Resolving small pulmonary nodules: CT features

Our aim was to analyse the CT morphology of resolving nodules over time in order seek morphologic features helpful in initial nodule classification. The imaging characteristics of 133 consecutive resolving pulmonary nodules detected in 56 subjects in a screening trial for early lung cancer with low-dose CT were retrospectively reviewed by two readers in consensus. Nodule size ranged from 2 to 28 mm, with a mean diameter of 5.9 mm. The maximum diameter of resolving nodules was < or =5 mm in 71/133 (53%), 6-10 mm in 52/133 (39%), and >10 mm in 10/133 (8%). Their location was mainly peripheral, with a mean distance to the costal pleura of 10 mm. There was no lobe predominance of nodules. In 85% (113/133) of cases the nodules were solid, 77% (103/133) were well-defined, and 73% (97/133) were non-lobulated. Eighty percent (107/133) resolved completely within 14-1,671 (mean 492) days, 20% (26/133) resolved incompletely with residual abnormalities within 51-1,777 (mean 613) days. Resolving pulmonary nodules were mostly < or =10 mm, peripherally located, solid, well-defined, and non-lobulated. Most resolve completely within a variable interval ranging from several days to years.