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

As the static magnetic field strength used in human magnetic resonance imaging increases, the wavelength of the corresponding radiofrequency field becomes comparable to the dimensions of the coil and volume of interest. The dielectric resonance effects that arise in this full wavelength regime may be partially compensated for through the use of surface coils. A novel high‐field (4 T) transceive surface coil array is presented that allows arbitrary surface coil placement and size while maintaining the ability to independently transmit and/or receive through conventional 50‐Ω power amplifiers and preamplifiers, respectively. A ninefold signal‐to‐noise ratio (SNR) increase is shown in close proximity to the transceive array and there is an overall 38% increase throughout the entire brain volume in comparison to the standard hybrid birdcage coil. Furthermore, the ability to independently transmit and receive through each surface coil within this array enables transmit and/or receive‐only fast parallel imaging techniques to be employed while maintaining the increased SNR sensitivity inherent to surface coil designs. Magn Reson Med 54:499–503, 2005. © 2005 Wiley‐Liss, Inc.