Emphysema in heavy smokers with normal chest radiography. Detection and quantification by HCRT

To determine the severity and extent of emphysema in heavy smokers by high-resolution CT (HRCT) and to correlate the findings with spirometric tests (STs) and symptomatology.

Fifty adult smokers with a mean age of 53 years with a smoking history of more than 30 pack years and normal chest radiographs underwent HRCT of the chest and ST (FEV1, FEV1/FVC, PEFR). Among these, 22 had symptoms of pulmonary disease and 28 were asymptomatic. Quantification of emphysema was done using a density mask program and the visual scoring method. The results were correlated with ST and symptomatology.

58% (29 out of 50) of the subjects had significant emphysema on HRCT. Eleven out of 15 with normal ST showed emphysema on HRCT while 2 with airflow obstruction on ST showed normal CT scores. 14% (4 out of 28) asymptomatic subjects had severe emphysema compared to 64% of symptomatic subjects. Emphysematous changes were predominantly seen in upper lung zones in 48% of the patients while in 52% it was distributed equally in both upper and lower zones. The number of pack years of smoking showed a positive correlation with CT scores. The correlation between HRCT scores and ST was statistically significant.

A significant number of asymptomatic and clinically undiagnosed smokers tend to have significant emphysema. HRCT helps in early detection of disease and thus helps implementation of preventive measures.