Comparison of 18F-FDG and 68Ga-DOTATATE PET/CT in surgically treated lung carcinoid tumors

Aims: This study aims to compare the efficacy of FDG-18 PET/CT and 68Ga-DOTATATE PET/CT imaging techniques in patients with lung carcinoid tumors, identifying the most appropriate preoperative nuclear medicine technique for diagnosis and staging. Methods: We retrospectively analyzed data from 123 patients who underwent surgery for lung carcinoid tumors at our center between 2009 and 2021. All of the patients were scanned with FDG-18 PET/CT before surgery. In addition to FDG-18 PET/CT, 68Ga-DOTATATE PET/CT scanning was performed in 28 patients: 17 in the preoperative and 11 in the postoperative period. Demographic data, mean higher maximal standard uptake (SUVmax) values of primary mass, lymph nodes and extrathoracic foci, pathologic subtype, and type of surgery were recorded. Compliance with normal distribution for numerical data was assessed using the Shapiro-Wilk test. The Wilcoxon signed-rank test was employed for groups meeting normal distribution to compare continuous numerical variables. The Mann-Whitney U and Kruskal-Wallis tests were used when normal distribution assumptions were unsatisfied. Results: The mean SUVmax value in 68Ga-DOTATATE PET/CT was significantly higher than FDG-18 PET/CT in patients with a lung carcinoid tumor (20 vs 4.4). For 68Ga-DOTATATE PET/CT scan, typical carcinoids had higher mean SUVmax value than atypical carcinoids (26 and 5.6 respectively), and the difference was statistically significant (p=0.002). For that FDG18 PET/CT, on the contrary, the mean SUVmax value was higher in atypical carcinoids than typical carcinoids (5.4 and 3.8, respectively), and the difference was not significant (p=0.126) Conclusion: The SUVmax values from 68Ga-DOTATATE PET/CT and FDG-18 PET/CT in lung carcinoid tumors vary by tumor subtype. 68Ga-DOTATATE PET/CT demonstrates higher SUVmax values in typical carcinoid tumors, indicating its superiority over FDG-18 PET/CT for this subtype. Although 68Ga-DOTATATE PET/CT also shows elevated SUVmax in atypical carcinoid tumors, the difference compared to FDG-18 PET/CT does not reach statistical significance.