Medical imaging in trials has been used as a measure of efficacy for more than 20 years. While the clinical practice of radiology provides sufficient information for managing individual patients, this practice varies geographically within the United States and globally. It was recognized by FDA that variability in evaluating trial images at the sites necessitated a more standardized and controlled review process, which was described in the agency's 1994 "Points to Consider for Developing Medical Imaging Drug and Biologic Products."