Figure 3.

Measurements of MLD and maximum cardiac CSA.

Notes: A non-COPD smoker (as shown in Figure 1) showed similar time curves (A), suggesting that cardiac CSA decreased with inspiration and increased with expiration (CCC of all frames =0.987). The cardiac CSA measurements were performed on axial CT images Video S1. In a severe COPD patient (as shown in Figure 2), measurements of MLD and maximum cardiac CSA demonstrated almost opposite shapes (B), suggesting that the heart size increased during inspiration and decreased during expiration. The CCC of the entire cycle was −0.392, and that of the expiratory frames (frame no 6–13 in this case) was −0.723. CT images are available from Video S2.

Abbreviations: CCC, cross-correlation coefficient; CSA, cross-sectional area; CT, computed tomography; HU, Hounsfield unit; MLD, mean lung density.