title: Bone and Gallium Single-Photon Emission Computed Tomography-Computed Tomography is Equivalent to Magnetic Resonance Imaging in the Diagnosis of Infectious Spondylodiscitis: A Retrospective Study.
abstract: OBJECTIVE
  Spondylodiscitis has historically been a difficult clinical diagnosis. Two imaging techniques that address this problem are magnetic resonance imaging (MRI) and combined bone (99mTc-methylene diphosphonate) and gallium-67 single-photon emission computed tomography-computed tomography (SPECT-CT). Their accuracies have not been adequately compared. The purpose of this study is to compare the sensitivities and specificities of bone and gallium SPECT-CT and MRI in infectious spondylodiscitis.
  
  
  METHODS
  This retrospective study assessed all patients who underwent a bone or gallium SPECT-CT of the spine to assess for infectious spondylodiscitis from January 1, 2010, to May 2, 2012, at a single tertiary care centre. Thirty-four patients (23 men; average 62 ± 14 years of age) were included. The results of the bone or gallium SPECT-CT were compared against MRI for all patients in the cohort who underwent an MRI within 12 weeks of the SPECT-CT. A diagnosis of spondylodiscitis in the discharge summary was considered the reference standard, and was based on a combination of clinical scenario, response to therapy, imaging, or microbiology.
  
  
  RESULTS
  Spondylodiscitis was diagnosed in 18 patients and excluded in 16. Bone or gallium SPECT-CT and MRI had similar (P > .05; κ = 0.74) sensitivities (0.94 vs 0.94), specificities (1.00 vs 1.00), positive predictive values (1.00 vs 1.00), negative predictive values (0.94 vs 0.80), and accuracies (0.97 vs 0.95) when compared to the reference standard.
  
  
  CONCLUSIONS
  Although MRI remains the initial modality of choice in diagnosing spondylodiscitis, bone and gallium SPECT-CT appears diagnostically equivalent and should be considered a viable supplementary or alternative imaging modality particularly if there is contraindication or inaccessibility to MRI.
authors: Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton, Alberta, Canada. Electronic address: astamm@ualberta.ca.
authors: Alexander S
authors: AS
authors: Tamm
authors: Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton, Alberta, Canada.
authors: Jonathan T
authors: JT
authors: Abele
mesh_terms: D015299:Discitis / Q000000981:diagnostic imaging*; D005260:Female; D005710:Gallium Radioisotopes; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013669:Technetium Tc 99m Medronate; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D005710:Gallium Radioisotopes; D019275:Radiopharmaceuticals; D013669:Technetium Tc 99m Medronate
keywords: Bone scan; Gallium scan; Infectious spondylodiscitis; Magnetic resonance imaging; Single-photon emission computed tomography