Dual-time-point FDG PET for the evaluation of locoregional lymph nodes in thoracic esophageal squamous cell cancer.

PURPOSE: Compare dual-time-point and single-time 18F-FDG PET in the evaluation of locoregional lymph node metastases in patients with esophageal squamous cell cancer. Then assess the efficacy of dual-time-point PET in the diagnosis of such nodules.

METHODS: 34 patients with thoracic esophageal squamous cell cancer underwent dual-time-point PET before surgery. Semi-quantitative analysis was performed using the standardized uptake value (SUV), obtained from early and delayed images (SUVearly and SUVdelayed, respectively). The retention index (RI) calculated according to the equation: (SUVdelayed-SUVearly) x 100/SUVearly was assessed. Results were compared prospectively in relation to pathologic findings.

RESULTS: 71 of 354 resected nodal groups from 28 patients were confirmed positive by pathology. SUVearly of 2.5 and RI of 10 were chosen as arbitrary cutoffs for differentiating malignancy from benign, the sensitivity, specificity, accuracy, negative and positive predictive value of dual-time-point PET were 88.73% (63/71 nodal groups), 91.87% (260/283), 91.24% (323/354), 97.01% (260/268) and 73.25% (63/86) respectively, those of single-time were 76.06% (54/71), 85.16% (241/283), 83.33% (295/354), 93.41% (241/258) and 56.25% (54/96) respectively. P values were 0.047, 0.012, 0.002, 0.052 and 0.017 respectively, indicating remarkable differences in sensitivity, specificity, accuracy, and positive predictive value between dual-time-point and single-time PET.

CONCLUSION: Dual-time-point 18F-FDG PET has the potential for improving the sensitivity, specificity, accuracy and positive predictive value in the evaluation of locoregional lymph nodes in thoracic esophageal squamous cell cancer.