title: Qualitative pattern classification of shear wave elastography for breast masses: how it correlates to quantitative measurements.
abstract: OBJECTIVE
  To determine the correlation of qualitative shear wave elastography (SWE) pattern classification to quantitative SWE measurements and whether it is representative of quantitative SWE values with similar performances.
  
  
  METHODS
  From October 2012 to January 2013, 267 breast masses of 236 women (mean age: 45.12 ± 10.54 years, range: 21-88 years) who had undergone ultrasonography (US), SWE, and subsequent biopsy were included. US BI-RADS final assessment and qualitative and quantitative SWE measurements were recorded. Correlation between pattern classification and mean elasticity, maximum elasticity, elasticity ratio and standard deviation were evaluated. Diagnostic performances of grayscale US, SWE parameters, and US combined to SWE values were calculated and compared.
  
  
  RESULTS
  Of the 267 breast masses, 208 (77.9%) were benign and 59 (22.1%) were malignant. Pattern classifications significantly correlated with all quantitative SWE measurements, showing highest correlation with maximum elasticity, r = 0.721 (P<0.001). Sensitivity was significantly decreased in US combined to SWE measurements to grayscale US: 69.5-89.8% to 100.0%, while specificity was significantly improved: 62.5-81.7% to 13.9% (P<0.001). Area under the ROC curve (Az) did not show significant differences between grayscale US to US combined to SWE (P>0.05).
  
  
  CONCLUSIONS
  Pattern classification shows high correlation to maximum stiffness and may be representative of quantitative SWE values. When combined to grayscale US, SWE improves specificity of US.
authors.affiliation: Department of Radiology, CHA Bundang Medical Center, CHA University, School of Medicine, South Korea; Department of Radiology, Research Institute of Radiological Science, Yonsei University, College of Medicine, South Korea. Electronic address: lvjenny0417@gmail.com.
authors.forename: Jung Hyun
authors.initials: JH
authors.lastname: Yoon
authors.forename: Kyung Hee
authors.initials: KH
authors.lastname: Ko
authors.forename: Hae Kyoung
authors.initials: HK
authors.lastname: Jung
authors.forename: Jong Tae
authors.initials: JT
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008875:Middle Aged; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016217:Ultrasonography, Mammary / Q000379:methods*; D055815:Young Adult
keywords: Biopsy; Breast; Elastography; Shear wave; Ultrasound