Preinvasive and Invasive Lung Adenocarcinoma Appearing as Part-Solid Ground-Glass Nodules: Differentiation with CT Value and Solid-Part Diameter

Objective: To evaluate the differentiating roles of computed tomography (CT) for invasive adenocarcinomas (IACs) of the lung from preinvasive lesions or minimally invasive adenocarcinomas (MIAs) manifesting as part-solid ground-glass nodules (GGNs). Methods: All 230 lesions were pathologically confirmed, whose size, CT parameters and morphological features were compared among the three groups. Optimal cut-off values were calculated for parameters with diagnostic value. Results: The diameter of the GGN lesion and the maximum diameter of the solid part, as well as CT values of the ground-glass part and the solid part differed significantly among three groups. Cut-off maximum diameter of the solid part was 2.5 and 5.5 mm to differentiate preinvasive versus MIA and MIA versus IAC, respectively. Cut-off mean CT value was -581 and -464 HU to differentiate preinvasive versus MIA and MIA versus IAC, respectively. Cut-off CT value of the ground-glass part was -675 and -562 HU to differentiate the same three groups. Morphological characteristics such as lobulation, speculation and air bronchograms were all more likely to occur in invasive lesions. Conclusion: The mean CT value, CT value of the ground glass part and maximum solid-part diameter of a GGN can help differentiate preinvasive from invasive lung adenocarcinomas.