title: Correlation of clinical outcomes with bremsstrahlung and Y-90 PET/CT imaging findings following Y-90 radiosynoviorthesis: a prospective study.
abstract: BACKGROUND
  It is unclear how to predict which patients will respond to Y-90 radiosynoviorthesis. The aim of this study is to correlate clinical outcomes following Y-90 radiosynoviorthesis with bremsstrahlung and Y-90 PET/CT imaging findings.
  
  
  METHODS
  Fifty-one joints underwent bremsstrahlung planar and Y-90 PET/CT imaging following Y-90 radiosynoviorthesis. The Y-90 distribution pattern on bremsstrahlung planar imaging was classified as diffuse or non-diffuse and compared with the intra or extra-articular location of activity on Y-90 PET/CT. Treatment response was assessed by patients and clinicians at 6 months. In patients who underwent bremsstrahlung SPECT, side-by-side comparison with PET was performed with image quality/resolution scored using a five-point-scale.
  
  
  RESULTS
  Bremsstrahlung planar images were classified as diffuse in 33/51 (65 %) and non-diffuse in 18/51 (35 %) scans. There was no association between treatment response and the bremsstrahlung planar imaging pattern. PET/CT confirmed an intra-articular location in all 33/33 (100 %) diffuse scans and an extra-articular location in 3/18 (17 %) non-diffuse scans. Of the three joints with extra-articular activity, none had any treatment response. Excluding these three joints, there remained no association between the bremsstrahlung planar imaging pattern and treatment response. Of the 42 joints imaged with SPECT, PET image quality/resolution was classified as superior in 40 (95 %). In one patient with extra-articular activity on PET/CT, SPECT/CT was unable to definitively localise the activity to the intra or extra-articular space.
  
  
  CONCLUSIONS
  The distribution pattern on bremsstrahlung planar imaging did not correlate with clinical outcome following Y-90 radiosynoviorthesis in our study population. However, in patients with non-diffuse planar imaging patterns, Y-90 PET/CT should be considered to exclude extra-articular activity with PET providing superior image quality compared to SPECT.
authors.affiliation: Department of Nuclear Medicine & PET, The Alfred Hospital, Melbourne, 3004, Australia. T.Barber@alfred.org.au.|Department of Medicine, Monash University, Alfred Hospital Campus, Melbourne, 3004, Australia. T.Barber@alfred.org.au.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Barber
authors.affiliation: Department of Nuclear Medicine & PET, The Alfred Hospital, Melbourne, 3004, Australia.|Department of Medicine, Monash University, Alfred Hospital Campus, Melbourne, 3004, Australia.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Cherk
authors.affiliation: Department of Medicine, Monash University, Alfred Hospital Campus, Melbourne, 3004, Australia.|Department of Rheumatology, The Alfred Hospital, Melbourne, 3004, Australia.
authors.forename: Anne
authors.initials: A
authors.lastname: Powell
authors.affiliation: Department of Nuclear Medicine & PET, The Alfred Hospital, Melbourne, 3004, Australia.
authors.forename: Kenneth S K
authors.initials: KS
authors.lastname: Yap
authors.affiliation: Department of Epidemiology and Preventive Medicine, Monash University, Alfred Hospital Campus, Melbourne, 3004, Australia.
authors.forename: Baki
authors.initials: B
authors.lastname: Billah
authors.affiliation: Department of Nuclear Medicine & PET, The Alfred Hospital, Melbourne, 3004, Australia.|Department of Medicine, Monash University, Alfred Hospital Campus, Melbourne, 3004, Australia.
authors.forename: Victor
authors.initials: V
authors.lastname: Kalff
keywords: Bremsstrahlung; PET/CT; Radiation synovectomy; Radiosynoviorthesis; SPECT/CT; Yttrium