Ground-glass nodule on thin-section CT: Differentiation among adenocarcinoma in situ, minimally invasive adenocarcinoma and lepidic predominant invasive adenocarcinoma

To investigate different computed tomography (CT) features among adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and lepidic predominant invasive adenocarcinoma (LPA) that appeared as ground-glass nodules (GGN). We also analyzed different CT findings between Group A (AIS and MIA) and Group B (LPA). We evaluated 19 AIS, 4 MIA, and 9 LPA images that were histologically confirmed and manifested as GGN on thin-section CT scans. CT scans were assessed for lesion characteristics: size, shape, solid portion, internal air density, marginal irregularity and pleural tag. CT findings of Group A and Group B were analyzed using the Kruskal-Wallis test or Fisher's exact test. A significant statistical difference was seen between AIS and LPA for lesion characteristics (p < 0.05). No significant difference was observed between AIS and MIA. Round or polygonal shape with smooth margin was significantly associated with Group A, and complex shape with marginal irregularity was associated with Group B. Group A (AIS and MIA) could be distinguished from Group B (LPA) by smaller lesion size, round or polygonal shape, smaller solid portion and smooth margin