Design and construction of a novel 1 H/ 19 F double-tuned coil system using PIN-diode switches at 9.4 T

Choi, C.; Hong, Seok-In; Ha, Yonghyun; Shah, N. Jon

doi:10.1016/j.jmr.2017.04.005

Cited by 21 publications

(58 citation statements)

References 27 publications

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“…There was only a 4.5% difference (10.6–11.1

μ T / \sqrt{kW}

) in the mean transmit efficiency measured with the three switching configurations, which is likely in part due to the variation in re‐positioning the phantom. This is in accordance with other studies, which showed similar imaging performance with switched dual‐tuned coils when compared with single‐tuned counterparts . Therefore, we believe the choice of switching method is primarily one of practicality and we summarize below the salient considerations.…”

Section: Discussionsupporting

confidence: 88%

“…This is in accordance with other studies, which showed similar imaging performance with switched dual-tuned coils when compared with single-tuned counterparts. 12,23 Therefore, we believe the choice of switching method is primarily one of practicality and we summarize below the salient considerations.…”

Section: Discussionmentioning

confidence: 99%

“…

Q \sim

120 at 128 MHz in Maunder et al), which results in negligible additional loss. For example, when comparing a dual‐tuned coil design to single tuned counterparts, SNR losses of 25% and 50% were reported for 19 F and 1 H, respectively, while the switching used in Choi et al resulted in more equivalent performance for imaging both 19 F and 1 H when compared with respective single tuned coils. Therefore, due to the close frequencies of 19 F and 1 H at 1.5 T the use of switching is favored.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of MEMS switches and PIN diodes for switched dual tuned RF coils

Maunder

Rao

Robb

et al. 2018

Magnetic Resonance in Med

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PurposeTo evaluate the performance of micro‐electromechanical systems (MEMS) switches against PIN diodes for switching a dual‐tuned RF coil between 19F and 1H resonant frequencies for multi‐nuclear lung imaging.MethodsA four‐element fixed‐phase and amplitude transmit–receive RF coil was constructed to provide homogeneous excitation across the lungs, and to serve as a test system for various switching methods. The MR imaging and RF performance of the coil when switched between the 19F and 1H frequencies using MEMS switches, PIN diodes and hardwired configurations were compared.ResultsThe performance of the coil with MEMS or PIN diode switching was comparable in terms of RF measurements, transmit efficiency and image SNR on both 19F and 1H nuclei. When the coil was not switched to the resonance frequency of the respective nucleus being imaged, reductions in the transmit efficiency were observed of 32% at the 19F frequency and 12% at the 1H frequency. The coil provides transmit field homogeneity of ±12.9% at the 1H frequency and ±14.4% at the 19F frequency in phantoms representing the thorax with the air space of the lungs filled with perfluoropropane gas.ConclusionMEMS and PIN diodes were found to provide comparable performance in on‐state configuration, while MEMS were more robust in off‐state high‐powered operation (>1 kW), providing higher isolation and requiring a lower DC switching voltage than is needed for reverse biasing of PIN diodes. In addition, clear benefits of switching between the 19F and 1H resonances were demonstrated, despite the proximity of their Larmor frequencies.

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“…There was only a 4.5% difference (10.6–11.1

μ T / \sqrt{kW}

Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

“…

Q \sim

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Comparison of MEMS switches and PIN diodes for switched dual tuned RF coils

Maunder

Rao

Robb

et al. 2018

Magnetic Resonance in Med

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“…The results are based on the previous MR development of a sophisticated RF system which included the RF coils and interface essential for performing multinuclear MR experiments [ 28 ]. The development of this system was particularly challenging, as increasing the number of available nuclei in the MR setup is likely to result in substantial SNR loss and degradation of image quality [ 38 – 40 ] if the utmost care is not taken. When comparing the performance of a double- or triple-tuned coil, single-tuned coils are always used as reference coils.…”

Section: Discussionmentioning

confidence: 99%

An in vivo multimodal feasibility study in a rat brain tumour model using flexible multinuclear MR and PET systems

et al. 2020

Self Cite

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Background: In addition to the structural information afforded by 1 H MRI, the use of X-nuclei, such as sodium-23 (23 Na) or phosphorus-31 (31 P), offers important complementary information concerning physiological and biochemical parameters. By then combining this technique with PET, which provides valuable insight into a wide range of metabolic and molecular processes by using of a variety of radioactive tracers, the scope of medical imaging and diagnostics can be significantly increased. While the use of multimodal imaging is undoubtedly advantageous, identifying the optimal combination of these parameters to diagnose a specific dysfunction is very important and is advanced by the use of sophisticated imaging techniques in specific animal models. Methods: In this pilot study, rats with intracerebral 9L gliosarcomas were used to explore a combination of sequential multinuclear MRI using a sophisticated switchable coil set in a small animal 9.4 T MRI scanner and, subsequently, a small animal PET with the tumour tracer O-(2-[ 18 F]-fluoroethyl)-L-tyrosine ([ 18 F]FET). This made it possible for in vivo multinuclear MR-PET experiments to be conducted without compromising the performance of either multinuclear MR or PET. Results: High-quality in vivo images and spectra including high-resolution 1 H imaging, 23 Na-weighted imaging, detection of 31 P metabolites and [ 18 F]FET uptake were obtained, allowing the characterisation of tumour tissues in comparison to a healthy brain. It has been reported in the literature that these parameters are useful in the identification of the genetic profile of gliomas, particularly concerning the mutation of the isocitrate hydrogenase gene, which is highly relevant for treatment strategy. Conclusions: The combination of multinuclear MR and PET in, for example, brain tumour models with specific genetic mutations will enable the physiological background of signal alterations to be explored and the identification of the optimal combination of imaging parameters for the non-invasive characterisation of the molecular profile of tumours.

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“…The results were based on the previous MR development of a sophisticated RF system which included the RF coils and interface essential for performing multinuclear MR experiments [28]. The development of this system was particularly challenging, as increasing the number of available nuclei in the MR setup is likely to result in substantial SNR loss and degradation of image quality [38,39,40] if the utmost care is not taken. When comparing the performance of a double-or triple-tuned coil, single-tuned coils are always used as reference coils.…”

Section: Discussionmentioning

confidence: 99%

An in vivo multimodal feasibility study in a rat brain tumour model using flexible multinuclear MR and PET systems

Choi

Stegmayr

Shymanskaya

et al. 2020

Preprint

Self Cite

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Background: In addition to the structural information afforded by 1H MRI, the use of X-nuclei, such as sodium-23 (23Na) or phosphorus-31 (31P), offers important complementary information concerning physiological and biochemical parameters. By then combining this technique with PET, which provides valuable insight into a wide range of metabolic and molecular processes by using of a variety of radioactive tracers, the scope of medical imaging and diagnostics can be significantly increased. While the use of multimodal imaging is undoubtedly advantageous, identifying the optimal combination of these parameters to diagnose a specific dysfunction is very important and is advanced by the use of sophisticated imaging techniques in specific animal models. Methods: In this pilot study, rats with intracerebral 9L gliosarcomas were used to explore a combination of sequential multinuclear MRI using a sophisticated switchable coil set in a small animal 9.4 T MRI scanner and, subsequently, a small animal PET with the tumour tracer O-(2-[18F]-fluoroethyl)-L-tyrosine ([18F]FET). This made it possible for in vivo multinuclear MR-PET experiments to be conducted without compromising the performance of either multinuclear MR or PET. Results: High-quality in vivo images and spectra including high-resolution 1H imaging, 23Na-weighted imaging, detection of 31P metabolites and [18F]FET uptake were obtained, allowing the characterisation of tumour tissues in comparison to a healthy brain. It has been reported in the literature that these parameters are useful in the identification of the genetic profile of gliomas, particularly concerning the mutation of the isocitrate hydrogenase gene, which is highly relevant for treatment strategy.Conclusions: The combination of multinuclear MR and PET in, for example, brain tumour models with specific genetic mutations will enable the physiological background of signal alterations to be explored and the identification of the optimal combination of imaging parameters for the non-invasive characterisation of the molecular profile of tumours.

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Design and construction of a novel 1 H/ 19 F double-tuned coil system using PIN-diode switches at 9.4 T

Cited by 21 publications

References 27 publications

Comparison of MEMS switches and PIN diodes for switched dual tuned RF coils

Comparison of MEMS switches and PIN diodes for switched dual tuned RF coils

An in vivo multimodal feasibility study in a rat brain tumour model using flexible multinuclear MR and PET systems

An in vivo multimodal feasibility study in a rat brain tumour model using flexible multinuclear MR and PET systems

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