Abstract:      Background and purpose: With characteristic but non-specific features, subsolid pulmonary nodules (SSPN) is closely associated with early lung cancer. This study aimed to estimate the imaging value of SSPN in stage ⅠA lung cancer, and summarized the radiological features of various SSPNs, retrospectively. Methods: The clinical data and imaging data of 405 patients with solitary pulmonary nodules (SPNs) from Apr. 2008 to Apr. 2014 at Fudan University Shanghai Cancer Center were collected. According to ground-glass opacity (GGO) proportion, SPNs were divided into 3 groups: pure ground-glass opacity (pGGO), mixed ground-glass opacity (mGGO) and solid nodule (SN). The malignant ratios were calculated based on the postoperatively pathological results. Besides, SSPNs were classified into stage ⅠA lung cancer group and benign lesions group aiming at identifying the differentiating computed tomography (CT) features. Results: Of the enrolled 405 SPN patients, there were 367 SSPNs (including 124 pGGOs and 243 mGGOs) whose incidence in stage ⅠA lung cancer group was significantly higher than those in benign group [95.9% (257/268) vs 80.3% (110/137), P<0.001]. The total malignant ratio of SSPN was 70.0% (257/367), mGGO had a higher malignant ratio (72.0%) than those of pGGO (66.1%) and SN (28.9%). The malignant SSPNs were frequently detected in upper lobe of middle-aged women with a higher incidence of irregular edge, spiculation, lobulation and pleural retraction than benign group (P<0.05). Conclusion: SSPN is one of the significantly malignant indicators, and mGGO has the highest malignant tendency. Senility, female, irregular edge, spiculation, lobulation, pleural retraction and pulmonary upper lobe distribution are demonstrated the significant discriminators from benign lesions.

Key words: Subsolid nodule, Ground-glass opacity, Stage ⅠA lung cancer, Imaging diagnosis