Dissolved hyperpolarized xenon-129 MRI in human kidneys

Purpose To assess the feasibility of using dissolved hyperpolarized xenon-129 (Xe-129) MRI to study renal physiology in humans at 3 T. Methods Using a flexible transceiver RF coil, dynamic and spatially resolved Xe-129 spectroscopy was performed in the abdomen after inhalation of hyperpolarized Xe-129 gas with 3 healthy male volunteers. A transmit-only receive-only RF coil array was purpose-built to focus RF excitation and enhance sensitivity for dynamic imaging of Xe-129 uptake in the kidneys using spoiled gradient echo and balanced steady-state sequences. Results Using spatially resolved spectroscopy, different magnitudes of signal from Xe-129 dissolved in red blood cells and tissue/plasma could be identified in the kidneys and the aorta. The spectra from both kidneys showed peaks with similar amplitudes and chemical shift values. Imaging with the purpose-built coil array was shown to provide more than a 3-fold higher SNR in the kidneys when compared with surrounding tissues, while further physiological information from the dissolved Xe-129 in the lungs and in transit to the kidneys was provided with the transceiver coil. The signal of dissolved hyperpolarized Xe-129 could be imaged with both tested sequences for about 40 seconds after inhalation. Conclusion The uptake of Xe-129 dissolved in the human kidneys was measured with spectroscopic and imaging experiments, demonstrating the potential of hyperpolarized Xe-129 MR as a novel, noninvasive technique to image human kidney tissue perfusion.