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Figure 2a. CT scans from a 6-year longitudinal study in a 27-year-old persistent current smoker (9.0 pack-years at T0; 17.0 pack-years at T1). (a) Transverse thin-section CT scan targeted to the right lung at T0 shows faint parenchymal micronodules (arrowheads) and areas of mild ground-glass attenuation in the central and peripheral parts of the upper lung zone. (b) Transverse thin-section CT scan obtained at the same level as a at T1 shows numerous ill-defined micronodules (arrowheads) diffusely distributed throughout both lungs.