title: Comparison of early and delayed FDG PET for evaluation of biliary stricture.
abstract: OBJECTIVE
  We assessed whether delayed FDG PET imaging is more useful for the evaluation of biliary stricture in differential diagnosis of malignancy from benign disease.
  
  
  METHODS
  Thirty-seven patients who underwent FDG PET for differential diagnosis of the disease causing biliary stricture were included. FDG PET imaging was performed at 70+/-12 min (early) post FDG injection and repeated 188+/-27 min (delayed) after injection only in the abdominal region. Image analysis was performed with visual interpretation and using a semi-quantitative method if lesion was visible on the PET image. The semi-quantitative analysis using the standardized uptake value (SUV) was determined for both early and delayed images (SUVearly and SUVdelayed, respectively). The tumour-to-normal liver (T/L) ratio was also calculated.
  
  
  RESULTS
  The final diagnosis was cholangiocarcinoma in 29 and benign disease in eight patients. In cases of cholangiocarcinoma, visual analysis of FDG PET using the delayed images, improve the diagnosis with one more patient correctly identified. For early and delayed FDG PET, sensitivities were 82.8% and 86.2%, respectively; specificities were 87.5% for both; and accuracies were 83.8% and 86.5%, respectively. Both SUV and T/L ratio derived from delayed images were significantly higher than those derived from early images for cholangiocarcinoma (P<0.0002 and P<0.0001, respectively).
  
  
  CONCLUSIONS
  FDG PET could be useful for differential diagnosis of malignancy from benign disease in patients with biliary stricture. Especially, the delayed targeted FDG PET imaging can be recommended in those patients when early imaging is negative or equivalent, because of increased lesion uptake and increased lesion to background contrast ratio.
authors: Department of Radiology, Faculty of Medicine, Kagawa University, Japan. nisiyosi@kms.ac.jp
authors: Yoshihiro
authors: Y
authors: Nishiyama
authors: Yuka
authors: Y
authors: Yamamoto
authors: Naruhide
authors: N
authors: Kimura
authors: Akihiro
authors: A
authors: Miki
authors: Yasuhiro
authors: Y
authors: Sasakawa
authors: Hisao
authors: H
authors: Wakabayashi
authors: Motoomi
authors: M
authors: Ohkawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001649:Bile Duct Diseases / Q000000981:diagnostic imaging* / Q000209:etiology*; D001661:Biliary Tract Neoplasms / Q000150:complications* / Q000000981:diagnostic imaging*; D003251:Constriction, Pathologic / Q000000981:diagnostic imaging / Q000209:etiology; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18