A variability study of regional alveolar oxygen tension measurement in humans using hyperpolarized ³He MRI

Purpose A systematic study of the short-term and long-term variability of regional alveolar partial pressure of oxygen tension (p_AO ₂) measurements using ³He magnetic resonance imaging was presented. Additionally, the repeatability of the average evaluated p _AO₂ was compared with that of the standard pulmonary function tests. Methods Pulmonary function test and p_AO₂ imaging were performed on 4 nonsmokers (1 M, 3 F, 56 ± 1.7 years) and 4 smokers (3 M, 1 F, 52 ± 7.5 years) during three visits over the course of 2 weeks. Two measurements were performed per visit. Variability of p _AO₂ was assessed using a mixed-effect model, with an intraclass correlation coefficient calculated for each group. The coefficient of variation of p_AO₂ over the 3-day period was also compared with the coefficient of variation of pulmonary function test results. Results Short-term regional variability based on intraclass correlation coefficient was 0.71 for nonsmokers, and 0.63 for smokers, with long-term variability significantly lower at 0.59 and 0.47, respectively. While the coefficient of variation of the average p_AO₂ was similar to the repeatability of the diffusing capacity of CO, it was significantly higher than that of Forced Vital Capacity (P = 0.02). Conclusion Short-term and long-term p_AO₂ variability differences were used as an indication of true physiological changes in order to measure technical reproducibility. Smokers show higher physiologic variability and less technical reproducibility. The suggested p_AO₂-imaging technique showed a reasonable regional repeatability in nonsmokers as well as the ability to detect differences between the two groups with similar reproducibility and superior discriminatory ability when compared with pulmonary function tests. Magn Reson Med 70:1557-1566, 2013. © 2013 Wiley Periodicals, Inc.