detuning circuits improved sensitivity and uniformity of mouse MR images acquired using the four-channel phased array.

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Acknowledgement

The authors thank Jade Dyson and Prajakta Varadkar for preparing the mice used in this study.

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Authors and Affiliations

  1. Division of Cellular and Gene Therapies (DCGT)/OTAT/CBER, Food and Drug Administration, Silver Spring, MD, 20993-0002, USA

    Bu S. Park & Brent McCright

  2. Division of Biomedical Physics (DBP)/OSEL/CDRH, Food and Drug Administration, Silver Spring, MD, 20993-0002, USA

    Sunder S. Rajan

Authors
  1. Bu S. Park
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  2. Sunder S. Rajan
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  3. Brent McCright
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Contributions

BSP: conceptualization, data curation, formal analysis, methodology, investigation, resources, validation, visualization, and writing; SSR: methodology, formal analysis, and resources; BM: conceptualization, investigation, project administration, and supervision.

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Correspondence to Bu S. Park.

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The authors declare that they have no conflict of interest.

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All procedures performed in studies were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

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Park, B.S., Rajan, S.S. & McCright, B. Sensitivity and uniformity improvement of phased array MR images using inductive coupling and RF detuning circuits. Magn Reson Mater Phy 33, 725–733 (2020). https://doi.org/10.1007/s10334-020-00827-7

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  • DOI: https://doi.org/10.1007/s10334-020-00827-7

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