Improving Signal-to-Noise Ratio of Hyperpolarized Noble Gas MR Imaging at 73.5 mT Using Multiturn Litz Wire Radiofrequency Receive Coils

Hyperpolarized noble gases ((3)He, (129)Xe) are used in Magnetic Resonance imaging as inhaled contrast agents to visualize the lung. Because the magnetization derived from hyperpolarization is independent of magnetic field strength, low magnetic fields can be used, where coil noise dominates over sample noise. It has been shown previously that signal-to-noise ratio (SNR) of hyperpolarized (129)Xe rat lung images can be improved with the use of saddle-shaped radiofrequency receive coils constructed of Litz wire in a single layer with up to 20 turns. Increased number of turns is expected to provide additional sensitivity. In this work, coils of the same geometry were built using Litz wire with either the addition of more turns (up to 48) or the addition of two layers and compared using water phantoms. It is shown that the addition of 48 turns in a single layer provided a 42% increase in SNR, when compared to the 20 turns, whereas the dual-layered approach provided no measurable benefit. (C) 2011 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 39B: 37-42, 2011