title: Optimal 2-[(18)F]fluoro-2-deoxy-D-galactose PET/CT protocol for detection of hepatocellular carcinoma.
abstract: BACKGROUND
  Positron emission tomography (PET) with the liver-specific galactose tracer 2-[(18)F]fluoro-2-deoxy-D-galactose ((18)F-FDGal) may improve diagnosis of hepatocellular carcinoma (HCC). The aim of this study was to test which of three different (18)F-FDGal PET protocols gives the highest tumour-to-background (T/B) ratio on PET images and thus better detection of HCC tumours.
  
  
  METHODS
  Ten patients with a total of 15 hepatic HCC tumours were enrolled prior to treatment. An experienced radiologist defined volumes of interest (VOIs) encircling HCC tumours on contrast-enhanced CT (ce-CT) images. Three PET/CT protocols were conducted following an intravenous (18)F-FDGal injection: (i) a 20-min dynamic PET/CT of the liver (to generate a 3D metabolic image), (ii) a traditional static whole-body PET/CT after 1 h, and (iii) a late static whole-body PET/CT after 2 or 3 h. PET images from each PET/CT protocol were fused with ce-CT images, and the average standardized uptake values (SUV) in tumour and background liver tissue were used to calculate (T/B) ratios. Furthermore, Tpeak/B ratios were calculated using the five hottest voxels in all hot tumours. The ratios for the three different PET protocols were compared.
  
  
  RESULTS
  For the individual tumours, there was no significant difference in the T/B ratio between the three PET protocols. The metabolic image yielded higher Tpeak/B ratios than the two static images, but it was easier to identify tumours on the static images. One extrahepatic metastasis was detected.
  
  
  CONCLUSIONS
  Neither metabolic images nor static whole-body images acquired 2 or 3 h after (18)F-FDGal injection offered an advantage to traditional whole-body PET/CT images acquired after 1 h for detection of HCC.
authors.affiliation: Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, DK8000, Aarhus, Denmark.
authors.forename: Jacob
authors.initials: J
authors.lastname: Horsager
authors.affiliation: Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, DK8000, Aarhus, Denmark.
authors.forename: Kirstine
authors.initials: K
authors.lastname: Bak-Fredslund
authors.affiliation: Department of Radiology, Aarhus University Hospital, DK8000, Aarhus, Denmark.
authors.forename: Lars Peter
authors.initials: LP
authors.lastname: Larsen
authors.affiliation: Department of Hepatology & Gastroenterology, Aarhus University Hospital, Noerrebrogade 44 bldg. 7, DK8000, Aarhus C, Denmark.
authors.forename: Gerda Elisabeth
authors.initials: GE
authors.lastname: Villadsen
authors.affiliation: Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, DK8000, Aarhus, Denmark.|Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway.
authors.forename: Trond Velde
authors.initials: TV
authors.lastname: Bogsrud
authors.affiliation: Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, DK8000, Aarhus, Denmark. michsoer@rm.dk.|Department of Hepatology & Gastroenterology, Aarhus University Hospital, Noerrebrogade 44 bldg. 7, DK8000, Aarhus C, Denmark. michsoer@rm.dk.
authors.forename: Michael
authors.initials: M
authors.lastname: Sørensen
keywords: Dynamic PET; Galactose; Hepatocellular carcinoma; Metabolic clearance; Static PET