Figure 1a. Pseudo-ground-glass opacity at CT in a 53-year-old man. (a) Axial low-dose CT image (5-mm-thick section) shows a nodular ground-glass opacity in the upper lobe of the left lung. No solid component is visible in the 10-mm poorly marginated lesion. (b) Thin-section CT image obtained at the level of the aortic arch depicts a well-defined oval solid nodule instead of the nodular ground-glass opacity shown in a. (c) CT image obtained with a mediastinal window setting shows a densely calcified granuloma.