Assessing the value of diagnostic imaging: the role of perception

The value of diagnostic radiology rests in its ability to provide information. Information is defined as a reduction in randomness. Quality improvement in any system requires diminution in the variation in its performance. The major variation in performance of the system of diagnostic radiology occurs in observer performance and in the communication of information from the observer to someone who will apply that information to the benefit of the patient. The ability to provide information can be determined by observer performance studies using a receiver-operating characteristic (ROC) curve analysis. The amount of information provided by each observer can be measured in terms of the uncertainty they reduce. Using a set of standardized radiographs, some normal and some abnormal, sorting them randomly, and then asking an observer to redistribute them according to their probability of normality can measure the difference in the value added by different observers. By applying this observer performance measure, we have been able to characterize individual radiologists, groups of radiologists, and regions of the United States in their ability to add value in chest radiology. The use of these technologies in health care may improve upon the contribution of diagnostic imaging.