Feasibility of human lung ventilation imaging using highly polarized naturally abundant xenon and optimized three-dimensional steady-state free precession

PurposeTo demonstrate the potential for high quality MRI of pulmonary ventilation using naturally abundant xenon (NAXe) gas. MethodsMRI was performed at 1.5 Tesla (T) and 3 T on one healthy smoker and two healthy never-smokers. Xe-129 gas was polarized to approximate to 25% using an in-house spin-exchange optical pumping polarizer fitted with a laser diode array with integrated volume holographic grating and optical train system. Volunteers inhaled 1 L of NAXe for an 8 to 15 s breathhold while MR images were acquired with full-lung coverage using a three-dimensional steady-state free precession sequence, optimized for maximum signal-to-noise ratio (SNR) at a given spatial resolution. For the purpose of image quality comparison, the MR acquisition was repeated at 1.5 T with 400 mL enriched xenon and 200 mL He-3. ResultsAll NAXe lung images were of high quality, with mean SNRs of 25-40 (voxel 4.2 x 4.2 x 8/10 mm(3)) and approximate to 30% improvement at 3 T versus 1.5 T. The high SNR permitted identification of minor ventilation defects in the healthy smoker's lungs. NAXe images were of comparable SNR to those obtained with enriched xenon and He-3. ConclusionOptimization of MR pulse sequences and advances in polarization technology have facilitated high quality pulmonary ventilation imaging with inexpensive NAXe gas. Magn Reson Med 74:346-352, 2015. (c) 2015 Wiley Periodicals, Inc.