A Comparison of ⁶⁸Ga-DOTATATE and ¹⁸F-FDG PET/CT in Pulmonary Neuroendocrine Tumors

Abstract

Our purpose was to compare the performance of ⁶⁸Ga-1,4,7,10-tetraazacyclododecane-N,N′,N″,N‴-tetraacetic acid-d-Phe¹,Tyr³-octreotate (DOTATATE), a novel selective somatostatin receptor 2 PET ligand, and ¹⁸F-FDG in the detection of pulmonary neuroendocrine tumors using PET/CT, with correlation of uptake and tumor grade on histology. Methods: The imaging findings of the first 18 consecutive patients (8 men and 10 women) with pulmonary neuroendocrine tumors (11 typical carcinoids, 2 atypical carcinoids, 1 large cell neuroendocrine tumor, 1 small cell neuroendocrine carcinoma, 1 non–small cell lung cancer with neuroendocrine differentiation, and 2 cases of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia) who underwent ⁶⁸Ga-DOTATATE and ¹⁸F-FDG PET/CT were reviewed. In all cases, the diagnosis was established on histology. Results: Of 18 patients, 15 had primary tumors (median size, 2.7 cm; range, 0.5–8 cm) and 3 had recurrent tumors. All typical carcinoids showed high uptake of ⁶⁸Ga-DOTATATE (maximum standardized uptake value [SUV_max] ≥ 8.2), but 4 of 11 showed negative or minimal ¹⁸F-FDG uptake (SUV_max = 1.7–2.9). All tumors of higher grade showed high uptake of ¹⁸F-FDG (SUV_max ≥ 11.7), but 3 of 5 showed only minimal accumulation of ⁶⁸Ga-DOTATATE (SUV_max = 2.2–2.8). Neither case of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia showed uptake of ⁶⁸Ga-DOTATATE or ¹⁸F-FDG. Typical carcinoids showed significantly higher uptake of ⁶⁸Ga-DOTATATE and significantly less uptake of ¹⁸F-FDG than did tumors of higher grade (P = 0.002 and 0.005). There was no instance of false-positive uptake of ⁶⁸Ga-DOTATATE, but there were 3 sites of ¹⁸F-FDG uptake secondary to inflammation. ⁶⁸Ga-DOTATATE was superior to ¹⁸F-FDG in discriminating endobronchial tumor from distal collapsed lung (P = 0.02). Conclusion: Typical bronchial carcinoids showed higher and more selective uptake of ⁶⁸Ga-DOTATATE than of ¹⁸F-FDG. Atypical carcinoids and higher grades had less ⁶⁸Ga-DOTATATE avidity but were ¹⁸F-FDG–avid.