Ovarian cancer: comparison of observer performance for four methods of interpreting CT scans

To assess the effects of four interpretative methods on observers' mean sensitivity and specificity by using computed tomography (CT) of ovarian carcinoma as a model.

CT scans in 98 patients with ovarian carcinoma and 49 women who were disease free were retrospectively reviewed by four experienced blinded radiologists to compare single-observer reading, single-observer reading with an anatomic checklist, paired-observer reading (simultaneous double reading), and replicated reading (combination of two independent readings). Confidence level scoring was used to identify three possible disease forms in each patient: extranodal tumor, lymphadenopathy, and ascites. Patient conditions were then categorized as abnormal or normal.

There were no significant improvements in sensitivity or specificity for classification of patient conditions as abnormal or normal when comparing single-observer interpretation with single-observer interpretation with a checklist or paired-observer interpretation. Although there was no significant improvement in the mean sensitivity (93% vs 94%) by using the replicated reading method, there was a statistically significant improvement in mean specificity (85% vs 79%) for the replicated readings compared with single-observer interpretations (P < .05).

Diagnostic aids such as checklists and paired simultaneous readings did not lead to an improved mean observer performance for experienced readers. However, an increase in the mean specificity occurred with replicated readings.