The reliability of the 3-phase bone scan in suspected scaphoid fracture: an inter- and intraobserver variability analysis.

In the diagnosis of scaphoid fracture, the dynamic phase of the radionuclide bone scan alone has been recommended as an early test. To evaluate the independent reliability of the dynamic and static phases of the 3-phase bone scan in this diagnosis, 3 examiners reviewed the 3-phase bone scans of a series of 60 patients with clinical signs of fracture of the carpal scaphoid and with negative or non-diagnostic initial radiographs. The interpretation was performed independently and without the benefit of additional data. The bone scans were reviewed after 1 year by the same observers. The results were analyzed using kappa statistics. The bone scan was suspicious of fracture of the scaphoid in 15 patients. Irrespective of training and experience, the kappa values of the dynamic bone scan between any 2 observers did not exceed 0.57. The kappa values increased significantly when the static phase of the bone scan was examined (> 0.81). The intraobserver variability showed a similar pattern. We conclude that in suspected scaphoid fracture, the dynamic phase of the radionuclide bone scan alone cannot be used as a reliable diagnostic approach because of the low inter- and intraobserver agreement in the interpretation, irrespective of the experience and training of the observer.