A smart switching system to enable automatic tuning and detuning of metamaterial resonators in MRI scans

Scientific Reports, vol. 10, pp. 10042

Abstract

We present a radio-frequency-activated switching system that can automatically detune a metamaterial resonator to enhance magnetic resonance imaging (MRI) performance. Local sensitivity-enhancing metamaterials typically consist of resonant components, which means that the transmitted radio frequency field is spatially inhomogeneous. The switching system shows for the first time that a metamaterial resonator can be detuned during transmission and tuned during reception using a digital circuit. This allows a resonating system to maintain homogeneous transmit field while maintaining an increased receive sensitivity. As a result, sensitivity can be enhanced without changing the system-provided specific absorption rate (SAR) models. The developed digital circuit consists of inductors sensitive to the transmit radio-frequency pulses, along with diodes acting as switches to control the resonance frequency of the resonator. We first test the automatic resonator detuning on-the-bench, and subsequently evaluate it in a 1.5 T MRI scanner using tissue-mimicking phantoms. The scan results demonstrate that the switching mechanism automatically detunes the resonator in transmit mode, while retaining its sensitivity-enhancing properties (tuned to the Larmor frequency) in receive mode. Since it does not require any connection to the MRI console, the switching system can have broad applications and could be adapted for use with other types of MRI scanners and field-enhancing resonators.

Authors 10

1. Shimul C. Saha corresponding

   MediWiSe (United Kingdom)

   Affiliation as printed

   MediWiSe| Medical Wireless Sensing Ltd, Queen Mary Bio Enterprise Innovation Centre, 42 New Road, E1 2AX, London, UK. shimul.saha@metamaterial.com

   Metamaterial Inc, 1 Research Drive, Dartmouth, Nova Scotia, B2Y 4M9, Canada. shimul.saha@metamaterial.com

   MediWiSe| Medical Wireless Sensing Ltd, Queen Mary Bio Enterprise Innovation Centre, 42 New Road, E1 2AX, London, UK

   Metamaterial Inc, 1 Research Drive, Dartmouth, Nova Scotia, B2Y 4M9, Canada

2. Roberto L. Pricci

   MediWiSe (United Kingdom)

   Affiliation as printed

   MediWiSe| Medical Wireless Sensing Ltd, Queen Mary Bio Enterprise Innovation Centre, 42 New Road, E1 2AX, London, UK

   Metamaterial Inc, 1 Research Drive, Dartmouth, Nova Scotia, B2Y 4M9, Canada

3. Μαρία Κουτσουπίδου

   King's College London · MediWiSe (United Kingdom)

   Affiliation as printed

   Department of Engineering, King's College London, London, WC2R 2LS, UK

   MediWiSe| Medical Wireless Sensing Ltd, Queen Mary Bio Enterprise Innovation Centre, 42 New Road, E1 2AX, London, UK

4. Helena Cano-Garcia

   MediWiSe (United Kingdom)

   Affiliation as printed

   MediWiSe| Medical Wireless Sensing Ltd, Queen Mary Bio Enterprise Innovation Centre, 42 New Road, E1 2AX, London, UK

   Metamaterial Inc, 1 Research Drive, Dartmouth, Nova Scotia, B2Y 4M9, Canada

5. Ditjon Katana

   MediWiSe (United Kingdom)

   Affiliation as printed

   MediWiSe| Medical Wireless Sensing Ltd, Queen Mary Bio Enterprise Innovation Centre, 42 New Road, E1 2AX, London, UK

6. Srinivas Rana

   King's College London

   Affiliation as printed

   Department of Engineering, King's College London, London, WC2R 2LS, UK

7. Panagiotis Kosmas

   King's College London · MediWiSe (United Kingdom)

   Affiliation as printed

   Department of Engineering, King's College London, London, WC2R 2LS, UK

   MediWiSe| Medical Wireless Sensing Ltd, Queen Mary Bio Enterprise Innovation Centre, 42 New Road, E1 2AX, London, UK

   Metamaterial Inc, 1 Research Drive, Dartmouth, Nova Scotia, B2Y 4M9, Canada

8. George K. Palikaras

   MediWiSe (United Kingdom)

   Affiliation as printed

   MediWiSe| Medical Wireless Sensing Ltd, Queen Mary Bio Enterprise Innovation Centre, 42 New Road, E1 2AX, London, UK

   Metamaterial Inc, 1 Research Drive, Dartmouth, Nova Scotia, B2Y 4M9, Canada

9. ANDREW G. WEBB Aachen C.J. Gorter High Field Magnetic Resonance Center

   Leiden University Medical Center

   Affiliation as printed

   C.J. Gorter High Field Magnetic Resonance Center, Leiden University Medical Center, Albinusdreef 2, 2333, ZA, Leiden, The Netherlands

10. Efthymios Kallos

    MediWiSe (United Kingdom)

    Affiliation as printed

    MediWiSe| Medical Wireless Sensing Ltd, Queen Mary Bio Enterprise Innovation Centre, 42 New Road, E1 2AX, London, UK

    Metamaterial Inc, 1 Research Drive, Dartmouth, Nova Scotia, B2Y 4M9, Canada