Reliability of X-rays and bone scans for the assessment of changes in skeletal metastases from breast cancer.
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.
Shackleton
M
M
Walter and Eliza Hall Institute of Medical Research, St Vincent's Hospital, Melbourne, Victoria 3065, Australia.
Yuen
K
K
Little
A F
AF
Schlicht
S
S
McLachlan
S-A
SA
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