Purpose: To evaluate thin-section computed tomography (CT) in depicting longitudinal changes in the lung parenchyma.
Materials and methods: One hundred eleven volunteers underwent sequential examination with thin-section CT and pulmonary function tests over a mean period of 5.5 years. According to their smoking habits between initial evaluation (T0) and follow-up (T1), the subjects were classified as persistent current smokers (n = 57), persistent nonsmokers (n = 31), persistent ex-smokers (n = 13), or quitters (n = 10).
Results: Significant differences in CT findings between T0 and T1 were seen in only the group of persistent current smokers, who showed a higher frequency of emphysema (40% vs 26%; P =.005) and ground-glass attenuation (42% vs 28%; P =.02). Individual analysis of follow-up CT scans in the 19 persistent current smokers with micronodules at T0 demonstrated (a) no changes in seven cases, (b) a higher profusion of micronodules in seven cases, and (c) replacement of micronodules with emphysema in five cases. Subjects with emphysema and/or areas of ground-glass attenuation at T0 had a significantly more rapid decline in lung function than did those with a normal CT scan.
Conclusion: Emphysema and/or ground-glass attenuation are linked with impairment of ventilatory lung function over time in persistent current smokers.