Breast ultrasound diagnostic performance and outcomes for mass lesions using Breast Imaging Reporting and Data System category 0 mammogram

PURPOSE To evaluate the outcomes and diagnostic performance of ultrasonography after a Breast Imaging Reporting and Data System (Bi-RADS) category 0 mammogram. MATERIAL AND METHODS This retrospective study reviewed 4,384 consecutive patients who underwent a screening mammography from January 2005 to July 2006; 391 of the 4,384 exams were classified as Bi-RADS category 0. After exclusions, 241 patients received subsequent sonogram. Ultrasonography was considered diagnostic when the Bi-RADS category was changed to 2, 4, or 5, and it was considered indeterminate (Bi-RADS 3) when the results indicated that the patients should return for a mammographic follow-up. The outcomes of these patients were assessed to evaluate the diagnostic performance of ultrasonography. RESULTS The mean age of the patients was 53.3 years (ranging from 35 to 81). Of the 241 patients, ultrasonography was considered diagnostic in 146 (60.6%) patients and indeterminate in 95 (39.4%) patients. In the diagnostic group, 111 out of 146 patients (70.2%) had a sonogram result of Bi-RADS category 2 after a 2-year follow-up without evidence of malignancy. Furthermore, 35 out of 146 patients (29.8%) had a suspicious sonogram with a result of Bi-RADS category 4. After a tissue sampling procedure, 10 patients were confirmed to have breast cancer, and 25 had benign histopathological features without any evidence of malignancy after a 2-year follow-up. The sensitivity of ultrasonography was 100%, specificity was 89.1%, and overall accuracy was 89.6%. CONCLUSIONS Based on the degree of resolution and its diagnostic performance, ultrasonography was determined to be an excellent method for the subsequent evaluation of Bi-RADS 0 mammograms.