SEQUENTIAL VIEWING OF ABDOMINAL CT IMAGES AT VARYING RATES

PURPOSE: To evaluate radiologists' ability to detect abdominal masses during sequential viewing of series of computed tomographic (CT) scans at varying rates. MATERIAL AND METHODS: Receiver operating characteri stic (ROC) analysis was used to assess the ability of five experienced radiologists to determine the presence or absence of subtle abdominal masses in 29 cases (15 positive, 14 negative) while viewing CT scans sequentially at different rates (0.5, 1, 2, 4, 7, and 21 images per se cond) and also at reader-selectable rates. RESULTS: Even at extremely fast viewing rates (21 images per second), radiologists performed sign ificantly better (P < .05) than would be expected by chance alone (ave rage area A(z) under the ROC curve = 0.73 vs 0.5). As the viewing rate decreased, their performance increased. The reader-selectable mode wa s better than any fixed-rate cine mode (average A(z) = 0.93). CONCLUSI ON. Fixed-rate sequential viewing of CT images for the primary diagnos is of subtle abdominal masses should be restricted to no more than one or two images per second, but the reader-selectable viewing mode is p referable to any fixed-rate cine mode.