Photostimulable phosphor digital radiography of the extremities: diagnostic accuracy compared with conventional radiography

A direct comparison was made between digital and conventional radiographs to assess the relative accuracy of a photostimulable phosphor digital imaging system in detecting and localizing minor trauma in the extremities. Matched sets of images were obtained on 103 patients who came to the emergency department for radiographs of the hand, wrist, foot, or ankle. One set was obtained with a conventional screen/film system. The other set was obtained with photostimulable phosphor digital cassettes. The two sets of images of each patient were independently interpreted by three radiologists in a blinded fashion. The findings of each of these three readers were compared with the consensus opinion of two different radiologists. Receiver-operating-characteristic (ROC) curves were plotted for each of the three readers, areas under the curves were calculated, and true-positive fractions were determined at false-positive fractions of 0.1. Although no significant differences in the areas under the ROC curves for the two imaging systems were detected, conventional radiography showed a slight advantage. However, when true-positive fractions for fracture detection were compared at false-positive fractions of 0.1 a statistically significant difference was shown, with conventional screen/film radiography being more sensitive. This study raises questions about the use of currently available photostimulable phosphor systems for imaging trauma of the extremities and suggests that those systems should not be used exclusively.