title: Posterior bladder layering of excreted 18F-FDG on PET/CT.
abstract: OBJECTIVE
  This study was carried out to determine the frequency, characteristics and possible causes and clinical significance of occasionally observed posterior layering of excreted 2-deoxy-2-[F]fluoro-D-glucose (F-FDG) in the bladder.
  
  
  METHODS
  A review of 567 consecutive patients referred for positron emission tomography/computerized tomography studies was performed. Urinary bladder size was measured in patients with and without layering. Urine samples from two patients with layering were imaged ex vivo.
  
  
  RESULTS
  Twenty-four of 567 studies (4%) showed F-FDG posterior bladder layering. Mean volume+/-SD of the bladder was 175+/-161 ml in patients with layering and 93+/-83 ml in patients without layering. Urine samples collected from two randomly chosen patients with layering in vivo failed to show layering ex vivo.
  
  
  CONCLUSIONS
  Posterior F-FDG layering occurs in 4% of positron emission tomography/computerized tomography cases and highly correlates with bladder volume. The mechanism is hypothesized to be because of slow F-FDG excretion in patients with a distended urinary bladder resulting in delayed mixing with urine, but needs to be further investigated with a more comprehensive study.
authors.affiliation: Department of Radiology, Emory School of Medicine, Atlanta, Georgia, USA. Wanzhenzeng@gmail.com
authors.forename: Wanzhen
authors.initials: W
authors.lastname: Zeng
authors.forename: Julio N
authors.initials: JN
authors.lastname: Sepulveda
authors.forename: Jonathan
authors.initials: J
authors.lastname: Nye
authors.forename: John R
authors.initials: JR
authors.lastname: Votaw
authors.forename: Peter T
authors.initials: PT
authors.lastname: Nieh
authors.forename: John
authors.initials: J
authors.lastname: Carew
authors.forename: David M
authors.initials: DM
authors.lastname: Schuster
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D001743:Urinary Bladder / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D014556:Urine; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18