title: Reassessment and Follow-Up Results of BI-RADS Category 3 Lesions Detected on Screening Breast Ultrasound.
abstract: OBJECTIVE
  The purpose of this study is to determine the frequency and the malignancy rate of BI-RADS category 3 lesions detected on screening breast ultrasound and to reassess whether they satisfied the requirements of the American College of Radiology Imaging Network (ACRIN) 6666 protocol.
  
  
  METHODS
  Of 28,796 asymptomatic women who underwent screening mammography during 2 years, 12,187 underwent additional ultrasound as part of the screening. Patients for whom BI-RADS category 3 lesions were seen on the ultrasound were selected. We reviewed the initial ultrasound showing BI-RADS category 3 lesions and mammograms. We also investigated the clinical outcome of these lesions using the reference standard of a combination of pathologic analysis and follow-up for at least 24 months.
  
  
  RESULTS
  The frequency of BI-RADS category 3 lesions detected on screening ultrasound was 14.6% (1783/12,187). Of the 1164 patients with a follow-up duration of at least 24 months or whose lesions were biopsied, eight were eventually proven to have malignancy (0.7%). The malignancy rate was 2.2% (4/184) for patients with abnormal mammograms and 0.4% (4/980) for those with normal mammograms. When the ACRIN 6666 protocols were strictly applied, 225 (19.3%) lesions were retrospectively recategorized as BI-RADS category 4 (n = 12) or category 2 (n = 213). All detected malignancies were early breast cancers with no lymph node metastasis.
  
  
  CONCLUSIONS
  Although the frequency of ultrasound BI-RADS category 3 lesions is considerably high (14.6%), the malignancy rate is very low (0.7%), especially in patients with a normal mammogram. Therefore, with BI-RADS category 3 assessment, careful evaluation is required to avoid unnecessary short-interval follow-up or biopsy.
authors.affiliation: 1 All authors: Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan, College of Medicine, 388-1 Pungnap-2-dong, Songpa-gu, Seoul 138-736, Korea.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Chae
authors.affiliation: 1 All authors: Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan, College of Medicine, 388-1 Pungnap-2-dong, Songpa-gu, Seoul 138-736, Korea.
authors.forename: Joo Hee
authors.initials: JH
authors.lastname: Cha
authors.affiliation: 1 All authors: Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan, College of Medicine, 388-1 Pungnap-2-dong, Songpa-gu, Seoul 138-736, Korea.
authors.forename: Hee Jung
authors.initials: HJ
authors.lastname: Shin
authors.affiliation: 1 All authors: Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan, College of Medicine, 388-1 Pungnap-2-dong, Songpa-gu, Seoul 138-736, Korea.
authors.forename: Woo Jung
authors.initials: WJ
authors.lastname: Choi
authors.affiliation: 1 All authors: Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan, College of Medicine, 388-1 Pungnap-2-dong, Songpa-gu, Seoul 138-736, Korea.
authors.forename: Hak Hee
authors.initials: HH
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000145:classification / Q000000981:diagnostic imaging*; D055088:Early Detection of Cancer; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D012189:Retrospective Studies; D012720:Severity of Illness Index; D016217:Ultrasonography, Mammary; D055815:Young Adult
keywords: BI-RADS; breast neoplasm; probably benign lesion; ultrasound