Pre - Clinical ROC Studies of

| This paper reports the diagnostic performance of observers in detecting abnormalities in computer-generated mammogram-like images. A mathematical model of the human breast is deened in which breast tissues are simulated by spheres of diierent sizes and densities. Images are generated by casting rays from a speciied source, through the model, and onto an image plane. Observer performance when using two viewing modalities (stereo versus mono) is compared. In the stereo viewing mode, images are presented to the observer (wearing liquid-crystal display glasses), such that the left eye sees the left image only and the right eye sees the right image only. In this way, the images can be fused by the observer to obtain a sense of depth. In the mono viewing mode, identical images are presented to the left and right eyes so that no binocular disparities will be prodiced by the images. Observer response data are evaluated using receiver operating characteristic (ROC) analysis to characterize any diierence in detectability of abnormalities (in either the density or the arrangement of simulated tissue densities) using the two viewing modes. Our experimental results indicate the clear superiority of stereo viewing for detection of arrangement abnormalities. For detection of density abnormalities, the performance of the two viewing modes is similar. These preliminary results suggest that stereomammography may permit easier detection of certain tissue abnormalities, perhaps providing a route to earlier tumor detection in cases of breast cancer. Keywords| diagnostic radiology; digital mammography; receiver operating characteristic (ROC) analysis; stereo imaging.