Transmit‐receive coil‐arrays at 17.6T, configurations for 1H, 23Na, and 31P MRI

Array coil imaging is a popular technique in whole-body MRI systems but has seldom been implemented in vertical bore high-field magnets. In this work, three transmit-receive phased arrays for 1H, 23Na, and 31P were built to examine the feasibility of using these arrays at the magnetic field strength of 17.6 Tesla. The coils were designed for in vivo applications on mice and rats with an inner diameter of 38 mm. Each array consisted of two surface coils. The decoupling of adjacent coils was achieved by a variable decoupling capacitor on the common conductor of the two surface-coils. The coils can be driven simultaneously to provide an area of relatively high transmit homogeneity using a relative phase shift between the coils. The area with best homogeneity changes, depending on this phase shift. Images were simultaneously acquired with two receivers and showed essentially no coupling between the two channels. The arrays provide an SNR-gain compared to a single-channel birdcage-volume resonator of up to 34% near the surface. The arrays are most suitable for objects near the coils with a penetration depth of up to 20 mm (e.g., the spinal cord or the brain of a rat) © 2006 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 29B: 20–27, 2006