title: Discordance between labelled white blood cell scintigraphy and bone scan following suspicion of bone infection: what should be done about it?
abstract: BACKGROUND
  Bone infection is a common issue in infectiology. The gold standard for evaluating bone infection is the white blood cell (WBC) scan. In our practice the WBC scan is coupled with a bone scan. Discordances in the results of these two examinations are a common occurrence in daily practice. We decided to investigate the meaning of these discordances.
  
  
  METHODS
  Two hundred and ninety-six 99mTc-HMPA labelled white blood cells (WBC) and 99mTc-HMDP bone scanning (BS) examinations were performed in our department between 1997 and 2003 for evaluation of bone infection. Out of these 296 examinations, a first rating extracted 54 scans that were considered discordant. These 54 scans were reviewed by three observers. Clinical and paraclinical data were obtained for all the cases definitely considered as discordant by all three observers.
  
  
  RESULTS
  The observers finally retained 18 cases as discordant from the initial 296 (6.1%). Thirteen patients were not infected,and five patients were considered infected based on clinical follow-up or bacteriological and histological data. For the 17 patients with WBC-, BS+, 4 (23.5%) were infected.
  
  
  CONCLUSIONS
  Our study shows that in the vast majority(17 out of 18), discordances consist of a negative WBC scan with a positive bone scan. In these cases the accuracy of the WBC scan is diminished as 23.5% of the patients with a negative WBC and a positive bone scan are infected.
authors.affiliation: Nuclear Medicine Department, Purpan Hospital, Toulouse, France. thomwagner@hotmail.com
authors.forename: Thomas
authors.initials: T
authors.lastname: Wagner
authors.forename: Pierre
authors.initials: P
authors.lastname: Payoux
authors.forename: Jacques
authors.initials: J
authors.lastname: Simon
authors.forename: Julian
authors.initials: J
authors.lastname: Anne
authors.forename: Mathieu
authors.initials: M
authors.lastname: Tafani
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Esquerré
authors.forename: Eric
authors.initials: E
authors.lastname: Bonnet
mesh_terms: D001850:Bone Diseases, Infectious / Q000097:blood* / Q000000981:diagnostic imaging*; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D005188:False Negative Reactions; D006801:Humans; D007962:Leukocytes / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D013194:Staining and Labeling; D019690:Technetium Tc 99m Exametazime; D013669:Technetium Tc 99m Medronate / Q000031:analogs & derivatives
chemical_list: D019690:Technetium Tc 99m Exametazime; C024226:technetium Tc 99m hydroxymethylene diphosphonate; D013669:Technetium Tc 99m Medronate