FACTORS INFLUENCING LUNG DENSITY IN EXPERIMENTAL-MODELS - RESULTS OF STUDIES USING CT DENSITOMETRY

Lung density measurements using computed tomography have been made in mice, rats, and pure-bred beagles and mongrel dogs. Density was found to be dependent on a number of factors including the location of the a rea scanned, and the age and species of the animal. Lung density was f ound to decrease by approximately 40% from initial values in a group o f rats scanned at intervals between 30 and 800 days old. Age-related d ensity changes were not seen for the lungs of mice or dogs; however me asurements were not made over a prolonged period. A gradient of increa sing density from the base to apex of the lung was seen for 30 and 175 -day-old rats (scanned in the prone position) while an apex to base de nsity gradient was seen for both types of dog studied (scanned in the supine position). In none of the species studied was there a systemati c difference in density of the right and left lungs. Differences in av erage lung density between the mice, rats and dogs reported here are c onsistent with the relationship between lung morphology, metabolic rat e and body size which obtains for a range of mammalian species.