title: Vascular inflammation imaging with 18F-FDG PET/CT: when to image?
abstract: We prospectively investigated the ideal imaging time to measure vascular uptake after injection of (18)F-FDG.
  
  
  METHODS
  A total of 17 patients with atherosclerotic abdominal aortic aneurysm underwent dynamic abdominal PET/CT using 2-min frames between 45 and 53, 57 and 65, 115 and 123, and 175 and 183 min after injection of (18)F-FDG. For each period of dynamic imaging, vessel wall and lumen uptake were measured using the maximum standardized uptake value (SUV(max)) and target-to-background ratio (TBR).
  
  
  RESULTS
  No significant difference in TBR across all time points (repeated measures ANOVA, P = 0.206) was observed, despite a significant difference in aortic wall and lumen uptake with time (repeated measures ANOVA, P = 0.02 and P < 0.001, respectively). There was no significant difference between aortic wall uptake at 60 min (SUV(max), 2.15 +/- 0.11 SE) and 180 min (SUV(max), 1.99 +/- 0.18 SE) (paired t test, P = 0.367). There was a significant difference in lumen uptake at 60 min (SUV(max), 2.4 +/- 0.11 SE) and 180 min (SUV(max), 1.7 +/- 0.1 SE) (paired t test, P = 0.001). There was no significant difference in TBR between 60 min (0.91 +/- 0.03) and 180 min (1.01 +/- 0.06 SE) (paired t test, P = 0.131). With increasing delayed imaging, there was increasing variability (SE) in the SUV(max) for the aortic wall and TBRs.
  
  
  CONCLUSIONS
  There was no significant advantage in imaging at 3 h over 1 h after (18)F-FDG injection.
authors.affiliation: Institute of Nuclear Medicine, University College Hospital, University College London, London, United Kingdom.
authors.forename: Leon J
authors.initials: LJ
authors.lastname: Menezes
authors.forename: Carl W
authors.initials: CW
authors.lastname: Kotze
authors.forename: Brian F
authors.initials: BF
authors.lastname: Hutton
authors.forename: Raymondo
authors.initials: R
authors.lastname: Endozo
authors.forename: John C
authors.initials: JC
authors.lastname: Dickson
authors.forename: Ian
authors.initials: I
authors.lastname: Cullum
authors.forename: Syed W
authors.initials: SW
authors.lastname: Yusuf
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ell
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Groves
mesh_terms: D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging; D050197:Atherosclerosis / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18