title: Shear-wave elastography improves the specificity of breast US: the BE1 multinational study of 939 masses.
abstract: OBJECTIVE
  To determine whether adding shear-wave (SW) elastographic features could improve accuracy of ultrasonographic (US) assessment of breast masses.
  
  
  METHODS
  From September 2008 to September 2010, 958 women consented to repeat standard breast US supplemented by quantitative SW elastographic examination in this prospective multicenter institutional review board-approved, HIPAA-compliant protocol. B-mode Breast Imaging Reporting and Data System (BI-RADS) features and assessments were recorded. SW elastographic evaluation (mean, maximum, and minimum elasticity of stiffest portion of mass and surrounding tissue; lesion-to-fat elasticity ratio; ratio of SW elastographic-to-B-mode lesion diameter or area; SW elastographic lesion shape and homogeneity) was performed. Qualitative color SW elastographic stiffness was assessed independently. Nine hundred thirty-nine masses were analyzable; 102 BI-RADS category 2 masses were assumed to be benign; reference standard was available for 837 category 3 or higher lesions. Considering BI-RADS category 4a or higher as test positive for malignancy, effect of SW elastographic features on area under the receiver operating characteristic curve (AUC), sensitivity, and specificity after reclassifying category 3 and 4a masses was determined.
  
  
  RESULTS
  Median participant age was 50 years; 289 of 939 (30.8%) masses were malignant (median mass size, 12 mm). B-mode BI-RADS AUC was 0.950; eight of 303 (2.6%) BI-RADS category 3 masses, 18 of 193 (9.3%) category 4a lesions, 41 of 97 (42%) category 4b lesions, 42 of 57 (74%) category 4c lesions, and 180 of 187 (96.3%) category 5 lesions were malignant. By using visual color stiffness to selectively upgrade category 3 and lack of stiffness to downgrade category 4a masses, specificity improved from 61.1% (397 of 650) to 78.5% (510 of 650) (P<.001); AUC increased to 0.962 (P=.005). Oval shape on SW elastographic images and quantitative maximum elasticity of 80 kPa (5.2 m/sec) or less improved specificity (69.4% [451 of 650] and 77.4% [503 of 650], P<.001 for both), without significant improvement in sensitivity or AUC.
  
  
  CONCLUSIONS
  Adding SW elastographic features to BI-RADS feature analysis improved specificity of breast US mass assessment without loss of sensitivity.
authors.affiliation: Magee-Womens Hospital, University of Pittsburgh School of Medicine, 300 Halket St, Pittsburgh, PA 15213, USA. wendieberg@gmail.com
authors.forename: Wendie A
authors.initials: WA
authors.lastname: Berg
authors.forename: David O
authors.initials: DO
authors.lastname: Cosgrove
authors.forename: Caroline J
authors.initials: CJ
authors.lastname: Doré
authors.forename: Fritz K W
authors.initials: FK
authors.lastname: Schäfer
authors.forename: William E
authors.initials: WE
authors.lastname: Svensson
authors.forename: Regina J
authors.initials: RJ
authors.lastname: Hooley
authors.forename: Ralf
authors.initials: R
authors.lastname: Ohlinger
authors.forename: Ellen B
authors.initials: EB
authors.lastname: Mendelson
authors.forename: Catherine
authors.initials: C
authors.lastname: Balu-Maestro
authors.forename: Martina
authors.initials: M
authors.lastname: Locatelli
authors.forename: Christophe
authors.initials: C
authors.lastname: Tourasse
authors.forename: Barbara C
authors.initials: BC
authors.lastname: Cavanaugh
authors.forename: Valérie
authors.initials: V
authors.lastname: Juhan
authors.forename: A Thomas
authors.initials: AT
authors.lastname: Stavros
authors.forename: Anne
authors.initials: A
authors.lastname: Tardivon
authors.forename: Joel
authors.initials: J
authors.lastname: Gay
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Henry
authors.forename: Claude
authors.initials: C
authors.lastname: Cohen-Bacrie
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005060:Europe; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D038622:Internationality; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D033081:Shear Strength; D016217:Ultrasonography, Mammary / Q000379:methods*; D014481:United States; D055815:Young Adult