title: Diagnosing infection in the failed joint replacement: a comparison of coincidence detection 18F-FDG and 111In-labeled leukocyte/99mTc-sulfur colloid marrow imaging.
abstract: The objectives of this study were to investigate (18)F-FDG imaging, using a coincidence detection system, for diagnosing prosthetic joint infection and to compare it with combined (111)In-labeled leukocyte/(99m)Tc-sulfur colloid marrow imaging in patients with failed lower extremity joint replacements.
  
  
  METHODS
  Fifty-nine patients--with painful, failed, lower extremity joint prostheses, 40 hip and 19 knee--who underwent (18)F-FDG, labeled leukocyte, and bone marrow imaging, and had histopathologic and microbiologic confirmation of the final diagnosis, formed the basis of this investigation. (18)F-FDG images were interpreted as positive for infection using 4 different criteria: criterion 1: any periprosthetic activity, regardless of location or intensity; criterion 2: periprosthetic activity on the (18)F-FDG image, without corresponding activity on the marrow image; criterion 3: only bone-prosthesis interface activity, regardless of intensity; criterion 4: semiquantitative analysis--a lesion-to-background ratio was generated, and the cutoff value yielding the highest accuracy for determining the presence of infection was determined. Labeled leukocyte/marrow images were interpreted as positive for infection when periprosthetic activity was present on the labeled leukocyte image without corresponding activity on the marrow image.
  
  
  RESULTS
  Twenty-five (42%) prostheses, 14 hip and 11 knee, were infected. The sensitivity, specificity, and accuracy of (18)F-FDG, by criterion, were as follows: criterion 1: 100%, 9%, 47%; criterion 2: 96%, 35%, 61%; criterion 3: 52%, 44%, 47%; criterion 4: 36%, 97%, 71%. The sensitivity, specificity, and accuracy of labeled leukocyte/marrow imaging were 100%, 91%, and 95%, respectively. WBC/marrow imaging, which was more accurate than any of the (18)F-FDG criteria for all prostheses, as well as for hips and knees separately, was significantly more sensitive than criterion 3 (P < 0.001) and criterion 4 (P < 0.001) and was significantly more specific than criterion 1 (P < 0.001), criterion 2 (P < 0.001), and criterion 3 (P < 0.001).
  
  
  CONCLUSIONS
  Regardless of how the images are interpreted, coincidence detection-based (18)F-FDG imaging is less accurate than, and cannot replace, labeled leukocyte/marrow imaging for diagnosing infection of the failed prosthetic joint.
authors.affiliation: Division of Nuclear Medicine, Long Island Jewish Medical Center, New Hyde Park, New York 11040, USA.
authors.forename: Charito
authors.initials: C
authors.lastname: Love
authors.forename: Scott E
authors.initials: SE
authors.lastname: Marwin
authors.forename: Maria B
authors.initials: MB
authors.lastname: Tomas
authors.forename: Eugene S
authors.initials: ES
authors.lastname: Krauss
authors.forename: Gene G
authors.initials: GG
authors.lastname: Tronco
authors.forename: Kuldeep K
authors.initials: KK
authors.lastname: Bhargava
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Nichols
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Palestro
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001424:Bacterial Infections / Q000000981:diagnostic imaging; D001853:Bone Marrow / Q000000981:diagnostic imaging; D005260:Female; D019788:Fluorodeoxyglucose F18; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007205:Indium Radioisotopes; D007720:Knee Prosthesis / Q000009:adverse effects; D007962:Leukocytes / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D016459:Prosthesis-Related Infections / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D013671:Technetium Tc 99m Sulfur Colloid
chemical_list: D007205:Indium Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D013671:Technetium Tc 99m Sulfur Colloid