Can prevalence expectations drive radiologists' behavior?

Rationale And Objectives: To measure the effect of explicit prevalence expectation on the performance of experienced radiologists during image interpretation of pulmonary lesions on chest radiographs.

Materials And Methods: Each of 22 experienced radiologists was allocated to one of three groups to interpret a set of 30 (15 abnormal) posteroanterior chest images on two occasions to decide if pulmonary lesions were present. Before each viewing, the radiologists were told that the images contained a specific number of abnormal images: group 1, 9 versus 15; group 2, 22 versus 15; and group 3, not told versus 15, respectively.