Interobserver agreement in sonographic diagnosis of breast tumors

Abstract

Objective: To evaluate interobserver agreement in the interpretation of breast ultrasonography. Methods: 55 breast masses (30 benign, 24 malignant) were interpreted by seven radiologists using a CRT viewing station. US criteria for differentiating between benign and malignant lesions included shape, border, boundary echoes, internal echoes, posterior echoes, and bilateral shadows. Each criterion and the observers' final impression was scored using the 5-point rating scales. For analyzing interobserver agreement, the kappa ( κ) values were employed. Results: The κ values of shape and posterior echoes were significantly higher than those of the other four criteria ( P<0.05). Agreement was intermediate in border and internal echoes, and was low in boundary echoes and bilateral shadows. Agreement in the senior group (four observers) was relatively higher than that in the junior group (three observers) for all criteria but for internal echoes. Easily-diagnosed cases showed significantly higher κ values compared with more ambiguous cases ( P<0.05). Conclusion: Interobserver agreement in shape and posterior echoes was significantly higher than those of the other four criteria. Agreement was significantly dependent on case difficulty.