Correct!
1. The thoracic CT shows multiple nodules and cavities

Multiple variably sized nodules and cavities are present. The dominant lesion, as seen on the chest radiograph, is present in the left lower lobe, but another cavity is present in the medial aspect of the superior segment of the left lower lobe, and small nodules are also seen in the upper and lower lobes bilaterally. The term “perilymphatic” is usually applied to small nodules, typically ≤1 cm, that are primarily seen along bronchovascular structures, interlobular septae, and fissural surfaces. Perilymphatic nodules are commonly encountered in diseases affecting the lymphatic system, such as sarcoidosis and caricinomatosis. While some of the nodules on this thoracic CT are seen along bronchovascular bundles, the nodules are not related to the fissures, making a perilymphatic distribution unlikely. Similarly, a random, or “miliary,” pattern is typically said to be present when small nodules are seen diffusely distributed throughout the lung, relatively equally in relation to fissural surfaces, along bronchovascular structures, and in the centrilobular regions. This pattern is typical of processes spreading hematogenously to the lung, but is not present in this case.  Multifocal ground-glass opacity is not present in this case. A few foci of ground-glass attenuation are seen around the dominant left lower lobe cavity and in a peribronchial location, but these findings are minor in comparison with other abnormalities on the scan. High attenuation mucous impaction, typical of allergic bronchopulmonary aspergillosis, cannot be diagnosed when presented with only lung window images; soft tissue windows are needed for such an assessment. The slightly wider window widths and levels used for the coronal image set (Figure 2C) do not show high attenuation bronchial impaction. Finally, while some peribronchial opacity is present, clear evidence of bronchiectasis and mucous impaction is not seen.

Regarding the assessment of lung cavities at chest radiography, which of the following is correct?

1. The wall thickness of a lung cavity should be assessed at its thickest portion
2. The presence of an air-fluid level within a lung cavity is diagnostic of lung abscess
3. Malignant causes of lung cavities usually produce cavities with a smooth inner lining
4. When the thinnest portion of a lung cavity is ˂2 mm, the cavity is unequivocally benign

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