An RF‐gated wireless power transfer system for wireless MRI receive arrays

Byron, Kelly; Robb, Fraser; Stang, Pascal; Vasanawala, Shreyas S.; Pauly, John M.; Scott, Greig

doi:10.1002/cmr.b.21360

Cited by 18 publications

(14 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A trade‐off between battery life and device size would need to be considered. Gated wireless power transfer could also be explored for a maintenance‐free solution, however, the power density may be reduced in this case.…”

Section: Discussionmentioning

confidence: 99%

Toward “plug and play” prospective motion correction for MRI by combining observations of the time varying gradient and static vector fields

Niekerk

Kouwe

Meintjes

2019

Magnetic Resonance in Med

View full text Add to dashboard Cite

Purpose The efficacy of a Wireless Radio frequency triggered Acquisition Device (WRAD) is evaluated for high frequency (50 Hz) prospective motion correction in a 3‐dimensional spoiled gradient echo pulse sequence. Methods The device measures the rate of change in the gradient vector fields (slew) using a 3‐dimensional assembly of Printed Circuit Board (PCB) inductors and the direction of the static magnetic field using a 3‐axis Hall effect magnetometer. The slew vector encoding is highly efficient, because the Maxwell‐term position encoding is observable, allowing overconstrained pose measurement using 3 sinusoidal gradient pulses lasting 880 μs. Since small offsets in the magnetometer can introduce bias into the pose estimates, sensor/system biases are tracked using a lightweight Kalman filter. The only calibration required is determining a geometric scaling factor for the pickup coils, which is specific to the device and will therefore be valid in any scanner. Results The device was used to perform prospective motion correction in 3 subjects, resulting in an increase in Average Edge Strength (AES) for involuntary and deliberate motion. Conclusions The WRAD is simple to set up and use, with well‐defined measurement variance. This could enable “plug and play” prospective motion correction if pulse sequence independence is achieved.

show abstract

Section: Discussionmentioning

confidence: 99%

Toward “plug and play” prospective motion correction for MRI by combining observations of the time varying gradient and static vector fields

Niekerk

Kouwe

Meintjes

2019

Magnetic Resonance in Med

View full text Add to dashboard Cite

show abstract

“…RF WPT implies the construction of a dedicated system consisting of primary (e.g., in the patient table) and secondary (close to the receive coil) loops for the sole purpose of power delivery by inductive coupling. Byron et al [78,79] propose an MRcompatible WPT system operating at 10 MHz transferring up to 13 W over a few centimeters' distance in a 1.5 T system.…”

Section: Wireless Power Transfermentioning

confidence: 99%

Perspectives in Wireless Radio Frequency Coil Development for Magnetic Resonance Imaging

et al. 2020

View full text Add to dashboard Cite

This paper addresses the scientific and technological challenges related to the development of wireless radio frequency (RF) coils for magnetic resonance imaging (MRI) based on published literature together with the authors' interpretation and further considerations. Key requirements and possible strategies for the wireless implementation of three important subsystems, namely the MR receive signal chain, control signaling, and on-coil power supply, are presented and discussed. For RF signals of modern MRI setups (e.g., 3 T, 64 RF receive channels), with on-coil digitization and advanced methods for dynamic range (DR ≥ 16-bit) and data rate compression, still data rates > 500 Mbps will be required. For wireless high-speed MR data transmission, 60 GHz WiGig and optical wireless communication appear to be suitable strategies; however, on-coil functionality during MRI scans remains to be verified. Besides RF signals, control signals for on-coil components, e.g., active detuning, synchronization to the MR system, and B 0 shimming, have to be managed. Wireless power supply becomes an important issue, especially with a large amount of additional on-coil components. Wireless power transfer systems (>10 W) seem to be an attractive solution compared to bulky MR-compatible batteries and energy harvesting with low power output. In our opinion, completely wireless RF coils will ultimately become feasible in the future by combining efficient available strategies from recent scientific advances and novel research. Besides ongoing improvement of all three subsystems, innovations are specifically required regarding wireless technologies, MR compatibility, and wireless power supply.

show abstract

“…The link efficiency (η link ) takes into consideration only the coil losses and loading. The total system efficiency: (8) includes the efficiency of the power amplifier, matching network and rectification. Implicit is the interaction between stages.…”

Section: Wireless Power Transfer Efficiencymentioning

confidence: 99%

“…However, the ISM band at 6.78 MHz is unsuitable for continuous WPT in MRI. We previously chose 10 MHz [8], because harmonics generated by the WPT system at intervals of 10 MHz will bracket the MRI bands of both 1.5T (64 MHz) and 3T (128 MHz) scanners. A Crystek crystal oscillator is presently used, but 10 MHz conveniently allows synchronous locking to the scanner frequency reference.…”

Section: A Frequency Choicementioning

confidence: 99%

An MRI Compatible RF MEMs Controlled Wireless Power Transfer System

Byron

Winkler

Robb

et al. 2019

IEEE Trans. Microwave Theory Techn.

Self Cite

View full text Add to dashboard Cite

In magnetic resonance imaging (MRI), wearable wireless receive coil arrays are a key technology goal. An MRI compatible wireless power transfer (WPT) system will be needed to realize this technology. An MRI WPT system must withstand the extreme electromagnetic environment of the scanner and cannot degrade MRI image quality. Here, a WPT system is developed for operation in MRI scanners using new microelectromechanical RF switch (RF MEMs) technology. The WPT system includes a class-E power amplifier, RF MEMs automated impedance matching, a primary coil array employing RF MEMs power steering, and a flexible secondary coil with class E rectification. To adapt WPT technology to MRI, techniques are developed for operation at high magnetic field, and to mitigate the RF interactions between the scanner and WPT system. A major challenge was the identification and suppression of noise and harmonic interference, by gating, filtering, and rectifier topologies. The system can achieve 63% efficiency while exceeding 13 W delivery over a coil distance of 3.5 cm. For continuous WPT beyond 5W, added filters and fullwave class E rectification lowers harmonic generation at some cost to efficiency, while image SNR reaches about 32% of the ideal. RF-gated WPT, which interrupts power transfer in the MRI signal acquisition interval, achieves SNR performance to within 1 dB of the ideal. With further refinement, the inclusion of WPT technology in MRI scanners appears completely feasible.

show abstract

An RF‐gated wireless power transfer system for wireless MRI receive arrays

Cited by 18 publications

References 33 publications

Toward “plug and play” prospective motion correction for MRI by combining observations of the time varying gradient and static vector fields

Toward “plug and play” prospective motion correction for MRI by combining observations of the time varying gradient and static vector fields

Perspectives in Wireless Radio Frequency Coil Development for Magnetic Resonance Imaging

An MRI Compatible RF MEMs Controlled Wireless Power Transfer System

Contact Info

Product

Resources

About