Comparison of interpretations of CT angiograms in the evaluation of suspected pulmonary embolism by on-call radiology fellows and subsequently by radiology faculty.

Objective: Our objective was to evaluate interobserver variability in interpretations performed by on-call radiology fellows and subsequently by attending radiologists of CT angiograms obtained for clinically suspected pulmonary embolism and to evaluate factors contributing to discrepancies.

Materials And Methods: Written interpretations made by on-call fellows were compared with reports approved by attending radiologists for all CT angiograms obtained for suspected pulmonary embolism after work hours and on weekends in a recent 19-month period. Interpretations were stratified as positive, negative, or equivocal for pulmonary embolism. In cases of discordant interpretations, those CT angiograms were rereviewed by two thoracic radiologists; then patient medical records were reviewed for evidence of clinical effect. Technical and patient-related reasons for discordant interpretations of CT angiograms were recorded.

Results: Six hundred fifty-eight oncology patients were examined on CT angiography; five were examined twice. The fellows reported 137 CT angiograms (21%) as positive, 498 (75%) as negative, and 28 (4%) as equivocal for pulmonary embolism. Interpretations of the fellows and attending radiologists agreed in 93% (615/663) of CT angiograms (kappa = 0.80). The concordance rates for CT angiograms interpreted by fellows as positive (89%, 122/137), negative (96%, 479/498), and equivocal (50%, 14/28) were significantly different from each other (p < 0.001 for each). A significantly greater proportion of CT angiograms with discordant interpretations was reported to be technically limited (p < 0.01). No clear adverse clinical events were attributed to discordant interpretations of CT angiograms, although the death of one patient in that subgroup was of indeterminate cause.

Conclusion: In the evaluation of CT angiograms obtained for suspected pulmonary embolism, on-call fellows showed good agreement with attending radiologists. CT angiograms with discordant interpretations often were limited by technical or patient-related factors.