Film-screen versus digitized mammography: Assessment of clinical equivalence

OBJECTIVE, The purpose of this study was to determine whether diagnostic ac curacy and callback rates using digitized film images are equivalent to tho se using film-screen mammograms. MATERIALS AND METHODS. Sixty sets of mammograms (four views per case) were digitized at a spatial resolution of 100 mu m. The images were reviewed by seven mammographers. Five regions were evaluated in each breast. Each regio n was scored on a scale of 0-100% for suspicion of malignancy and a, receiv er operating characteristic analysis was performed. Callback rates were cal culated using a published lexicon scale. RESULTS. The observers' mean diagnostic accuracies using films and digitize d images were 0.872 and 0.848, respectively. The upper 95% confidence bound ary on the difference in accuracy was 0.066. The mean callback rate for nor mal, benign, and malignant areas using films versus digitized images was 0. 048 versus 0.055, 0.498 versus 0.441, and 0.786 versus 0.737, respectively. The upper 95% confidence boundary for the absolute difference in callback rates was 0.037, 0.026, and 0.130 for normal, benign, and malignant areas, respectively. CONCLUSION. The diagnostic accuracies of the digitized images and films wer e similar; however, an increase in callback rates of 0.037 (i.e., upper 95% confidence boundary) for normal results and a reduction in the callback ra tes of 0.130 for malignant lesions is important. The use of digitized film images, at a spatial resolution of 100 mu m, may compromise patient treatme nt in clinical practice.