This study aimed to present a proper understanding of the fluorine-18-fluorodeoxyglucose (18F-FDG) PET/computed tomography (CT) value in localizing the primary lesion in adrenocorticotropic hormone (ACTH)-dependent Cushing syndrome in a relatively large case cohort.
This retrospective study included 47 patients with ACTH-dependent Cushing syndrome, who underwent an 18F-FDG PET/CT examination in our hospital from November 2010 to January 2018. The serum cortisol, 24 h urine cortisol, serum ACTH, and high-dose dexamethasone suppression test were measured in all the patients. Bilateral inferior petrosal sinus sampling was performed in 28/47 patients. Pituitary magnetic resonance imaging and whole-body 18F-FDG PET/CT were performed in all patients.
Serum ACTH at 8 a.m. higher than 161.8 pg/ml as the cut-off value showed the best diagnostic accuracy (73.9%) for the successful localization of the primary lesions. In Cushing disease patients, the pituitary maximum standardized uptake value 18F-FDG PET/CT (n=11) did not show significant differences compared with that in ectopic ACTH syndrome (EAS) patients (n=20). In terms of EAS, the descending order of maximum standardized uptake value was 13.2±8.3 (4.8–26.4) in pancreatic neuroendocrine tumors (n=4), 7.1±2.4 (3.5–10.1) in mediastinal carcinoid (n=11), and 2.0±0.1 (1.9–2.2) in bronchial carcinoid (n=4). This study first reported the 18F-FDG PET/CT images of ACTH-secreting olfactory neuroblastoma.
Serum ACTH level determines the success rate of localization of the primary ACTH-secreting tumor in ACTH-dependent syndrome. 18F-FDG PET/CT plays a role in localizing the site for EAS, although it plays a limited role in Cushing disease.
aDepartment of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine
bDepartment of Nuclear Medicine, Zhongshan Hospital, Fudan University, Shanghai, People’s Republic of China
Correspondence to Yifan Zhang, MD, PhD, Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, No. 197, Ruijin 2nd Road, Shanghai, 200025, People’s Republic of China Tel: +86 021 6431 4813; fax: +86 021 6433 3548; e-mail: firstname.lastname@example.org
Received November 26, 2018
Received in revised form January 7, 2019
Accepted January 20, 2019