Purpose: To assess the additional value of ultrasonography (US) to mammography in the diagnosis of malignant breast tumors.
Material and methods: Prospectively recorded final assessment categories for mammography and US were compared for 327 (228 palpable and 99 nonpalpable) consecutive malignant tumors confirmed at histology. The additional value of US was assessed for a subpopulation of 71 of these 327 malignancies after excluding mammographically conclusive malignant findings, ductal carcinomas in situ (DCIS), and invasive carcinomas presenting with suspicious microcalcifications, since there is no indication for performing US in these patients.
Results: A total of 267 (82%) of the 327 malignant tumors were correctly diagnosed on both imaging modalities. Mammography correctly diagnosed 41 cancers with false-negative US findings as compared with 11 true-positive US diagnoses of malignant tumors with false-negative findings on mammography (McNemar test p<0.001). US correctly diagnosed ("upgraded") 31 (10%) of the 327 malignant tumors with benign or indeterminate mammographic diagnoses. In the subpopulation, US upgraded 20 (42%) of 48 palpable and 10 (44%) of 23 nonpalpable malignant tumors.
Conclusion: The overall additional value of US to mammography in the diagnosis of breast cancer was rather limited in a population of mixed malignant tumors. Excluding cancers with mammographically conclusive diagnosis and suspicious microcalcifications as well as DCIS from analysis, US correctly upgraded more than 40% of palpable and nonpalpable malignant tumors.