Surface coil with variable geometry: a new tool for MR imaging of the spine.

Requardt, Hermann; Offermann, J; Kess, Helmut; Krause, Norbert; Weber, Hans

doi:10.1148/radiology.165.2.3659389

Cited by 9 publications

(4 citation statements)

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“…Next, switched loop elements arranged in arrays, which received the MR signal individually by detuning the other elements in the array, were developed to adjust the sensitivity pattern of such an array, in order to optimize the single receiver for use in arrays . A major step in the development of arrays was the adaptation of mobile phased‐array radar technology, in the reception of NMR signals.…”

Section: The Evolution Of Mri Rf Coilsmentioning

confidence: 99%

RF coils: A practical guide for nonphysicists

Gruber

Froeling

Leiner

et al. 2018

Magnetic Resonance Imaging

161

136

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Radiofrequency (RF) coils are an essential MRI hardware component. They directly impact the spatial and temporal resolution, sensitivity, and uniformity in MRI. Advances in RF hardware have resulted in a variety of designs optimized for specific clinical applications. RF coils are the “antennas” of the MRI system and have two functions: first, to excite the magnetization by broadcasting the RF power (Tx‐Coil) and second to receive the signal from the excited spins (Rx‐Coil). Transmit RF Coils emit magnetic field pulses ( normalB1+) to rotate the net magnetization away from its alignment with the main magnetic field (B0), resulting in a transverse precessing magnetization. Due to the precession around the static main magnetic field, the magnetic flux in the receive RF Coil ( normalB1−) changes, which generates a current I. This signal is “picked‐up” by an antenna and preamplified, usually mixed down to a lower frequency, digitized, and processed by a computer to finally reconstruct an image or a spectrum. Transmit and receive functionality can be combined in one RF Coil (Tx/Rx Coils). This review looks at the fundamental principles of an MRI RF coil from the perspective of clinicians and MR technicians and summarizes the current advances and developments in technology. Level of Evidence: 1 Technical Efficacy: Stage 6 J. Magn. Reson. Imaging 2018;48:590–604.

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Section: The Evolution Of Mri Rf Coilsmentioning

confidence: 99%

RF coils: A practical guide for nonphysicists

Gruber

Froeling

Leiner

et al. 2018

Magnetic Resonance Imaging

161

136

View full text Add to dashboard Cite

show abstract

“…High-resistivity Teflon-coated carbon wires were used for the dc bias and ground connections, eliminating the need for RF traps. Alternatively, PIN diodes have been used by several authors for detuning coils without significant degradation of SNR (8,9,18,19). Of course, when PIN diodes are used, the detuning circuit should be designed so that the diodes are open circuited when the coil is resonated to avoid significant degradation of the Q factor.…”

Section: Methodsmentioning

confidence: 99%

“…However, this is a very expensive solution due to the high cost of the additional receiver channels. Alternatively, several groups have proposed multiple-coil systems with selectable sensitive regions for several applications, including switched bilateral imaging of the temporomandibular joints and knees (2-5), spine imaging (4,(6)(7)(8), and abdominal imaging ( 9 ) . We have developed a new method for remotely selecting the sensitive region of a surface coil by using mutually coupled coil arrays.…”

Section: Introductionmentioning

confidence: 99%

Arrays of mutually coupled receiver coils: Theory and application

Wright

Magin

Kelton

1991

Magnetic Resonance in Med

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Specialized receiver coils having a small sensitive region can provide an improvement in SNR for MR imaging and spectroscopy, at the expense of limiting the usable field of view. This work presents a technique for designing coil arrays that allows the size and location of the sensitive region to be selected remotely. Only one element of the coil array is directly connected to the receiver, allowing flexibility in system design and implementation. A method is presented for the analysis and design of mutually coupled coil arrays of any number of elements of arbitrary shape. The analysis includes mutual coupling effects between primary coils, to allow multiple primary coils to be used simultaneously. A controller system allows remote selection of the sensitive region and automatically matches the impedance of the array to the preamplifier. Results obtained using a mutually coupled coil array designed for spine imaging are shown.

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“…Several workers have attempted to solve this problem by constructing coils which either can be repositioned ( 1 0 ) or have sets of elements which can be switched into place to change the field of view (11)(12)(13). Repositioning devices can be very effective and easy to use because there is no need to reposition the patient: the coil simply moves in a space created between the patient and the table.…”

Section: Introductionmentioning

confidence: 99%

A continuously variable field of view surface coil

Duensing

Fitzsimmons

Sanford

et al. 1990

Magnetic Resonance in Med

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A new type of surface coil is described which allows the user to continuously vary the size of the field of view. This utilizes a modified radiofrequency trombone for size adjustment that results in a stable frequency over a wide range of dimensions. Results show that the coil may be increased in area by as much as 60% while maintaining frequency stability to ca. 1 MHz at 63.5 MHz. Images of the human spine are presented to demonstrate the clinical utility of the new design.

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Surface coil with variable geometry: a new tool for MR imaging of the spine.

Cited by 9 publications

References 0 publications

RF coils: A practical guide for nonphysicists

RF coils: A practical guide for nonphysicists

Arrays of mutually coupled receiver coils: Theory and application

A continuously variable field of view surface coil

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