Résumé
Objective To investigate the value of 18 F-fluorodeoxyglucose (18 FDG)positron emission tomography and computer tomography (PET/CT)in the diagnosis and localization of ectopic ACTH syndrome (EAS)induced by lung cancer,and to increase the accuracy rate of diagnosis of EAS.Methods 8 patients were histopathologically proven to be lung cancer.18 FDG PET/CT wholebody and brain scan were performed;magnetic resonance imaging (MRI),99m Tc-octreotide (OCT)imaging and inferior petrosal sinus sampling (IPSS)were done in all patients.On 18 FDG PET/CT images,the SUVmax values of lesions and the SUVmax ratio of lesion tissue to normal lung tissue were calculated.Results ① 8 patients with EAS included 2 cases of carciniod,4 cases of atypical carciniod,and 2 cases of small cell lung cancer.The ACTH levels in inferior petrosal sinus and peripheral veins of 8 patients had no difference.②The chest CT showed there were pulmonary nodules in 6 cases (75%),among them 2 cases were atypical lesions.5 cases of pituitary adenomas were found by MRI (25%),and OCT imaging was positive in 2 cases (25%).③The 18 FDG PET/CT showed nodular,mass like or patch samples with high metabolic activity in 8 cases (100%)of pulmonary lesions.The SUVmax of tumor was 0.72 to 14.05 (3.67±4.68),and the ratio of SUVmax of lesion tissue to normal lung tissue was 1.69 to 27.54 (8.14 ± 9.63).18 FDG hypermetabolism was found in 8 cases of bilateral adrenal hyperplasia,while 4 cases showed pituitary tumor.Conclusion Lung cancer is a common source of EAS,especially carcinoid.18 FDG PET may show lower glucose metabolism.18 FDG PET/CT should be used as an assisted method to diagnose EAS.