Our purpose was to compare the performance of 68 4,7,N9,N$,N%-tetraacetic acid-D-Phe 1 , Tyr 3 -octreotate (DOTATATE), a novel selective somatostatin receptor 2 PET ligand, and 18 F-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 68 Ga-DOTATATE and 18 F-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 68 Ga-DOTATATE (maximum standardized uptake value [SUV max ] $ 8.2), but 4 of 11 showed negative or minimal 18 F-FDG uptake (SUV max 5 1.7-2.9). All tumors of higher grade showed high uptake of 18 F-FDG (SUV max $ 11.7), but 3 of 5 showed only minimal accumulation of 68 Ga-DOTATATE (SUV max 5 2.2-2.8). Neither case of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia showed uptake of 68 Ga-DOTATATE or 18 F-FDG. Typical carcinoids showed significantly higher uptake of 68 Ga-DOTATATE and significantly less uptake of 18 F-FDG than did tumors of higher grade (P 5 0.002 and 0.005). There was no instance of falsepositive uptake of 68 Ga-DOTATATE, but there were 3 sites of 18 F-FDG uptake secondary to inflammation. 68 Ga-DOTATATE was superior to 18 F-FDG in discriminating endobronchial tumor from distal collapsed lung (P 5 0.02). Conclusion: Typical bronchial carcinoids showed higher and more selective uptake of 68 Ga-DOTATATE than of 18 F-FDG. Atypical carcinoids and higher grades had less 68 Ga-DOTATATE avidity but were 18 F-FDG-avid.

Neither (18)F-FDG nor (68)Ga-DOTATATE PET/CT can fully map the extent of disease in patients with recurrent MTC, although (18)F-FDG PET/CT may identify more lesions. However, (68)Ga-DOTATATE PET/CT can be a useful complementary imaging tool and may identify patients suitable for consideration of targeted radionuclide somatostatin analogue therapy.

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The diagnosis of lymphangiomatosis can often be made on clinical grounds with the aid of plain radiography. In children with intractable chylothorax computed tomography (CT) of the thorax may reveal the presence of a mediastinal mass but frequently in lymphangiomatosis will not demonstrate any specific features. Abdominal CT, on the other hand, may suggest the diagnosis by the association with intraabdominal lymphangioma.

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