title: Pancreatic neuroendocrine tumors: diagnosis with PET.
abstract: OBJECTIVE
  To evaluate the use of carbon-11-labeled L-dihydroxyphenylalanine (L-DOPA) and hydroxytryptophan (5-HTP) in the diagnosis of pancreatic endocrine tumors with positron emission tomography (PET).
  
  
  METHODS
  Twenty-two consecutive patients with clinically and biochemically verified pancreatic endocrine tumors were examined with computed tomography (CT) and PET with L-DOPA alone (n = 16) or both C-11-L-DOPA and C-11-5-HTP (n = 6).
  
  
  RESULTS
  Tumor uptake of L-DOPA was found in 11 patients, eight of whom had metastatic disease. Heterogeneity of tracer uptake was noted among different lesions in the same patient (ie, high uptake in some lesions and low uptake in others). Results in patients examined with both L-DOPA and 5-HTP correlated well, but the uptake levels of 5-HTP were higher in two of three patients with positive findings. In two additional patients, CT enabled detection of tumors not detected at PET.
  
  
  CONCLUSIONS
  The current PET technique can be a valuable complement to CT in demonstration of functional pancreatic endocrine tumors, in particular, glucagonomas, but is less useful in detection of nonfunctional tumors.
authors.affiliation: Department of Diagnostic Radiology, University Hospital, Uppsala, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Ahlström
authors.forename: B
authors.initials: B
authors.lastname: Eriksson
authors.forename: M
authors.initials: M
authors.lastname: Bergström
authors.forename: P
authors.initials: P
authors.lastname: Bjurling
authors.forename: B
authors.initials: B
authors.lastname: Långström
authors.forename: K
authors.initials: K
authors.lastname: Oberg
mesh_terms: D007516:Adenoma, Islet Cell / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D002250:Carbon Radioisotopes; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007980:Levodopa; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging*; D012701:Serotonin; D014055:Tomography, Emission-Computed; D014057:Tomography, X-Ray Computed
chemical_list: D002250:Carbon Radioisotopes; D012701:Serotonin; D007980:Levodopa