Diagnostic performance of screening breast ultrasonography in women with mammographically dense breast : application of the downgrade criteria

Abstract

Purpose: To investigate whether the application of the downgrade criteria on supplemental screening US for women with negative mammography but dense breasts can reduce Breast Imaging Reporting and Data System (BI-RADS) category 3-4a without a loss of cancer detection. Methods: This retrospective study included 4730 women with negative mammography but dense breast who underwent radiologist-performed, hand-held screening US from March 2009 to February 2013. To reduce BI-RADS category 3-4a on screening US, since March 2010, complicated cysts 5mm or smaller and circumscribed oval-shaped solid masses 5mm or smaller were downgraded to BI-RADS category 2. The distribution of BI-RADS category, cancer detection yield and diagnostic performances of screening US were analyzed and compared before (year 2009: from March 2009 to February 2010) and after (year 2010-2012: from March 2010 to February 2013) the application of the downgrade criteria, with the reference standard defined as a combination of pathology and 12-month follow-up. Performances between less-experienced (19 fellows with 1-2 years of experience) and experienced (3 staffs with 12-18 years of experience) radiologists were compared. Results: The application of downgrade criteria reduced BI-RADS category 3-4a in both less-experienced and experienced radiologists. Screening US detected 12 cancers (three ductal carcinoma in situs and nine invasive cancers) during four years. There were no differences in cancer detection yields before and after the application of downgrade criteria. Interval cancers were not detected. Specificity, accuracy and the area under the receiver operating characteristic curve significantly increased after the application of downgrade criteria. Conclusion: The application of downgrade criteria reduced BI-RADS category 3-4a without a loss of cancer detection.