Measurement of pulmonary density by means of X-ray computerized tomography. Relation to pulmonary mechanics in normal subjects.

We examined the relationship between pulmonary density, measured with computerized tomography, and pulmonary mechanics (static pulmonary volume; pulmonary resistance) in 39 normal subjects (20 nonsmokers and 19 smokers). Pulmonary density decreased with increasing static elastic recoil pressure, and smokers consistently showed higher pulmonary density than nonsmokers. Pulmonary density, measured at full inspiration, correlated inversely with total lung capacity. Pulmonary density showed a ventrodorsal gradient, which was greater at low elastic recoil pressure than at high recoil pressure. The study shows that pulmonary density is related to the mechanical properties of the lung in normal subjects. Increased pulmonary density appears to be a sensitive indicator of pulmonary damage induced by smoking. Further studies of the relationship between pulmonary density and pulmonary mechanics in disease seem warranted.