Dual-Time-Point F-18 FDG PET/CT for Evaluation of Intrathoracic Lymph Nodes in Patients With Non-Small Cell Lung Cancer

Purpose: The aim of this study was to evaluate the diagnostic capacity of F-18 fluorodeoxyglucose dual-time-point (DTP) positron emission tomography (PET)/computed tomography (CT) for intrathoracic lymph node (LN) metastases in patients with nonsmall cell lung cancer (NSCLC). Materials and Methods: Thirty-four patients had DTP PET/CT, with 60 minutes and 2-hour scans (n = 19, NSCLC; n = 15, benign pulmonary disease). LN diagnoses were confirmed by surgery or clinical follow-up (n = 14, metastatic LNs; n = 45, nonmetastatic LNs; n = 39, inflammatory LNs). Results: The maximum standardized uptake value (SUVmax) in the metastatic group was significantly higher than those in the nonmetastatic and inflammatory groups on both early- and delayed-phase imaging (each P < 0.0001). The retention index (RI) of SUVmax (RI-SUVmax) in the metastatic group was significantly higher than in the nonmetastatic (P = 0.0008) and inflammatory groups (P = 0.0074). No significant difference was found between SUVmax values of the nonmetastatic and inflammatory groups on early- (P = 0.6461) or delayed-phase (P =0.6913), or between RI-SUVmax values of the nonmetastatic and inflammatory groups (P = 0.5717). For early-phase SUVmax, the cut-off value for highest accuracy with metastatic LNs was 3.61, yielding a sensitivity of 86.67% and a specificity of 88.00%. For delayed-phase SUVmax, the cut-off value was 4.00, yielding a sensitivity of 91.6% and specificity of 92.9%. For RI-SUVmax, the cut-off value was 20.91%, yielding a sensitivity of 73.6% and specificity of 75.9%. Conclusions: DTP PET/CT with a semiquantitative technique may improve diagnostic capacity for nodal staging of NSCLC.