title: 18F-fluorodeoxyglucose positron emission tomography features of idiopathic retroperitoneal fibrosis.
abstract: OBJECTIVE
  To evaluate the 18F-fluorodeoxyglucose (FDG) uptake features of idiopathic retroperitoneal fibrosis (IRF).
  
  
  METHODS
  18F-Fluorodeoxyglucose positron emission tomographic (PET) or PET/computed tomographic findings were retrospectively reviewed in 6 patients with IRF. FDG PET or PET/computed tomography was performed 1 and 2 hours after FDG injection. The FDG level was scored using a 4-point scale, and the intensity of FDG uptake was quantified using the maximum standardized uptake value (SUVmax).
  
  
  RESULTS
  In the 1-hours images, intense FDG uptake by IRF was observed in 5 patients before steroid treatment, but no abnormal uptake was noted in 1 patient receiving steroid treatment. The SUVmax in IRF increased from a mean +/- SD of 6.0 +/- 1.2 (range, 4.9-7.6) to 7.6 +/- 1.1 (range, 5.9-8.2) for all 4 patients who underwent 1 and 2 hours dual-time point imaging. Abnormal uptake was also noted in the mediastinum and the pancreas in 1 and 2 patients, and the diagnoses of mediastinal fibrosis and autoimmune pancreatitis were made, respectively. The SUVmax was stable or increased in the 3 lesions of mediastinal fibrosis and autoimmune pancreatitis.
  
  
  CONCLUSIONS
  FDG PET may be a reliable means of evaluating disease activity and the extent of IRF, but dual-time point imaging may not be useful to differentiate malignancy from IRF.
authors: Department of Radiology, Atsuchi Memorial Clinic PET Center, Kagoshima, Japan. toyo.nakajo@dolphin.ocn.ne.jp
authors: Masatoyo
authors: M
authors: Nakajo
authors: Seishi
authors: S
authors: Jinnouchi
authors: Hiroaki
authors: H
authors: Tanabe
authors: Rie
authors: R
authors: Tateno
authors: Masayuki
authors: M
authors: Nakajo
mesh_terms: D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000000981:diagnostic imaging; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D010195:Pancreatitis / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012185:Retroperitoneal Fibrosis / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18