Dual-time-point F-18 FDG PET/CT for evaluation of intrathoracic lymph nodes in patients with non-small cell lung cancer.

ABSTRACT

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.