A conformal transceive array for 7 T neuroimaging

作者：Gilbert Kyle M^*; Belliveau Jean Guy; Curtis Andrew T; Gati Joseph S; Klassen L Martyn; Menon Ravi S

来源：Magnetic Resonance in Medicine, 2012, 67(5): 1487-1496.

DOI：10.1002/mrm.23124

• transmit array
• transceiver
• radiofrequency coil
• decoupling
• parallel imaging
• signal-to-noise ratio

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 degrees flip angle (660-mu s and 480-mu s 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-to-noise ratio and parallel imaging performance make the conformal coil ideal for the study of high temporal and/or spatial cortical architecture and function. Magn Reson Med, 2012.

• 出版日期2012-5