A flexible 32‐channel receive array combined with a homogeneous transmit coil for human lung imaging with hyperpolarized 3 He at 1.5 T

Parallel imaging presents a promising approach for MRI of hyperpolarized nuclei, as the penalty in signal‐to‐noise ratio typically encountered with 1 H MRI due to a reduction in acquisition time can be offset by an increase in flip angle. The signal‐to‐noise ratio of hyperpolarized MRI generally exhibits a strong dependence on flip angle, which makes a homogeneous B 1 + transmit field desirable. This paper presents a flexible 32‐channel receive array for 3 He human lung imaging at 1.5T designed for insertion into an asymmetric birdcage transmit coil. While the 32‐channel array allows parallel imaging at high acceleration factors, the birdcage transmit coil provides a homogeneous B 1 + field. Decoupling between array elements is achieved by using a concentric shielding approach together with preamplifier decoupling. Coupling between transmit coil and array elements is low by virtue of a low geometric coupling coefficient, which is reduced further by the concentric shields in the array. The combination of the 32‐channel array and birdcage transmit coil provides 3 He ventilation images of excellent quality with similar signal‐to‐noise ratio at acceleration factors R = 2 and R = 4, while maintaining a homogeneous B 1 + . Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.