title: Utility of 11C-Methionine and 18F-FDG PET/CT in Patients With Functioning Pituitary Adenomas.
abstract: OBJECTIVE
  MRI is commonly used in the evaluation of pituitary adenomas (PAs). However, it has difficulty to locate the lesions sometimes, especially microadenomas and/or postoperative recurrent tumors. We aimed to evaluate the role of combined C-methionine (MET) and F-FDG PET/CT in patients with functioning PAs.
  
  
  METHODS
  This study included 43 patients: 15 had Cushing disease, 16 had acromegaly, and 12 had a prolactinoma. F-FDG PET/CT was performed on all of the patients; C-MET PET/CT was performed on 39 of the patients. The PET images and surgical findings were analyzed.
  
  
  RESULTS
  On F-FDG PET/CT, 29 (67%) of 43 cases had positive results, all of which were true positives, including 2 cases with equivocal MRI results. On C-MET PET/CT, 37 (95%) of 39 cases had positive results, of which 2 were false positives. All patients underwent surgery, and the results of PET/CT scans were confirmed by surgery and pathological examination. All F-FDG PET/CT results were negative when C-MET PET/CT results were negative. However, 12 patients with positive C-MET PET/CT results had negative F-FDG PET/CT results. The positive rate of F-FDG PET/CT in patients with somatostatin analog treatment, radiosurgery, transsphenoidal surgery, and microadenoma was 63% (5/8), 50% (1/2), 33% (4/12), and 48%(10/21), respectively, while that of C-MET PET/CT was 86% (6/7), 50% (1/2), 100% (12/12), and 100% (21/21), respectively. In the 9 patients with a recurrent microadenoma, the positive rate of F-FDG PET/CT was as low as 22% while that of C-MET PET/CT was 100%. There was no significant difference in the positive rate of C-MET and F-FDG PET/CT between the 3 types of PA.
  
  
  CONCLUSIONS
  PET/CT may be useful to detect tumors in patients with equivocal MRI results. C-MET PET/CT can provide valuable diagnostic information when F-FDG PET/CT yields negative results, especially in patients with recurrent microadenomas.
authors.affiliation: From the Departments of *Neurosurgery and Pituitary Tumor Center, and ‡Nuclear Medicine, The First Affiliated Hospital; and †Department of Histology and Embryology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
authors.forename: Zize
authors.initials: Z
authors.lastname: Feng
authors.forename: Dongsheng
authors.initials: D
authors.lastname: He
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Mao
authors.forename: Zongming
authors.initials: Z
authors.lastname: Wang
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Zhu
authors.forename: Xiangsong
authors.initials: X
authors.lastname: Zhang
authors.forename: Haijun
authors.initials: H
authors.lastname: Wang
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging* / Q000473:pathology; D000328:Adult; D000368:Aged; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008715:Methionine; D008875:Middle Aged; D064847:Multimodal Imaging; D010911:Pituitary Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D008715:Methionine