title: Solid breast masses: classification with computer-aided analysis of continuous US images obtained with probe compression.
abstract: OBJECTIVE
  To prospectively evaluate the accuracy of continuous ultrasonographic (US) images obtained during probe compression and computer-aided analysis for classification of biopsy-proved (reference standard) benign and malignant breast tumors.
  
  
  METHODS
  This study was approved by the local ethics committee, and informed consent was obtained from all included patients. Serial US images of 100 solid breast masses (60 benign and 40 malignant tumors) were obtained with US probe compression in 86 patients (mean age, 45 years; range, 20-67 years). After segmentation of tumor contours with the level-set method, three features of strain on tissue from probe compression--contour difference, shift distance, area difference--and one feature of shape--solidity-were computed. A maximum margin classifier was used to classify the tumors by using these four features. The Student t test and receiver operating characteristic curve analysis were used for statistical analysis.
  
  
  RESULTS
  The mean values of contour difference, shift distance, area difference, and solidity were 3.52% +/- 2.12 (standard deviation), 2.62 +/- 1.31, 1.08% +/- 0.85, and 1.70 +/- 1.85 in malignant tumors and 9.72% +/- 4.54, 5.04 +/- 2.79, 3.17% +/- 2.86, and 0.53 +/- 0.63 in benign tumors, respectively. Differences with P < .001 were statistically significant for all four features. Area under the receiver operating characteristic curve (A(Z)) values for contour difference, shift distance, area difference, and solidity were 0.88, 0.85, 0.86, and 0.79, respectively. The A(Z) value of three features of strain was significantly higher than that of the feature of shape (P < .01). The accuracy, sensitivity, specificity, and positive and negative predictive values of US classifications that were based on values for these four features were 87.0% (87 of 100), 85% (34 of 40), 88% (53 of 60), 83% (34 of 41), and 90% (53 of 59), respectively, with an A(Z) value of 0.91.
  
  
  CONCLUSIONS
  Continuous US images obtained with probe compression and computer-aided analysis can aid in classification of benign and malignant breast tumors.
authors.affiliation: Department of Radiology and Clinical Research Institute, Seoul National University Hospital and the Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.
authors.forename: Woo Kyung
authors.initials: WK
authors.lastname: Moon
authors.forename: Ruey-Feng
authors.initials: RF
authors.lastname: Chang
authors.forename: Chii-Jen
authors.initials: CJ
authors.lastname: Chen
authors.forename: Dar-Ren
authors.initials: DR
authors.lastname: Chen
authors.forename: Wei-Liang
authors.initials: WL
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D001941:Breast Diseases / Q000145:classification* / Q000000981:diagnostic imaging*; D001943:Breast Neoplasms / Q000145:classification* / Q000000981:diagnostic imaging*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000379:methods