title: FDG uptake in vaginal tampons is caused by urinary contamination and related to tampon position.
abstract: OBJECTIVE
  The aim of the study was to determine the aetiology of FDG uptake in vaginal tampons (VT), a known artefact in premenopausal women evaluated by PET/CT.
  
  
  METHODS
  This Institutional Review Board approved study consisted of retrospective and prospective parts. The retrospective analysis included 685 women examined between January 2008 and December 2009 regarding VT presence. PET/CT images were analysed to determine the localization and the standardized uptake value (SUV) of VTs. We prospectively recruited 24 women (20-48 years old) referred for staging or follow-up in an oncology setting between February and April 2010, who were provided a commercial VT to be used during the entire examination after obtaining written informed consent. After image acquisition, VTs were individually analysed for creatinine concentration and blood traces. Statistical significance was tested with the Mann-Whitney U test.
  
  
  RESULTS
  In the retrospective part, 38 of 685 women were found to have a VT of which 17 (45%) were FDG positive. A statistically significant correlation was found between FDG activity and VT position below the pubococcygeal line (PCL) (13 ± 11.2 mm). In the prospective study, 7 of 24 (29%) women had increased FDG activity in their VTs (SUV 18.8 ± 11 g/ml) but were not menstruating. FDG-positive VTs were significantly lower in position (14.6 ± 11.4 mm,below the PCL) than FDG-negative VTs (p = 0.039). The creatinine concentration was significantly increased in all seven positive VTs (931 ± 615 μmol/l).
  
  
  CONCLUSIONS
  FDG uptake in VTs is caused by urine contamination, which is likely related to localization below the PCL resulting in contact with urine during voiding.
authors.affiliation: Division of Nuclear Medicine, Department of Medical Radiology, University Hospital of Zurich, Ramistr. 100, 8091, Zurich, Switzerland. irene.burger@usz.ch
authors.forename: Irene A
authors.initials: IA
authors.lastname: Burger
authors.forename: David A
authors.initials: DA
authors.lastname: Scheiner
authors.forename: David W
authors.initials: DW
authors.lastname: Crook
authors.forename: Valerie
authors.initials: V
authors.lastname: Treyer
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Hany
authors.forename: Gustav K
authors.initials: GK
authors.lastname: von Schulthess
mesh_terms: D000328:Adult; D016477:Artifacts; D001692:Biological Transport; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D005547:Foreign Bodies; D006801:Humans; D008597:Menstrual Cycle; D052576:Menstrual Hygiene Products; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014556:Urine; D014621:Vagina / Q000378:metabolism; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18