Integrated PET/CT of pulmonary neuroendocrine tumors: diagnostic and prognostic implications.

OBJECTIVE: The purpose of this study was to describe retrospectively integrated PET/CT findings on pulmonary neuroendocrine tumors and to correlate the findings with prognosis.

MATERIALS AND METHODS: Between May 2003 and February 2005, 37 consecutively enrolled patients (33 men and four women; mean age, 60 years) with histopathologically proven pulmonary neuroendocrine tumors underwent 18F-FDG PET/CT after enhanced standalone CT. CT was used to analyze the morphologic features of the tumors and PET to measure maximum standardized uptake value (SUV). Maximum SUVs of carcinoid tumors, large-cell neuroendocrine carcinomas (LCNECs), and small-cell lung carcinomas (SCLCs) were compared, and maximum SUV and tumor stage and prognosis were correlated.

RESULTS: Four (two typical and two atypical) of the seven carcinoid tumors had no FDG uptake or less than mediastinal uptake. The maximum SUVs of primary tumors, in increasing order, were significantly different for carcinoids (mean, 4.0; median, 3.4), LCNECs (mean, 12.0; median, 10.7), and SCLCs (mean, 11.6; median, 11.7) (p = 0.006, Kruskal-Wallis test). There was no significant correlation between maximum SUV of the primary tumor and the tumor stages of carcinoids, LCNECs, or SCLCs (p = 0.08, Jonckheere-Terpstra test; p = 0.768, Mann-Whitney test). Results of receiver operating characteristics analysis showed a maximum SUV greater than 13.7 suggested a poor survival period in cases of LCNEC and SCLC.

CONCLUSION: The maximum SUVs of neuroendocrine tumors are significantly different for carcinoid tumors, LCNECs, and SCLCs, and a high maximum SUV suggests short survival of patients with LCNEC or SCLC.