PCA of strain metrics from initial CT chest show early BOS has qCT values intermediate between NIH-BOS and controls or transient impairment. PC1 is the first principal component. PC2 is the second principal component. Each arrow represents a strain metric, with the arrow direction representing its contribution to a PC and the arrow length representing the magnitude of its contribution to the statistical variance of the data set. Each ellipse is the normal probability for the group. The units of each axis are a composite of linear combinations of the original strain metrics.