Regional lung density and blood volume in nonsmoking and smoking subjects measured by PET

Regional lung density (DL) and regional fractional pulmonary blood volume (VB) were measured quantitatively during tidal breathing in 30 healthy supine subjects (15 smokers and 15 nonsmokers) in a 1.7-cm-thick midthoracic cross section using positron emission tomography (PET) and 11CO (inhaled)-labeled erythrocytes. Regional alveolar volume (VA), extravascular lung density (DEV), and relative alveolar size (Valv = VA/DEV) were calculated. For the nonsmokers, mean values (+/- SD between subjects) for the right lung were as follows: DL, 0.28 +/- 0.03 g/cm3; DEV, 0.10 +/- 0.02 g/cm3; and Valv, 7.1 +/- 1.9 ml/g lung tissue. In the smoking subjects DEV (right plus left lung) was 16% higher. No significant difference in VB between smokers and nonsmokers was found. The differences in DEV and VB between right and left lung were not significant. Mean values (+/- SD) of the dorsal-to-ventral ratios calculated for the right lung in the nonsmokers were as follows: DL, 1.34 +/- 0.16; VA, 0.90 +/- 0.05; VB, 1.52 +/- 0.26; DEV, 1.10 +/- 0.17; and Valv, 0.85 +/- 0.19. Almost identical ratios were found in the smokers. The influence of overall thoracic expansion was investigated in one subject restudied during voluntary hyperinflation and during positive end-expiratory pressure.