Diagnostic performances of 68Ga-DOTATOC versus 18Fluorodeoxyglucose positron emission tomography in pulmonary carcinoid tumours and interrelationship with histological features

Few data are available about radio-receptorial positron emission tomography (PET) results by the use of 68Ga-DOTA-peptides in pulmonary carcinoid tumours. In this study, we retrospectively analysed 68Ga-DOTATOC/PET and 18Fluorodeoxyglucose (FDG) PET diagnostic performances in 62 pulmonary carcinoids (occurring in 57 patients) and interrelationship with histological features. All patients underwent at least 1 PET/computed tomography: 26 patients received 68Ga-DOTATOC, 52 patients had 18F-FDG and 20 patients received both techniques. There were 55 typical carcinoids and 7 atypical carcinoids. 68Ga-DOTATOC/PET recorded an 88.4% overall detection rate (DR) (meanSUVmax: 15.5); 18F-FDG/PET a DR of 53.8% (meanSUVmax: 3.2). When adopted a maximum standardized uptake value-threshold of 1.5, DRs of 68Ga-DOTATOC and 18F-FDG/PET increased to 100% and 80.8%, respectively. Moreover, DRs in both techniques vary considerably according to histology with 68Ga-DOTATOC/PET having better performances in typical carcinoids than in atypical carcinoids (DR: 91.7% vs 50.0%, P = 0.076). We also observed a significant correlation between a low number of mitoses (<2/10 high-power field) and 68Ga-DOTATOC/PET-positivity (P = 0.004), and an association trend (P = 0.076) between necrosis and 68Ga-DOTATOC/PET-negativity. In conclusion, 68Ga-DOTATOC had better diagnostic performances than 18F-FDG/PET in detecting pulmonary carcinoids. DRs of both techniques remarkably varied according to histology with 68Ga-DOTATOC/PET performing at its best in typical carcinoids, whereas 18F-FDG/PET did the same in atypical carcinoids.68Ga-DOTATOC/PET results were presumably associated with the number of mitoses and the presence of necrosis.