title: Characterization of hepatic tumors using [11C]metomidate through positron emission tomography: comparison with [11C]acetate.
abstract: BACKGROUND
  Using positron emission tomography (PET), we compared two tracers, [11C]metomidate ([11C]MTO) and [11C]acetate ([11C]ACE), for the characterization of hepatic tumors.
  
  
  METHODS
  Thirty-three patients underwent PET with [11C]MTO and [11C]ACE and magnetic resonance imaging (MRI). Based on the histology of the tumor biopsy, 14 patients had hepatocellular carcinoma (HCC), 9 patients had focal nodular hyperplasia (FNH), and 10 patients had other types of hepatic tumors. Tumor uptake was evaluated by calculating the maximum and mean standardized uptake value and tumor-to-liver ratio.
  
  
  RESULTS
  Altogether, 120 hepatic lesions (59 HCC, 18 FNH, 30 metastases of different primaries, 9 adenomas, and 4 regenerating nodules of liver cirrhosis) were detected by MRI. The overall tumor detection rate was slightly higher for [11C]MTO (39%) than for [11C]ACE (33%). [11C]ACE was more sensitive for HCC detection (50% versus 43%, respectively), whereas [11C]MTO was more sensitive for FNH detection (78% versus 44%, respectively). In HCC patients, the tumor grade correlated with [11C]ACE, but not with [11C]MTO. All of the patients with liver metastases, from various primary tumors (n = 10), were negative for both tracers.
  
  
  CONCLUSIONS
  Due to low sensitivity, [11C]MTO and [11C]ACE PET have only limited value in diagnosing hepatic tumors.
authors: Turku PET Centre, Turku University Hospital, University of Turku, Kiinamyllynkatu 4-8, Turku 20521, Finland. marko.seppanen@tyks.fi.
authors: Anne
authors: A
authors: Roivainen
authors: Alexandru
authors: A
authors: Naum
authors: Heikki
authors: H
authors: Nuutinen
authors: Rauli
authors: R
authors: Leino
authors: Heimo
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authors: Nurmi
authors: Kjell
authors: K
authors: Någren
authors: Riitta
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authors: Parkkola
authors: Johanna
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authors: Virtanen
authors: Markku
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authors: Kallajoki
authors: Harry
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authors: Kujari
authors: Jari
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authors: Ovaska
authors: Peter
authors: P
authors: Roberts
authors: Marko
authors: M
authors: Seppänen