title: Comparison of positron emission tomography/CT and bremsstrahlung imaging following Y-90 radiation synovectomy.
abstract: BACKGROUND
  The aim of this study is to compare the results of positron emission tomography (PET)/CT with bremsstrahlung imaging following Y-90 radiation synovectomy.
  
  
  METHODS
  All patients referred to our institution for Y-90 radiation synovectomy between July 2011 and February 2012 underwent both PET/CT and bremsstrahlung planar (± single photon emission computed tomography (SPECT) or SPECT/CT) imaging at 4 or 24 h following administration of Y-90 silicate colloid. PET image acquisition was performed for between 15 and 20 min. In patients who underwent SPECT, side-by-side comparison with PET was performed and image quality/resolution scored using a five-point scale. The distribution pattern of Y-90 on PET and bremsstrahlung imaging was compared with the intra- or extra-articular location of Y-90 activity on fused PET/CT.
  
  
  RESULTS
  Thirteen joints (11 knees and two ankles) were imaged with both PET/CT and planar bremsstrahlung imaging with 12 joints also imaged with bremsstrahlung SPECT. Of the 12 joints imaged with SPECT, PET image quality/resolution was superior in 11 and inferior in one. PET demonstrated a concordant distribution pattern compared with bremsstrahlung imaging in all scans, with the pattern classified as diffuse in 12 and predominantly focal in one. In all 12 diffuse scans, PET/CT confirmed the Y-90 activity to be located intra-articularly. In the one predominantly focal scan, the fused PET/CT images localised the Y-90 activity to mostly lie in the extra-articular space of the knee.
  
  
  CONCLUSIONS
  PET/CT can provide superior image quality compared with bremsstrahlung imaging and may enable reliable detection of extra-articular Y-90 activity when there are focal patterns on planar bremsstrahlung imaging.
authors.affiliation: Department of Nuclear Medicine & PET Centre, The Alfred Hospital, Melbourne, Australia.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Barber
authors.forename: Kenneth S K
authors.initials: KS
authors.lastname: Yap
authors.forename: Martin H
authors.initials: MH
authors.lastname: Cherk
authors.forename: Anne
authors.initials: A
authors.lastname: Powell
authors.forename: Victor
authors.initials: V
authors.lastname: Kalff
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D064847:Multimodal Imaging / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013585:Synovitis / Q000175:diagnosis* / Q000532:radiotherapy*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D015021:Yttrium Radioisotopes / Q000627:therapeutic use*
chemical_list: D019275:Radiopharmaceuticals; D015021:Yttrium Radioisotopes
keywords: PET; PET/CT; bremsstrahlung; yttrium radiation synovectomy