Transceive surface coil array for magnetic resonance imaging of the human brain at 4 T

Pinkerton, Robert G.; Barberi, Enzo A.; Menon, Ravi S.

doi:10.1002/mrm.20583

Cited by 45 publications

(38 citation statements)

References 16 publications

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“…In our case the number of elements in the array was limited by the number of receivers on our system (n=4). However, the issues associated with surface coil decoupling in the case of different array geometries can be overcome using methods we applied in this work or other recipes previously described (1,29,30). The inductive decoupling method we utilized in this work is similar in physical principle to coil overlapping (1) but can be applied for coils located at a distance and allows more accurate adjustment of the coil isolation by changing the distance between the decoupling loops.…”

Section: Resultsmentioning

confidence: 99%

4T Actively detuneable double-tuned 1H/31P head volume coil and four-channel 31P phased array for human brain spectroscopy

Avdievich

Hetherington

2007

Journal of Magnetic Resonance

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Typically 31 P in vivo magnetic resonance spectroscopic studies are limited by SNR considerations. Although phased arrays can improve the SNR; to date 31 P phased arrays for high-field systems have not been combined with 31 P volume transmit coils. Additionally, to provide anatomical reference for the 31 P studies, without removal of the coil or patient from the magnet, double-tuning ( 31 P/ 1 H) of the volume coil is required. In this work we describe a series of methods for active detuning and decoupling enabling use of phased arrays with double-tuned volume coils. To demonstrate these principles we have built and characterized an actively detuneable 31 P/ 1 H TEM volume transmit/ fourchannel 31 P phased array for 4 T magnetic resonance spectroscopic imaging (MRSI) of the human brain. The coil can be used either in volume-transmit/array-receive mode or in TEM transmit/receive mode with the array detuned. Three-fold SNR improvement was obtained at the periphery of the brain using the phased array as compared to the volume coil.

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Section: Resultsmentioning

confidence: 99%

4T Actively detuneable double-tuned 1H/31P head volume coil and four-channel 31P phased array for human brain spectroscopy

Avdievich

Hetherington

2007

Journal of Magnetic Resonance

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“…Passive decoupling schemes for transceive coils have included capacitive and inductive networks (18)(19)(20)(21)(22)(23), the intrinsic decoupling of transmission-line arrays (24)(25)(26), and partial geometric overlapping of adjacent elements (27). Capacitive decoupling becomes difficult for threedimensional (3D) arrays due to additional resonant loops caused by electrically connected elements.…”

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confidence: 99%

A conformal transceive array for 7 T neuroimaging

Gilbert

Belliveau

Curtis

et al. 2011

Magnetic Resonance in Med

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The first 16-channel transceive surface-coil array that conforms to the human head and operates at 298 MHz (7 T) is described. Individual coil elements were decoupled using circumferential shields around each element that extended orthogonally from the former. This decoupling method allowed elements to be constructed with arbitrary shape, size, and location to create a three-dimensional array. Radiofrequency shimming achieved a transmit-field uniformity of 20% over the whole brain and 14% over a single axial slice. During radiofrequency transmission, coil elements couple tightly to the head and reduce the amount of power necessary to achieve a mean 90°flip angle (660-ms and 480-ms pulse lengths were required for a 1-kW hard pulse when shimming over the whole brain and a single axial slice, respectively). During reception, the close proximity of coil elements to the head increases the signal-to-noise ratio in the periphery of the brain, most notably at the superior aspect of the head. The sensitivity profile of each element is localized beneath the respective shield. When combined with the achieved isolation between elements, this results in the capacity for low geometry factors during both transmit and receive: 1.04/1.06 (mean) and 1.25/1.54 (maximum) for 3-by-3 acceleration in the axial/sagittal plane. High cortical signal-tonoise ratio and parallel imaging performance make the conformal coil ideal for the study of high temporal and/or spatial cortical architecture and function.

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“…At the frequency of 300 MHz (Larmor frequency of proton at 7 T) or higher, it is technically challenging to design large-sized head coil [6]–[10] as the wavelength in biological tissue is significant shortened [11]–[13]. Transmit/receive (transceive) arrays have proved to be a popular choice for radio frequency (RF) coil design at ultrahigh fields [14]–[20], providing the capability of RF shimming, parallel transmission (pTx) [21]–[23], and parallel imaging [24]–[27]. …”

Section: Introductionmentioning

confidence: 99%

Multichannel Double-Row Transmission Line Array for Human MR Imaging at Ultrahigh Fields

Yan

Pedersen

Wei

et al. 2015

IEEE Trans. Biomed. Eng.

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Objective In microstrip transmission line (MTL) transmit/receive (transceive) arrays used for ultrahigh field MRI, the array length is often constrained by the required resonant frequency, limiting the image coverage. The purpose of this study is to increase the imaging coverage and also improve its parallel imaging capability by utilizing a double-row design. Methods A 16-channel double-row MTL transceive array was designed, constructed, and tested for human head imaging at 7 T. Array elements between two rows were decoupled by using the induced current elimination or magnetic wall decoupling technique. In vivo human head images were acquired, and g-factor results were calculated to evaluate the performance of this double-row array. Results Testing results showed that all coil elements were well decoupled with a better than −18 dB transmission coefficient between any two elements. The double-row array improves the imaging quality of the lower portion of the human head, and has low g-factors even at high acceleration rates. Conclusion Compared with a regular single-row MTL array, the double-row array demonstrated a larger imaging coverage along the z-direction with improved parallel imaging capability. Significance The proposed technique is particularly suitable for the design of large-sized transceive arrays with large channel counts, which ultimately benefits the imaging performance in human MRI.

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Transceive surface coil array for magnetic resonance imaging of the human brain at 4 T

Cited by 45 publications

References 16 publications

4T Actively detuneable double-tuned 1H/31P head volume coil and four-channel 31P phased array for human brain spectroscopy

4T Actively detuneable double-tuned 1H/31P head volume coil and four-channel 31P phased array for human brain spectroscopy

A conformal transceive array for 7 T neuroimaging

Multichannel Double-Row Transmission Line Array for Human MR Imaging at Ultrahigh Fields

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