Transmit-only/receive-only radiofrequency coil configuration for hyperpolarized 129Xe MRI of rat lungs

We report a novel radiofrequency (RF) transmit-only/receive-only (TO/RO) coil configuration providing excellent transmit B₁₊ field uniformity as well as high sensitivity for hyperpolarized ¹²⁹Xe MR lung imaging of rats at 3T (35.34 MHz). The TO/RO coil configuration consisted of two separate components: (i) a high-pass birdcage transmit coil which produces a homogeneous B₁₊ magnetic field, (ii) a saddle-shaped single-turn receive-only surface coil that couples closely to the rat lung. On transmit, the receive-only coil is decoupled from the transmit coil using a detuning circuit. On receive, the bird-cage coil is deactivated through the use of PIN diodes. The sensitivity and uniformity of the saddle-shaped receive coil were optimized solving the Biot-Savart equation using 3D finite element modeling. The electrical performance of the new TO/RO configuration in transmit/receive (T/R) mode was compared with a commercial T/R birdcage coil of similar diameter, which was considering to be the gold standard for conventional T/R mode imaging. Experimental results in phantoms confirm that our novel TO/RO coil configuration provides a factor of three increase in SNR without compromising B₁ transmit uniformity compared with the commercial T/R birdcage coil configuration. The novel TO/RO coil was successfully tested for in vivo rat lung imaging. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 45B: 115–124, 2015