Abstract
BackgroundTo support translational lung MRI research with hyperpolarized 129Xe gas, comprehensive evaluation of derived quantitative lung function measures against established measures from 3He MRI is required. Few comparative studies have been performed to date, only at 3T, and multisession repeatability of 129Xe functional metrics have not been reported.Purpose/HypothesisTo compare hyperpolarized 129Xe and 3He MRI‐derived quantitative metrics of lung ventilation and microstructure, and their repeatability, at 1.5T.Study TypeRetrospective.PopulationFourteen healthy nonsmokers (HN), five exsmokers (ES), five patients with chronic obstructive pulmonary disease (COPD), and 16 patients with nonsmall‐cell lung cancer (NSCLC).Field Strength/Sequence1.5T. NSCLC, COPD patients and selected HN subjects underwent 3D balanced steady‐state free‐precession lung ventilation MRI using both 3He and 129Xe. Selected HN, all ES, and COPD patients underwent 2D multislice spoiled gradient‐echo diffusion‐weighted lung MRI using both hyperpolarized gas nuclei.AssessmentVentilated volume percentages (VV%) and mean apparent diffusion coefficients (ADC) were derived from imaging. COPD patients performed the whole MR protocol in four separate scan sessions to assess repeatability. Same‐day pulmonary function tests were performed.Statistical TestsIntermetric correlations: Spearman's coefficient. Intergroup/internuclei differences: analysis of variance / Wilcoxon's signed rank. Repeatability: coefficient of variation (CV), intraclass correlation (ICC) coefficient.ResultsA significant positive correlation between 3He and 129Xe VV% was observed (r = 0.860, P < 0.001). VV% was larger for 3He than 129Xe (P = 0.001); average bias, 8.79%. A strong correlation between mean 3He and 129Xe ADC was obtained (r = 0.922, P < 0.001). MR parameters exhibited good correlations with pulmonary function tests. In COPD patients, mean CV of 3He and 129Xe VV% was 4.08% and 13.01%, respectively, with ICC coefficients of 0.541 (P = 0.061) and 0.458 (P = 0.095). Mean 3He and 129Xe ADC values were highly repeatable (mean CV: 2.98%, 2.77%, respectively; ICC: 0.995, P < 0.001; 0.936, P < 0.001).Data Conclusion 129Xe lung MRI provides near‐equivalent information to 3He for quantitative lung ventilation and microstructural MRI at 1.5T. Level of Evidence: 3 Technical Efficacy Stage 2J. Magn. Reson. Imaging 2018;48:632–642.
Highlights
To support translational lung MRI research with hyperpolarized 129Xe gas, comprehensive evaluation of derived quantitative lung function measures against established measures from 3He MRI is required
This work indicates that 129Xe lung MRI can provide equivalent regional information on lung ventilation and microstructure to 3He MRI at to-date the most-reported field strength for lung MRI, 1.5T
We demonstrated a clear agreement between 129Xe ventilation and diffusion MRI measurements and 3He equivalent measurements; these findings substantiate previous work from the Robarts group that was performed at 3T with lower spatial resolution imaging.[3,15,16]
Summary
To support translational lung MRI research with hyperpolarized 129Xe gas, comprehensive evaluation of derived quantitative lung function measures against established measures from 3He MRI is required. Few comparative studies have been performed to date, only at 3T, and multisession repeatability of 129Xe functional metrics have not been reported. Purpose/Hypothesis: To compare hyperpolarized 129Xe and 3He MRI-derived quantitative metrics of lung ventilation and microstructure, and their repeatability, at 1.5T. Assessment: Ventilated volume percentages (VV%) and mean apparent diffusion coefficients (ADC) were derived from imaging. MR parameters exhibited good correlations with pulmonary function tests. In COPD patients, mean CV of 3He and 129Xe VV% was 4.08% and 13.01%, respectively, with ICC coefficients of 0.541 (P 5 0.061) and 0.458 (P 5 0.095).
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