ObjectiveTo analyze the relationship between maximum standardized uptake value (SUVmax) of primary tumor detected by 18F-FDG positron emission tomography/computed tomography (PET/CT) and clinicopathologic factors in stageⅠnon-small cell lung cancer (NSCLC), and investigate the prognostic value of PET/CT on pathological feature. MethodsWe retrospectively analyzed clinical data of 182 patients with stageⅠNSCLC who underwent 18F-FDG PET/CT scan before lobectomy or segmentectomy in China-Japan Friendship Hospital from April 2013 to June 2014. There were 121 male and 61 female patients with their ages of 34-85 (68.1±9.8) years. Clinicopathologic factors including sex, age, smoking history, histology, TNM stage, T stage, tumor size, lymphatic vessel invasion, blood vessel invasion (BVI) and visceral pleural invasion were evaluated to identify the independent factors affecting SUVmax by univariate and multivariate regression analysis. The diagnostic efficiency and best cut-off point of SUVmax were calculated by the receiver operating characteristic curve. ResultsThe univariate analysis identified that sex (P=0.015), smoking history (P=0.001), histology (P < 0.001), TNM stage (P=0.004), T stage (P=0.001), tumor size (P < 0.001), BVI (P=0.001) were factors affecting SUVmax. Only histology (P=0.001), tumor size (P=0.006), BVI (P=0.009) were found to be significant independent factors according to multivariate regression analysis. The SUVmax of primary tumor was a predictor for BVI with the highest diagnostic accuracy at a cut-off value of 4.85, the sensitivity and specificity were 65.5% and 71.7%. ConclusionThe SUVmax is correlated with histology, tumor size and BVI in stageⅠNSCLC, higher in patients with non-adenocarcinoma, lager tumor and positive BVI. Furthermore, the probability of BVI could be predicted by SUVmax of the primary tumor.