Intra- and interobserver agreement in the interpretation of navicular bones on radiographs and computed tomography scans.
BACKGROUND
Criteria for the radiographic evaluation of navicular bones in horses have been published to standardise classification of radiographic signs. However, intra- and interobserver agreement have not been established.


OBJECTIVE
To determine intra- and interobserver agreement in the evaluation of radiographic and computed tomographic (CT) navicular changes. It was hypothesised that: 1) intraobserver agreement would be better than interobserver agreement; 2) agreement would be better for CT than for radiography; and 3) pathological changes would be recognised with greater certainty with CT.


METHODS
Radiographs and CT scans of 60 cadaver navicular bones were evaluated by 3 observers using published criteria. A subset of 30 studies was evaluated twice by one observer. Agreement was tested using the kappa statistic. Certainty about pathological changes was evaluated by giving the observers the option to choose 'not sure'.


RESULTS
Agreement varied from poor to almost perfect for radiographic evaluation and from poor to substantial for CT evaluation. For radiographic evaluation mean interobserver agreement was fair, as it was for CT evaluation. For radiographic evaluation mean intraobserver agreement was moderate as it was for CT evaluation. Pathological changes were evaluated with greater certainty on CT scans compared to radiographs; however, this was not associated with improved agreement.


CONCLUSIONS
Variations in classification of navicular lesions in radiographic and CT studies were considerable between and within observers and challenge the use of such studies for diagnostic and prognostic purposes.


CONCLUSIONS
The results of this study allowed the identification of evaluation criteria with sufficient precision to be useful for navicular bone evaluation.
Department of Veterinary Clinical Sciences, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire AL9 7TA, UK.
A M
AM
Groth
S A
SA
May
M P
MP
Weaver
R
R
Weller
D000818:Animals; D002102:Cadaver; D003937:Diagnosis, Differential; D006734:Horse Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D006736:Horses; D006801:Humans; D015588:Observer Variation; D011379:Prognosis; D011859:Radiography / Q000379:methods / Q000592:standards / Q000662:veterinary*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013639:Tarsal Bones / Q000000981:diagnostic imaging* / Q000473:pathology; D013643:Tarsus, Animal / Q000000981:diagnostic imaging* / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000592:standards / Q000662:veterinary*