Figure 1a. CT scans from a 6-year longitudinal study in a 29-year-old persistent current smoker (23.0 pack-years at T0; 29.0 pack-years at T1). (a) Transverse thin-section CT scan targeted to the right lung at T0 shows areas of hypoattenuation (arrowheads) disseminated throughout the upper lung zone, suggestive of emphysematous lesions. (b) Transverse thin-section CT scan obtained at the same level as a at T1 shows extensive emphysematous changes (arrowheads) in both lungs and more prominent septal lines. Note the long posterior junction line (arrow), suggestive of lung distention.