Feasibility of human lung ventilation imaging using highly polarized naturally abundant xenon and optimized three-dimensional steady-state free precession.
OBJECTIVE
To demonstrate the potential for high quality MRI of pulmonary ventilation using naturally abundant xenon (NAXe) gas.


METHODS
MRI was performed at 1.5 Tesla (T) and 3 T on one healthy smoker and two healthy never-smokers. 129Xe gas was polarized 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 3He.


RESULTS
All NAXe lung images were of high quality, with mean SNRs of 25-40 (voxel 4.2 × 4.2 × 8/10 mm3) and ∼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 3He.


CONCLUSIONS
Optimization of MR pulse sequences and advances in polarization technology have facilitated high quality pulmonary ventilation imaging with inexpensive NAXe gas.
Academic Unit of Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, United Kingdom.
Neil J
http://orcid.org/0000-0001-8358-394X
NJ
Stewart
Academic Unit of Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, United Kingdom.
Graham
G
Norquay
Academic Unit of Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, United Kingdom.
Paul D
PD
Griffiths
Academic Unit of Radiology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, United Kingdom.
Jim M
JM
Wild
D000328:Adult; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008168:Lung / Q000473:pathology* / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011659:Pulmonary Gas Exchange; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012907:Smoking / Q000503:physiopathology*; D014979:Xenon Isotopes / Q000493:pharmacokinetics*
D019275:Radiopharmaceuticals; D014979:Xenon Isotopes
3D steady-state free precession; hyperpolarized gas; lung ventilation imaging; naturally abundant xenon-129