title: Reliability of X-rays and bone scans for the assessment of changes in skeletal metastases from breast cancer.
abstract: OBJECTIVE
  To examine the level of agreement among observers regarding changes between serial images of bone metastases.
  
  
  METHODS
  Thirty-five pairs of bone X-rays and 30 pairs of bone scans were selected from the files of patients with breast cancer involving the skeleton. All images in a pair were of the same site and had been taken at least 12 weeks apart. Thirteen radiologists and 14 nuclear medicine physicians examined the X-ray and bone scan pairs, respectively. Each assessed whether the changes between sequential films represented improvement, stability or worsening. Inter-observer agreement was analysed using the kappa statistic (kappa).
  
  
  RESULTS
  There was only fair overall agreement among radiologists regarding changes between X-rays (kappa = 0.23), but there was substantial agreement among nuclear medicine physicians for bone scan assessments (kappa = 0.62). Neither the experience of the observers nor the time between images had a significant effect on agreement. For X-rays, agreement was poorer if the response category was 'improvement' and if the type of bone lesion was mixed lytic/sclerotic.
  
  
  CONCLUSIONS
  Evaluation of serial X-rays is unreliable for determining the response of bone metastases. Scintigraphic evaluation has a higher internal validity for the determination of response, but it should not be used in isolation from other clinical data.
authors.affiliation: Walter and Eliza Hall Institute of Medical Research, St Vincent's Hospital, Melbourne, Victoria 3065, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Shackleton
authors.forename: K
authors.initials: K
authors.lastname: Yuen
authors.forename: A F
authors.initials: AF
authors.lastname: Little
authors.forename: S
authors.initials: S
authors.lastname: Schlicht
authors.forename: S-A
authors.initials: SA
authors.lastname: McLachlan
mesh_terms: D000368:Aged; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary*; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D015588:Observer Variation; D049268:Positron-Emission Tomography; D011859:Radiography / Q000379:methods; D015203:Reproducibility of Results; D014965:X-Rays