Fig. 4

The lobar flow (Q) for the healthy (N = 13) and idiopathic pulmonary fibrosis (IPF) subjects (N = 9). Q is defined as the difference in lobe volume normalized by the difference in lung volume between the expanded and contracted states (See Eq. 3 in the Methods Section). (a) Q values of healthy (H1-H13) and IPF subjects (D1-D9). (b) Mean values of Q for the healthy and IPF groups. The error bars denote one standard deviation and the asterisks indicate different levels of statistical significance for differences in the mean values between the two groups. (c) The root-mean-squared difference (RMSD) of Q for individual subjects (See Eq. 3 in the Methods Section). The error bars denote one standard deviation computed from 13 iterative leave-one-out validations (See Methods Section). RU denotes the right upper and right middle lobes combined. RL, LL, and LU denote the right lower, left lower, and left upper lobes, respectively