To investigate the value of contrast-enhanced CT scans in differential diagnosis of atypical adenomatous hyperplasia (AAH), adenocarcinoma in situ (AIS), minimal invasive adenocarcinoma (MIA) and invasive adenocarcinoma (IAC) in patients who manifested as ground glass nodules (GGNs) or mixed GGNs (mGGNs) in unenhanced CT imaging.

The unenhanced and enhanced CT images of 194 patients with GGNs in the lung were retrospectively analyzed, including 64 cases with pre-invasive lesions, 80 cases with MIA, and 50 cases with IAC. The prediction of pathological types was based on maximal diameters and the solid portions of the lesions displayed on unenhanced and enhanced CT images, and then compared with pathological diagnosis.

In 64 patients with pre-invasive lesions, the CT value increased in 59 cases after contrast-enhanced administration, whereas the solid portions increased in 5 cases. In the 80 patients with MIA, solid portions increased in 50 cases and the CT value increased in 30 cases after contrast administration. In 50 cases with IAC, almost all of them showed increased solid portions, whereas only 2 cases showed an increase of CT values. In the pre-invasive group and the MIA group, the increase of CT values after contrast administration was (45.88±15.97) HU and (66.47±44.54) HU, respectively, showing statistically significant difference (P=0.001). The increase of solid portions in the MIA group and IAC group was (1.55±0.73) mm and (1.88±0.75) mm, respectively, also showing significant difference (P=0.032).

Contrast-enhanced CT scans were more useful than unenhanced CT scans for the diagnosis of lung adenocarcinomas manifesting as GGNs .

Lung neoplasms; Adenocarcinoma; Minimal invasive adenocarcinoma; Invasive adenocarcinoma; Computered tomography; Enhancement