A rigid, stand‐off hybrid dipole, and birdcage coil array for 7 T body imaging

Paska, Jan; Cloos, Martijn A.; Wiggins, Graham C.

doi:10.1002/mrm.27048

Cited by 24 publications

(24 citation statements)

References 32 publications

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“…RF engineering constantly searches for ways to enhance the transmission and reception of RF magnetic fields in MRI. Therefore, a combination of more than one type of coils (111), for example, BC coils and loop arrays, dipole antennas (112), microstrip coils (113), or even travel wave antennas (114), has been commonly proposed. The purpose of combination coils is to improve the performance compared to that of a single type of coil.…”

Section: Combination Coilsmentioning

confidence: 99%

A Review on the RF Coil Designs and Trends for Ultra High Field Magnetic Resonance Imaging

Hernández

Kim

2020

Investig Magn Reson Imaging

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Radiofrequency (RF) coils are a vital part of magnetic resonance imaging (MRI). It is through RF coils that a magnetic flux (|B 1 |)-field is transmitted to the imaging object to excite protons, which, in turn, emit RF signals, which are then captured by the RF coils (1). The main function of the RF coils is to transmit (Tx) and receive (Rx) signals. When the imaging object is exposed to a strong magnetic (|B 0 |)-field of the MRI scanner, its spins are magnetized, aligning them with the |B 0 |-field. Consequently, a perpendicular magnetic field is excited using an RF Tx coil, and the RF magnetic pulse deviates the spins vector from the aligned direction of |B 0 |-field. The stronger the RF

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Section: Combination Coilsmentioning

confidence: 99%

A Review on the RF Coil Designs and Trends for Ultra High Field Magnetic Resonance Imaging

Hernández

Kim

2020

Investig Magn Reson Imaging

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“…With such local coil arrays it is possible to use elements that are for both transmit and receive, or to split transmit and receive by using transmit‐only and receive‐only elements . Also, a combination of TxRx and Rx‐only elements is possible . Receive‐only elements are usually designed as loops because they can be overlapped for decoupling.…”

Section: Introductionmentioning

confidence: 99%

“…It is also possible to influence the coupling behavior of this element type for array construction . In 7T body imaging, the aforementioned elements and coils have been applied for cardiac, abdominal, and pelvic imaging …”

Section: Introductionmentioning

confidence: 99%

“…24 Also, a combination of TxRx and Rx-only elements is possible. [25][26][27][28] Receive-only elements are usually designed as loops because they can be overlapped for decoupling. Normally, loops surround the subject closely and seamlessly for high SNR.…”

Section: Introductionmentioning

confidence: 99%

“…It is also possible to influence the coupling behavior of this element type for array construction. 35 In 7T body imaging, the aforementioned elements and coils have been applied for cardiac, 20,22,23,26,27 abdominal, 20,27,28 and pelvic imaging. 20,27 Receive coils for body imaging should generally provide sufficient coverage, especially in z-direction along the main magnetic field, improved acceleration capabilities (lower g-factors), and most importantly high SNR.…”

Section: Introductionmentioning

confidence: 99%

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Development and evaluation of a 16‐channel receive‐only RF coil to improve 7T ultra‐high field body MRI with focus on the spine

Rietsch

Brunheim

Orzada

et al. 2019

Magnetic Resonance in Med

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Purpose A 16‐channel receive (16Rx) radiofrequency (RF) array for 7T ultra‐high field body MR imaging is presented. The coil is evaluated in conjunction with a 16‐channel transmit/receive (16TxRx) coil and additionally with a 32‐channel transmit/receive (32TxRx) remote body coil for RF transmit and serving as receive references. Methods The 16Rx array consists of 16 octagonal overlapping loops connected to custom‐built detuning boards with preamplifiers. Performance metrics like noise correlation, g‐factors, and signal‐to‐noise ratio gain were compared between 4 different RF coil configurations. In vivo body imaging was performed in volunteers using radiofrequency shimming, time interleaved acquisition of modes (TIAMO), and 2D spatially selective excitation using parallel transmit (pTx) in the spine. Results Lower g‐factors were obtained when using the 16Rx coil in addition to the 16TxRx array coil configuration versus the 16TxRx array alone. Distinct signal‐to‐noise ratio gain using the 16Rx coil could be demonstrated in the spine region both for a comparison with the 16TxRx coil (>50% gain) in vivo and the 32TxRx coil (>240% gain) in a phantom. The 16Rx coil was successfully applied to improve anatomical imaging in the abdomen and 2D spatially selective excitation in the spine of volunteers. Conclusion The novel 16‐channel Rx‐array as an add‐on to multichannel TxRx RF coil configurations provides increased signal‐to‐noise ratio, lower g‐factors, and thus improves 7T ultra‐high field body MR imaging.

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An 8‐element Tx/Rx array utilizing MEMS detuning combined with 6 Rx loops for ¹⁹F and ¹H lung imaging at 1.5T

Maunder

Rao

Robb

et al. 2020

Magnetic Resonance in Med

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To firstly improve the attainable image signal-to-noise ratio (SNR) of 19 F and 1 H C3F8 lung imaging at 1.5T using an 8-element transmit/receive (Tx/Rx) flexible vest array combined with a 6-element Rx-only array, and secondly, to evaluate MEMS for switching the array elements between the two resonant frequencies.Methods:The Tx efficiency and homogeneity of the 8-element array was measured and simulated for 1 H imaging in a cylindrical phantom and then evaluated for in-vivo 19 F/ 1 H imaging. The added improvement provided by the 6-element Rx-only array was quantified through simulation and measurement and was compared to the ultimate SNR (uSNR). It was verified through the measurement of isolation, that MEMS switches provided broadband isolation of Tx/Rx circuitry such that the 19 F tuned Tx/Rx array could be effectively used for both 19 F and 1 H nuclei.Results: For 1 H imaging, the measured Tx efficiency/homogeneity (mean±percent standard deviation; 6.79 /√ ± 26%) was comparable to that simulated (7.57 /√ ± 20%).The 6 additional Rx-only loops increased the mean Rx sensitivity when compared to the 8element array, by a factor of 1.41x and 1.45x in simulation and measurement, respectively. In regions central to the thorax the simulated SNR of the 14-element array achieves >=70% of the uSNR when including noise from the matching circuits and preamplifiers. A measured MEMS switching speed of 12 µs and added minimum 22 dB of isolation between Tx and Rx was sufficient for Tx/Rx switching in this application. Conclusion:The described single tuned array driven at 19 F and 1 H, utilizing MEMS technology, provides excellent results for 19 F and 1 H dual-nuclear lung ventilation imaging.

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A rigid, stand‐off hybrid dipole, and birdcage coil array for 7 T body imaging

Cited by 24 publications

References 32 publications

A Review on the RF Coil Designs and Trends for Ultra High Field Magnetic Resonance Imaging

A Review on the RF Coil Designs and Trends for Ultra High Field Magnetic Resonance Imaging

Development and evaluation of a 16‐channel receive‐only RF coil to improve 7T ultra‐high field body MRI with focus on the spine

An 8‐element Tx/Rx array utilizing MEMS detuning combined with 6 Rx loops for ¹⁹F and ¹H lung imaging at 1.5T

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A rigid, stand‐off hybrid dipole, and birdcage coil array for 7 T body imaging

Cited by 24 publications

References 32 publications

A Review on the RF Coil Designs and Trends for Ultra High Field Magnetic Resonance Imaging

A Review on the RF Coil Designs and Trends for Ultra High Field Magnetic Resonance Imaging

Development and evaluation of a 16‐channel receive‐only RF coil to improve 7T ultra‐high field body MRI with focus on the spine

An 8‐element Tx/Rx array utilizing MEMS detuning combined with 6 Rx loops for 19F and 1H lung imaging at 1.5T

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Product

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An 8‐element Tx/Rx array utilizing MEMS detuning combined with 6 Rx loops for ¹⁹F and ¹H lung imaging at 1.5T