Receiver operating characteristic curves illustrating the ability of (A) SUVmax, (B) whole tumor size, and (C) solid tumor size to predict occult lymph node metastasis in patients with peripheral clinical stage I lung adenocarcinoma. The areas under the curves for SUVmax, whole tumor size, and solid tumor size are (A) 0.783 (95% CI: 0.702–0.865), (B) 0.707 (95% CI: 0.609–0.805), and (C) 0.791 (95% CI: 0.695–0.887), respectively. The optimal cutoff points are: (A) 3.45 for SUVmax, (B) 2.35 cm for whole tumor size, and (C) 2.35 cm for solid tumor size. SUVmax, maximal standardized uptake value; AUC, area under the curve; CI, confidence interval.