Objectives: The aim of this study was to conduct comparative analyses of the biological malignant potential of clinical stage IA adenocarcinoma using positron emission tomography/computed tomography (PET/CT), high-resolution CT (HRCT), and three-dimensional CT (3DCT). The predictive performance of these parameters was evaluated in terms of clinical outcomes and pathological invasiveness (positive lymphatic permeation, blood-vessel invasion, pleural invasion, and lymph-node metastasis). Materials and methods: We enrolled 170 patients with c-IA adenocarcinoma who underwent PET/CT, HRCT, and 3D reconstruction of lung structures using the Synapse Vincent system (Fujifilm Corporation, Tokyo, Japan) followed by complete resection. Maximum standardized uptake values (SUVmax) of F18-fluorodeoxyglucose and the size and volume of the solid part of the tumor were quantified and analyzed in relation to surgical outcomes. Results: Univariate analysis demonstrated that all the three parameters and whole-tumor volume were associated with unfavorable disease-free survival (DFS), while the volume of the solid part was the independent predictor on multivariate analysis (p &lt
.001). The receiver operating characteristic curves for pathological invasiveness, determined using the variables dichotomized at each cut-off level (SUVmax 2.4
solid-part size 1.23 cm
solid-part volume 779 mm3), showed that all were significantly correlated with pathological invasiveness and prognosis, whereas the combination of SUVmax and the solid-part volume was the most powerful predictor of survival and pathological invasiveness compared to any other parameters: the 4-year DFS and proportion of pathological invasiveness in patients with SUVmax &gt
2.4 and solid-part volume &gt
779 mm3 versus those with SUVmax ≤ 2.4 or solid-part volume ≤779 mm3 were 81.2% versus 98.3% (p &lt
.001) and 84.3% versus 15.1% (p &lt
.001), respectively. Conclusion: In c-IA adenocarcinoma, the volume of the solid part of the tumor was the independent predictor for unfavorable DFS, and the integration of the volume of the solid part and SUVmax was highly beneficial for the prediction of survival and pathological invasiveness.