title: Staging and functional characterization of pheochromocytoma and paraganglioma by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography.
abstract: BACKGROUND
  Pheochromocytomas and paragangliomas (PPGLs) are rare tumors of the adrenal medulla and extra-adrenal sympathetic chromaffin tissues; their anatomical and functional imaging are critical to guiding treatment decisions. This study aimed to compare the sensitivity and specificity of (18)F-fluorodeoxyglucose positron emission tomography with computed tomography ((18)F-FDG PET/CT) for tumor localization and staging of PPGLs with that of conventional imaging by [(123)I]-metaiodobenzylguanidine single photon emission CT ((123)I-MIBG SPECT), CT, and magnetic resonance imaging (MRI).
  
  
  METHODS
  A total of 216 patients (106 men, 110 women, aged 45.2 ± 14.9 years) with suspected PPGL underwent CT or MRI, (18)F-FDG PET/CT, and (123)I-MIBG SPECT/CT. Sensitivity and specificity were measured as endpoints and compared by the McNemar test, using two-sided P values only.
  
  
  RESULTS
  Sixty (28%) of patients had nonmetastatic PPGL, 95 (44%) had metastatic PPGL, and 61 (28%) were PPGL negative. For nonmetastatic tumors, the sensitivity of (18)F-FDG was similar to that of (123)I-MIBG but less than that of CT/MRI (sensitivity of (18)F-FDG = 76.8%; of (123)I-MIBG = 75.0%; of CT/MRI = 95.7%; (18)F-FDG vs (123)I-MIBG: difference = 1.8%, 95% confidence interval [CI] = -14.8% to 14.8%, P = .210; (18)F-FDG vs CT/MRI: difference = 18.9%, 95% CI = 9.4% to 28.3%, P < .001). The specificity was 90.2% for (18)F-FDG, 91.8% for (123)I-MIBG, and 90.2% for CT/MRI. (18)F-FDG uptake was higher in succinate dehydrogenase complex- and von Hippel-Lindau syndrome-related tumors than in multiple endocrine neoplasia type 2 (MEN2) related tumors. For metastases, sensitivity was greater for (18)F-FDG and CT/MRI than for (123)I-MIBG (sensitivity of (18)F-FDG = 82.5%; of (123)I-MIBG = 50.0%; of CT/MRI = 74.4%; (18)F-FDG vs (123)I-MIBG: difference = 32.5%, 95% CI = 22.3% to 42.5%, P < .001; CT/MRI vs (123)I-MIBG: difference = 24.4%, 95% CI = 11.3% to 31.6%, P < .001). For bone metastases, (18)F-FDG was more sensitive than CT/MRI (sensitivity of (18)F-FDG = 93.7%; of CT/MRI = 76.7%; difference = 17.0%, 95% CI = 4.9% to 28.5%, P = .013).
  
  
  CONCLUSIONS
  Compared with (123)I-MIBG SPECT and CT/MRI, both considered gold standards for PPGL imaging, metastases were better detected by (18)F-FDG PET. (18)F-FDG PET provides a high specificity in patients with a biochemically established diagnosis of PPGL.
authors.affiliation: Department of Endocrinology and Department of Laboratory Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands.
authors.forename: Henri J L M
authors.initials: HJ
authors.lastname: Timmers
authors.forename: Clara C
authors.initials: CC
authors.lastname: Chen
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Carrasquillo
authors.forename: Millie
authors.initials: M
authors.lastname: Whatley
authors.forename: Alexander
authors.initials: A
authors.lastname: Ling
authors.forename: Graeme
authors.initials: G
authors.lastname: Eisenhofer
authors.forename: Kathryn S
authors.initials: KS
authors.lastname: King
authors.forename: Jyotsna U
authors.initials: JU
authors.lastname: Rao
authors.forename: Robert A
authors.initials: RA
authors.lastname: Wesley
authors.forename: Karen T
authors.initials: KT
authors.lastname: Adams
authors.forename: Karel
authors.initials: K
authors.lastname: Pacak
mesh_terms: D019797:3-Iodobenzylguanidine; D000310:Adrenal Gland Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D000328:Adult; D003287:Contrast Media; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D009367:Neoplasm Staging; D010235:Paraganglioma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D010673:Pheochromocytoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods; D012372:ROC Curve; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D019797:3-Iodobenzylguanidine