Bland-Altman plots of ventilated volume (%VV; A) and heterogeneity score (Hscore; B)generated from images acquired with hyperpolarized 129Xe at all acquisition volumes. Black dots indicate bias, gray dots are the 95% confidence intervals, and the black dashed line is 0. RV, residual volume; RV + 1L, residual volume plus 1 liter of gas mixture; FRC, functional residual capacity; FRC + 1L, functional residual capacity volume plus 1 liter of gas mixture; TLC, total lung capacity.