title: Usefulness of adding SPECT/CT to 99mTc-hexamethylpropylene amine oxime (HMPAO)-labeled leukocyte imaging for diagnosing prosthetic joint infections.
abstract: OBJECTIVE
  This study evaluated the usefulness of adding single-photon emission computed tomography (SPECT)/computed tomography (CT) (SPECT/CT) to technetium Tc 99m (Tc) hexamethylpropylene amine oxime (HMPAO)-labeled leukocyte imaging for diagnosing infections in hip or knee joint prostheses.
  
  
  METHODS
  The Tc-HMPAO-labeled leukocyte scans of 164 patients (71 with hip prostheses and 93 with knee prostheses) with clinically suspected prosthetic infections were reviewed retrospectively. Planar images were taken 4 to 6 and 21 to 26 hours after injecting the labeled leukocytes and SPECT/CT images were obtained 4 to 6 hours after the injection. The final diagnosis of infection was based on pathologic findings (n = 70), bacteriological data (n = 61), or clinical follow-up (n = 33).
  
  
  RESULTS
  Of the 164 patients, 89 patients had a diagnosis of prosthetic joint infections. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of the planar images alone were 82.0%, 88.0%, 89.0%, 80.5%, and 84.8%, respectively. When the planar images were combined with SPECT, the sensitivity, specificity, PPV, NPV, and diagnostic accuracy were 91.0%, 88.0%, 90.0%, 89.2%, and 89.6%, respectively. When the planar images were combined with SPECT/CT, these values increased further to 93.3%, 93.3%, 94.3%, 92.1%, and 93.3%, respectively. Adding CT to SPECT resulted in a greater increase in sensitivity and specificity for hip prosthesis infections than for knee prosthesis infections. SPECT/CT mainly contributed by precisely localizing the anatomical site of the active inflammatory lesion and by delineating the extent of the lesion after diagnosis with SPECT.
  
  
  CONCLUSIONS
  Single-photon emission computed tomography/CT combined with Tc-HMPAO-labeled leukocyte imaging was useful for diagnosing prosthesis infections, particularly in hip prosthesis infections, as it improved diagnostic accuracy and provided anatomical localization data.
authors.affiliation: From the *Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea; †Department of Radiology, Uijeongbu St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea; ‡Department of Orthopedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Hye Ok
authors.initials: HO
authors.lastname: Kim
authors.forename: Sae Jung
authors.initials: SJ
authors.lastname: Na
authors.forename: Seung Jun
authors.initials: SJ
authors.lastname: Oh
authors.forename: Bong Sung
authors.initials: BS
authors.lastname: Jung
authors.forename: Soo-Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Jae Suk
authors.initials: JS
authors.lastname: Chang
authors.forename: Seong-Il
authors.initials: SI
authors.lastname: Bin
authors.forename: Jin-Sook
authors.initials: JS
authors.lastname: Ryu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D007720:Knee Prosthesis; D007962:Leukocytes / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D011237:Predictive Value of Tests; D016459:Prosthesis-Related Infections / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed
chemical_list: D019690:Technetium Tc 99m Exametazime