title: Non-mass-like breast lesions at ultrasonography: feature analysis and BI-RADS assessment.
abstract: OBJECTIVE
  To analyze the features of non-mass-like (NML) breast lesions on ultrasound (US) and determine their corresponding malignancy rate and to stratify these lesion patterns according to US BI-RADS categories.
  
  
  METHODS
  One hundred sixty-four consecutive lesions were retrospectively classified into four types according to the US features, the corresponding positive predictive values (PPVs) were obtained. Clinical, imaging, and histopathological findings were reviewed.
  
  
  RESULTS
  Among the 164 lesions, 39 (24%) were classified as type Ia, 14 (8%) as type Ib, 39 (24%) as type IIa, 19 (12%) as type IIb, 19 (12%) as type III, and 34 (21%) as type IV. The PPVs for malignancy were 21% for type Ia, 79% for type Ib, 10% for type IIa, 58% for type IIb, 16% for type III, and 21% for type IV. All NML lesions were classified as BI-RADS category 4a (type IIa), 4b (type Ia, III and IV) and 4c (type Ib and IIb) according to their PPVs. There was a significantly higher frequency of malignancy among lesions of type Ib and type IIb compared with the other types (P<0.01 for each). Lesions with associated calcifications, presence of abnormal axillary nodes, or a mammographic finding of suspected malignancy had a higher probability of malignancy (P<0.05 for each).
  
  
  CONCLUSIONS
  US is useful in clarifying the indication for biopsy of NML lesions. The types of US classifications used in our study establish reliable references for the NML patterns when stratified according to the BI-RADS categories.
authors.affiliation: Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Kai-Hsiung
authors.initials: KH
authors.lastname: Ko
authors.affiliation: Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC. Electronic address: hsianhe@yahoo.com.tw.
authors.forename: Hsian-He
authors.initials: HH
authors.lastname: Hsu
authors.affiliation: Department of Surgery, Division of General Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Jyh-Cherng
authors.initials: JC
authors.lastname: Yu
authors.affiliation: Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Yi-Jen
authors.initials: YJ
authors.lastname: Peng
authors.affiliation: Department of Healthcare Administration, Asia University, Taichung, Taiwan, ROC.
authors.forename: Ho-Jui
authors.initials: HJ
authors.lastname: Tung
authors.affiliation: Section of Health Informatics, Institute of Public Health, National Defense Medical Center and University, Taipei, Taiwan, ROC.
authors.forename: Chi-Ming
authors.initials: CM
authors.lastname: Chu
authors.affiliation: Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Tsun-Hou
authors.initials: TH
authors.lastname: Chang
authors.affiliation: Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Wei-Chou
authors.initials: WC
authors.lastname: Chang
authors.affiliation: Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Wu
authors.affiliation: Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Yu-Pang
authors.initials: YP
authors.lastname: Lin
authors.affiliation: Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Giu-Cheng
authors.initials: GC
authors.lastname: Hsu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011237:Predictive Value of Tests; D011873:Radiology Information Systems / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D016217:Ultrasonography, Mammary / Q000379:methods*; D055815:Young Adult
keywords: BI-RADS; Breast carcinoma; Breast sonography; Breast ultrasound; Non-mass-like