Active optical-based detuning circuit for receiver endoluminal coil

Saniour, Isabelle; Aydé, R.; Perrier, Anne-Laure; Gaborit, Gwenaël; Duvillaret, Lionel; Sablong, Raphaël; Beuf, Olivier

doi:10.1088/2057-1976/aa5db0

Cited by 5 publications

(7 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The increased delays by adding such driver circuit is also demonstrated in a recent work [44] using a PIN diode driver for high-power pulses where the rise-time is close to 1 µs and the fall-time increases to 7.4 µs, which are comparable to the results obtained with controlled MEMSs. Delays are nevertheless of the same order as optical-based decoupling circuits with 13.6 µs and 1.7 µs for tuning and detuning, respectively [23], which proved to be effective. In any case, MEMS switching delays are still small and compliant with most MR clinical applications where the RF pulse duration of imaging sequences as well as signal readout time [33] are of the order of milliseconds.…”

Section: Discussionmentioning

confidence: 91%

“…It is particularly relevant in multinuclear MR coils. Other methods based on optical components have been proposed in the literature mainly founded on photoelectronic devices such as the photoresistor [20], photodiode [21], [22], combined photodiodes and a PIN diode [23], PhotoMOS [24], or MOSFET with optically isolated [25] devices. The optical decoupling solutions have the advantage of using nongalvanic transmission means thereby avoiding induced current in the shield and increasing patient safety [26].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Serial and Parallel Active Decoupling Characterization Using RF MEMS Switches for Receiver Endoluminal Coils at 1.5 T

Raki¹,

Koon²,

Saniour³

et al. 2020

IEEE Sensors J.

View full text Add to dashboard Cite

MEMS (Micro Electro Mechanical System) switches were assessed and compared to PIN diode in fulfilling the task of active decoupling of Receiver Endoluminal Coils (RECs). Three prototype RECs with the PIN diode in parallel (pPIN), MEMS in parallel (pMEMS) and MEMS in series (sMEMS) with the REC loop were built. Quality factors (Q-values), decoupling efficiency and switching delays were characterized on bench and Signal-to-Noise Ratios (SNRs) established on images at 1.5 T. Q-values were equal to 62.5, 41.2 and 65.1 for pPIN, sMEMS and pMEMS, respectively. In the decoupled state, reflection coefficients S11 and S21 at resonance frequency both indicated proper decoupling. Switching delays were less than 0.7 µs and 10 µs for pPIN and MEMS RECs, respectively. Decoupling/coupling delays of MEMS remained compatible with most Magnetic Resonance (MR) clinical applications. For all prototypes, MR images displayed no signal saturation and similar elliptical image sensitivity patterns. No artifacts due to active decoupling failure were observed. Mean SNR values obtained with pMEMS REC were higher than those obtained with sMEMS REC but lower than with pPIN REC because of the use of additional instrumentation to render the scanner compatible with the MEMS utilization. MEMS in parallel are an interesting alternative to PIN diode for decoupling and could lead to better SNR with a compatible MR system (dedicated control signal). The MEMS in series can be used for both decoupling and reconfiguration of the REC loop geometry for colon wall examination.

show abstract

Section: Discussionmentioning

confidence: 91%

mentioning

confidence: 99%

Serial and Parallel Active Decoupling Characterization Using RF MEMS Switches for Receiver Endoluminal Coils at 1.5 T

Raki¹,

Koon²,

Saniour³

et al. 2020

IEEE Sensors J.

View full text Add to dashboard Cite

show abstract

“…The strategy of incorporating several RF traps in the galvanic connection between the coil and the scanner is not the only one that can be adopted to reduce the electric field artifact, and some ongoing studies have assessed the feasibility of an optical connection both for the NMR signal received and for the active optical decoupling of the reception coil. This strategy would directly suppress the electric field artifacts, but at the cost of greater design complexity 27,28 …”

Section: Discussionmentioning

confidence: 99%

Feasibility and characterization of a safe susceptibility‐matched endorectal coil for MR spectroscopy

et al. 2020

View full text Add to dashboard Cite

When using endorectal coils, local radiofrequency (RF) heating may occur in the surrounding tissue. Furthermore, most endorectal coils create a susceptibility artifact detrimental to both anatomical magnetic resonance imaging (MRI) and spectroscopy (MRS) acquisitions. We aimed at assessing the safety and MRS performance of a susceptibility-matched endorectal coil for further rectal wall analysis. Experiments were performed on a General Electric MR750 3 T scanner. A variable number of miniaturized passive RF traps were incorporated in the reception cable. The assessment of RF heating and coil sensitivity was conducted on a 1.5% agar-agar phantom doped with NaCl. Several susceptibility-matched materials such as Ultem, perfluorocarbon and barium sulfate were then compared with an external coil. Finally, Ultem was used as a solid support for an endorectal coil and compared with a reference coil. Phantom experiments exhibited a complete suppression of both the RF heating phenomenon and the coil sensitivity artifact. Ultem was the material that produced the smallest image distortion. The full width at half maximum of MR spectra acquired using the susceptibility-matched endorectal coil showed at least 30% narrowing compared with a reference endorectal coil. A susceptibility-matched endorectal coil with RF traps incorporated was validated on phantoms. This coil appears to be a promising device for future in vivo experiments.

show abstract

“…This technique has worked well for small amounts of power (tens to hundreds of milliwatts) [21] but it becomes troublesome for larger values. It was successfully implemented to detune receive coils, for instance [22]. Electromagnetic induction: the physical principle is the same as in transformers, where the magnetic flux is used to transport the energy from a primary to a secondary coil.…”

Section: Wireless Power Supplymentioning

confidence: 99%

Optical Link as an Alternative for MRI Receive Coils: Toward a Passive Approach

Nobre

Gaborit

Sablong

et al. 2023

IEEE Trans. Biomed. Eng.

View full text Add to dashboard Cite

Objective: The objective of this work was to propose an alternative solution to NMR signal transmission by replacing the coaxial cables of the receiver radiofrequency (RF) coil in the context of MRI so as to improve safety. Starting from the analysis of previous studies and reports on the topic, the difficulty of supplying power wirelessly to an RF coil was identified. To avoid this difficult task, the development of a passive analog optical link was studied. Methods: In order to quantify the requirements for achieving an analog conversion, the performance of the link was evaluated based on the input NMR signal amplitude and the optical power and compared with that of a galvanic link. Acquisitions were performed on a 7-T preclinical MRI system with a doped saline solution as phantom. A passive and MRI-compatible polarization-state custommade modulator was tested as well as a commercial Mach-Zehnder interferometer. Results: The conversion was not sensitive enough to keep similar SNRs, but the main source of noise was identified along with parameters for improvement. Optical power emitted by the laser, insertion loss, and full-phase inversion voltage of the modulators were found to be crucial characteristics for the application. These data indicate that custom application devices are required since the frequency, bandwidth, and amplitude of NMR signals are quite different to usual telecommunication signals. Conclusion: An electro-optic modulation and a transmission channel were successfully conceived and tested. Images were reconstructed with some significant SNR drawbacks that are expected to be compensated with an appropriate modulator. Significance: While technical challenges remain, our approach to a two-decades-long problem could solve a major issue of MRI safety by removing the need for supplying on-coil electrical current.

show abstract

Active optical-based detuning circuit for receiver endoluminal coil

Cited by 5 publications

References 28 publications

Serial and Parallel Active Decoupling Characterization Using RF MEMS Switches for Receiver Endoluminal Coils at 1.5 T

Serial and Parallel Active Decoupling Characterization Using RF MEMS Switches for Receiver Endoluminal Coils at 1.5 T

Feasibility and characterization of a safe susceptibility‐matched endorectal coil for MR spectroscopy

Optical Link as an Alternative for MRI Receive Coils: Toward a Passive Approach

Contact Info

Product

Resources

About