title: Total lesion glycolysis as the best 18F-FDG PET/CT parameter in differentiating intermediate-high risk adrenal incidentaloma.
abstract: OBJECTIVE
  Characterization of intermediate-high risk adrenal incidentaloma (AI) is important because biopsy or surgery should be performed to confirm the malignancy. We investigated which parameters of F-fluorodeoxyglucose ((18)F-FDG) PET/computed tomography (CT) had an additive role in distinguishing malignancies in patients with incidental adrenal masses of intermediate-high risk.
  
  
  METHODS
  From January 2008 to July 2013, 52 patients with a pathologically proven diagnosis of AI were retrospectively enrolled (age=56.4±12.7 years, M : F=34 : 18; benign : malignant=14 : 38). Volumetric parameters were size and volume according to combined CT, and metabolic parameters were peak standardized uptake value (SUV(peak)), maximum SUV (SUV(max)), mean SUV (SUV(mean)), and tumor-to-background ratio (SUV(max) of adrenal mass/SUV(mean) of liver). Metabolovolumetric parameters of metabolic tumor volume and total lesion glycolysis (TLG, SUV(mean)×metabolic tumor volume) were also included and compared with the diagnostic value. In addition, the highest diagnostic parameters among volumetric and metabolic parameters were combined and compared in terms of diagnostic accuracy.
  
  
  RESULTS
  Compared with benign adrenal adenoma, malignant lesions showed significantly higher values of all (18)F-FDG PET/CT volumetric, metabolic, and metabolovolumetric parameters. Size showed the highest area under the curve (AUC) of 0.759 among the volumetric parameters, and SUV(peak) showed the highest AUC of 0.853 among the metabolic parameters. Among all the PET/CT parameters, TLG showed the highest AUC of 0.900, with a sensitivity of 92.1% and specificity of 78.6% at a cutoff of 12.0. The combined value of size and SUV(peak) showed lower diagnostic value than TLG.
  
  
  CONCLUSIONS
  We found that TLG showed the best result in distinguishing intermediate-high risk AI among PET/CT parameters. TLG can be a useful PET/CT parameter for differential diagnosis of AI.
authors.affiliation: aDepartment of Nuclear Medicine bCancer Research Institute cRadiological Science Research Institute, Seoul National University College of Medicine dDepartment of Molecular Medicine and Biopharmaceutical Sciences, WCU Graduate School of Convergence Science and Technology, Seoul National University eDepartment of Radiology, Seoul National University Hospital, Seoul, Korea fDepartment of Radiological Sciences, University of California, Irvine, California, USA.
authors.forename: Yong-il
authors.initials: YI
authors.lastname: Kim
authors.forename: Gi Jeong
authors.initials: GJ
authors.lastname: Cheon
authors.forename: Jin Chul
authors.initials: JC
authors.lastname: Paeng
authors.forename: Jeong Yeon
authors.initials: JY
authors.lastname: Cho
authors.forename: Keon Wook
authors.initials: KW
authors.lastname: Kang
authors.forename: June-Key
authors.initials: JK
authors.lastname: Chung
authors.forename: Euishin Edmund
authors.initials: EE
authors.lastname: Kim
authors.forename: Dong Soo
authors.initials: DS
authors.lastname: Lee
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging; D000293:Adolescent; D000310:Adrenal Gland Neoplasms / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006019:Glycolysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D012372:ROC Curve; D012189:Retrospective Studies; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18