title: 3D skeletal uptake of18F sodium fluoride in PET/CT images is associated with overall survival in patients with prostate cancer.
abstract: BACKGROUND
  Sodium fluoride (NaF) positron emission tomography combined with computer tomography (PET/CT) has shown to be more sensitive than the whole-body bone scan in the detection of skeletal uptake due to metastases in prostate cancer. We aimed to calculate a 3D index for NaF PET/CT and investigate its correlation to the bone scan index (BSI) and overall survival (OS) in a group of patients with prostate cancer.
  
  
  METHODS
  NaF PET/CT and bone scans were studied in 48 patients with prostate cancer. Automated segmentation of the thoracic and lumbar spines, sacrum, pelvis, ribs, scapulae, clavicles, and sternum were made in the CT images. Hotspots in the PET images were selected using both a manual and an automated method. The volume of each hotspot localized in the skeleton in the corresponding CT image was calculated. Two PET/CT indices, based on manual (manual PET index) and automatic segmenting using a threshold of SUV 15 (automated PET15index), were calculated by dividing the sum of all hotspot volumes with the volume of all segmented bones. BSI values were obtained using a software for automated calculations.
  
  
  RESULTS
  BSI, manual PET index, and automated PET15index were all significantly associated with OS and concordance indices were 0.68, 0.69, and 0.70, respectively. The median BSI was 0.39 and patients with a BSI >0.39 had a significantly shorter median survival time than patients with a BSI <0.39 (2.3 years vs not reached after 5 years of follow-up [p = 0.01]). The median manual PET index was 0.53 and patients with a manual PET index >0.53 had a significantly shorter median survival time than patients with a manual PET index <0.53 (2.5 years vs not reached after 5 years of follow-up [p < 0.001]). The median automated PET15index was 0.11 and patients with an automated PET15index >0.11 had a significantly shorter median survival time than patients with an automated PET15index <0.11 (2.3 years vs not reached after 5 years of follow-up [p < 0.001]).
  
  
  CONCLUSIONS
  PET/CT indices based on NaF PET/CT are correlated to BSI and significantly associated with overall survival in patients with prostate cancer.
authors.affiliation: Department of Translational Medicine, Lund University, Malmö, Sweden. sarah.lindgren_belal@med.lu.se.
authors.forename: Sarah
authors.initials: S
authors.lastname: Lindgren Belal
authors.affiliation: Department of Clinical Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
authors.forename: May
authors.initials: M
authors.lastname: Sadik
authors.affiliation: Department of Clinical Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
authors.forename: Reza
authors.initials: R
authors.lastname: Kaboteh
authors.affiliation: Department of Clinical Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
authors.forename: Nezar
authors.initials: N
authors.lastname: Hasani
authors.affiliation: Department of Signals and Systems, Chalmers University of Technology, Göteborg, Sweden.
authors.forename: Olof
authors.initials: O
authors.lastname: Enqvist
authors.affiliation: Eigenvision AB, Malmö, Sweden.
authors.forename: Linus
authors.initials: L
authors.lastname: Svärm
authors.affiliation: Department of Signals and Systems, Chalmers University of Technology, Göteborg, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Kahl
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark.
authors.forename: Jane
authors.initials: J
authors.lastname: Simonsen
authors.affiliation: Department of Urology, Odense University Hospital, Odense, Denmark.
authors.forename: Mads H
authors.initials: MH
authors.lastname: Poulsen
authors.affiliation: Department of Astronomy and Theoretical Physics, Lund University, Lund, Sweden.
authors.forename: Mattias
authors.initials: M
authors.lastname: Ohlsson
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark.
authors.forename: Poul F
authors.initials: PF
authors.lastname: Høilund-Carlsen
authors.affiliation: Department of Clinical Physiology, Sahlgrenska University Hospital, Göteborg, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Edenbrandt
authors.affiliation: Department of Translational Medicine, Lund University, Malmö, Sweden.
authors.forename: Elin
authors.initials: E
authors.lastname: Trägårdh
keywords: Bone scan index; Imaging biomarker; PET/CT; Prostate cancer; Sodium fluoride