Acute pulmonary embolism: effect of a computer-assisted detection prototype on diagnosis--an observer study.

PURPOSE: To assess the effect of a computer-assisted detection (CAD) prototype on observer performance for detection of acute pulmonary embolism (PE) with computed tomographic (CT) pulmonary angiography. MATERIALS AND METHODS: In this institutional review board-approved retrospective study, six observers with varying experience evaluated 158 PE-negative and 51 PE-positive CT pulmonary angiographic studies (mean age, 57 years; 111 women, 98 men) obtained consecutively during nights and weekends. Observers were asked to determine the presence of PE and to rank their diagnostic confidence without CAD and subsequently with CAD within a single reading session. Reading time was separately measured for both readings. Reader data were compared with an independent standard established by two readers, with a third in case of discordant results. Statistical evaluation was performed on a per-patient basis by using logistic regression for repeated measurements and Pearson correlation. RESULTS: With CAD, there was a significant increase in readers' sensitivity (P = .014) without loss of specificity (P = .853) on a per-patient basis. CAD assisted the readers in correcting an initial false-negative diagnosis in 15 cases, with the most proximal embolus at the segmental level in four cases and at the subsegmental level in 11 cases. In eight cases, readers accepted false-positive CAD candidate lesions on scans negative for PE, and in one case, a reader dismissed a true-positive finding. Reading time was extended by a mean of 22 seconds with the use of CAD. CONCLUSION: At the expense of increased reading time, CAD has the potential to increase reader sensitivity for detecting segmental and subsegmental PE without significant loss of specificity