Definition and terms relating to pulmonary nodules (see also figures 5 and 6)
| Pulmonary nodule | Focal, rounded opacity ≤3 cm diameter, mostly surrounded by aerated lung, including contact with pleura, but without potentially related abnormalities in the thorax |
| Sub-solid nodule (SSN) | A part-solid or pGGN |
| Part-solid nodule (PSN) (b) | A focal opacity that has both solid and ground-glass component ≤3 cm diameter |
| pGGN (c) (synonymous with non-solid nodule) | A focal ground-glass opacity ≤3 cm diameter that does not obscure vascular pattern |
| Solid component | The part of a nodule that obscures the underlying bronchovascular structure |
| Ground glass | Opacification that is greater than that of the background but through which the underlying vascular structure is visible |
pGGN, pure ground-glass nodule.