title: Dual-time-point FDG PET/CT: Is It Useful for Lymph Node Staging in Patients with Non-Small-Cell Lung Cancer?
abstract: OBJECTIVE
  Dual-time-point (DTP) FDG PET/CT has been shown to be useful for lymph node (LN) staging in patients with non-small-cell lung cancer (NSCLC). The aim of this study was to evaluate the LN staging ability of DTP FDG PET/CT in the predominant area of pulmonary tuberculosis.
  
  
  METHODS
  Sixty-nine NSCLC patients underwent DTP PET/CT. Regions of interest were placed on each LN of each station, and the maximum SUVs were measured. Three variables were obtained: (1) the SUV on the early scan (SUVearly), (2) the SUV on the delayed scan (SUVdelayed), and (3) the retention index of the SUV (RI). Each patient had one final LN stage and three other LN stages according to the cutoff values of SUVearly, SUVdelayed, and RI.
  
  
  RESULTS
  In the LN-based analysis, the area under the ROC curve of SUVdelayed (0.884) was significantly larger (P < 0.01) than those of SUVearly (0.868) and RI (0.717). Among the three variables, SUVdelayed was more accurate (P < 0.01) for detecting the mediastinal LN metastasis than SUVearly and RI. In the patient-based analysis, SUVdelayed had correctly determined LN stages in 55 of 69 patients (sensitivity, specificity, and accuracy = 88.7 %, 50.0 %, and 79.7 %), whereas SUVearly and RI correctly determined LN stages in 53 and 52 patients, respectively.
  
  
  CONCLUSIONS
  In this study, comparing the diagnostic efficacy of SUVearly, SUVdelayed, and RI for LN staging in patients with NSCLC, SUVdelayed was the most accurate variable for LN staging. DTP PET/CT could provide improved diagnostic accuracy for the LN staging of NSCLC.
authors.affiliation: Department of Nuclear Medicine and Institute of Wonkwang Medical Science, Wonkwang University School of Medicine, 344-2 Shinyong-Dong, Iksan, Jeollabuk-do 570-711 Republic of Korea.
authors.forename: Dae-Weung
authors.initials: DW
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine and Institute of Wonkwang Medical Science, Wonkwang University School of Medicine, 344-2 Shinyong-Dong, Iksan, Jeollabuk-do 570-711 Republic of Korea.
authors.forename: Woo Hyoung
authors.initials: WH
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine and Institute of Wonkwang Medical Science, Wonkwang University School of Medicine, 344-2 Shinyong-Dong, Iksan, Jeollabuk-do 570-711 Republic of Korea.
authors.forename: Chang Guhn
authors.initials: CG
authors.lastname: Kim
keywords: Dual-time-point imaging; Fluorodeoxyglucose; Lymph node staging; Non-small-cell lung cancer; Positron emission tomography