Real-time digital contrast enhancement and magnification in the assessment of scaphoid and other wrist injuries.

A study on the value of a commercially available desk-top digital magnifier-contrast enhancer (DETECT System) was made in a series of 550 patients presenting with an acute wrist injury. Four radiologists, of varying experience, independently reviewed the radiographs on a conventional lightbox and later with the digitizer. In the scaphoid series (350 cases), the performance of the two more experienced radiologists was marginally better with the digitizer, whereas the less experienced radiologists performed slightly worse. Overall the digitizer improved the confidence of the radiologists in diagnosing correctly the presence of a scaphoid fracture but, for the less experienced radiologists, this was at the expense of identifying normality. In the wrist series (200 cases), the use of the digitizer resulted in a minor increase in the true positive and decrease in the false negative observations, but this was offset by a concomitant minor increase in the false positive and decrease in the true negative categories. Evaluation of the soft-tissue planes around the wrist joint showed a limited value in the identification of a scaphoid fracture with an overall positive predictive value of 0.26. Correlation of soft-tissue changes and the presence or absence of a scaphoid fracture was slightly worse with the digitizer. Possible causes for the apparently poorer performance of the digitizer are discussed, as well as the relative merits and potential value of the unit.