Figure 1b. T1 N0 bronchioloalveolar carcinoma (BAC) in a 53-year-old man. (a) Initial transaxial thin-section (1-mm collimation, 170 mA) CT scan (lung window) obtained at the level of the bronchus intermedius shows a small nodular area of ground-glass attenuation in the right upper lobe (arrow). (b) Follow-up CT scan (5-mm collimation, 50 mA) obtained 48 months later shows increased nodule size (arrow). The lobectomy specimen showed BAC without nodal metastasis.