title: Quantitative Maximum Shear-Wave Stiffness of Breast Masses as a Predictor of Histopathologic Severity.
abstract: OBJECTIVE
  The objective of our study was to compare quantitative maximum breast mass stiffness on shear-wave elastography (SWE) with histopathologic outcome.
  
  
  METHODS
  From September 2008 through September 2010, at 16 centers in the United States and Europe, 1647 women with a sonographically visible breast mass consented to undergo quantitative SWE in this prospective protocol; 1562 masses in 1562 women had an acceptable reference standard. The quantitative maximum stiffness (termed "Emax") on three acquisitions was recorded for each mass with the range set from 0 (very soft) to 180 kPa (very stiff). The median Emax and interquartile ranges (IQRs) were determined as a function of histopathologic diagnosis and were compared using the Mann-Whitney U test. We considered the impact of mass size on maximum stiffness by performing the same comparisons for masses 9 mm or smaller and those larger than 9 mm in diameter.
  
  
  RESULTS
  The median patient age was 50 years (mean, 51.8 years; SD, 14.5 years; range, 21-94 years), and the median lesion diameter was 12 mm (mean, 14 mm; SD, 7.9 mm; range, 1-53 mm). The median Emax of the 1562 masses (32.1% malignant) was 71 kPa (mean, 90 kPa; SD, 65 kPa; IQR, 31-170 kPa). Of 502 malignancies, 23 (4.6%) ductal carcinoma in situ (DCIS) masses had a median Emax of 126 kPa (IQR, 71-180 kPa) and were less stiff than 468 invasive carcinomas (median Emax, 180 kPa [IQR, 138-180 kPa]; p = 0.002). Benign lesions were much softer than malignancies (median Emax, 43 kPa [IQR, 24-83 kPa] vs 180 kPa [IQR, 129-180 kPa]; p < 0.0001). Usual benign lesions were soft, including 62 cases of fibrocystic change (median Emax, 32 kPa; IQR, 24-94 kPa), 51 cases of fibrosis (median Emax, 36 kPa; IQR, 22-102 kPa), and 301 fibroadenomas (median Emax, 45 kPa; IQR, 30-79 kPa). Eight lipomas (median Emax, 14 kPa; IQR, 8-15 kPa), 154 cysts (median Emax, 29 kPa; IQR, 10-58 kPa), and seven lymph nodes (median Emax, 17 kPa; IQR, 9-40 kPa) were softer than usual benign lesions (p < 0.0001 for lipomas and cysts; p = 0.007 for lymph nodes). Risk lesions were slightly stiffer than usual benign lesions (p = 0.002) but tended to be softer than DCIS (p = 0.14). Fat necrosis and abscesses were relatively stiff. Conclusions were similar for both small and large masses.
  
  
  CONCLUSIONS
  Despite overlap in Emax values, maximum stiffness measured by SWE is a highly effective predictor of the histopathologic severity of sonographically depicted breast masses.
authors.affiliation: 1 Department of Radiology, Magee-Womens Hospital of UPMC, University of Pittsburgh School of Medicine, 300 Halket St, Pittsburgh, PA 15213.
authors.forename: Wendie A
authors.initials: WA
authors.lastname: Berg
authors.affiliation: 2 Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: Ellen B
authors.initials: EB
authors.lastname: Mendelson
authors.affiliation: 3 Imperial College, Hammersmith Campus, London, UK.
authors.forename: David O
authors.initials: DO
authors.lastname: Cosgrove
authors.affiliation: 4 Department of Statistics, Comprehensive Clinical Trials Unit, University College London, London, UK.
authors.forename: Caroline J
authors.initials: CJ
authors.lastname: Doré
authors.affiliation: 5 SuperSonic Imagine, Aix-en-Provence, France.
authors.forename: Joel
authors.initials: J
authors.lastname: Gay
authors.affiliation: 5 SuperSonic Imagine, Aix-en-Provence, France.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Henry
authors.affiliation: 5 SuperSonic Imagine, Aix-en-Provence, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Cohen-Bacrie
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D003937:Diagnosis, Differential; D054459:Elasticity Imaging Techniques; D005060:Europe; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009336:Necrosis; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012720:Severity of Illness Index; D016217:Ultrasonography, Mammary; D014481:United States
keywords: breast cancer; breast ultrasound; quantitative imaging; shear-wave elastography