title: A preliminary prospective study to compare the diagnostic performance of assist strain ratio versus manual strain ratio.
abstract: OBJECTIVE
  The objectives of this study were to demonstrate the non-inferiority of assist strain ratio (ASR)-a newly developed application tool-to manual strain ratio (MSR)-a currently available standard diagnostic tool-and to calculate the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of MSR and ASR.
  
  
  METHODS
  Ninety-eight mass lesions in the mammary gland (30 malignant and 68 benign) were included in the study. Skilled physicians performed the elastography scanning by applying minimal vibration. MSRs were obtained and compared with ASRs calculated from the same elastography image to test the correlation between the two groups of data.
  
  
  RESULTS
  Diagnostic performance of MSR at a cut-off of 5.0 showed a sensitivity of 84.4 %, a specificity of 80.4 %, an accuracy of 81.6 %, a PPV of 65.5 %, and an NPV of 92.1 %. Diagnostic performance of ASR at a cut-off of 5.0 showed a sensitivity of 74.4 %, a specificity of 84.3 %, an accuracy of 81.3 %, a PPV of 67.7 %, and an NPV of 88.2 %. The areas under the curve (AUCs) for MSR and ASR were found to be 0.885 and 0.875, respectively.
  
  
  CONCLUSIONS
  ASR demonstrated excellent diagnostic potential and was highly correlated with MSR performed by skilled physicians (r = 0.69, p < 0.05).
authors.affiliation: Department of Senology, Tsukuba Medical Center Foundation, Tsukuba, Ibaraki, Japan. e-ueno@tmch.or.jp.
authors.forename: Ei
authors.initials: E
authors.lastname: Ueno
authors.affiliation: Total Health Evaluation Center Tsukuba, Tsukuba Medical Center Foundation, Tsukuba, Ibaraki, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Tohno
authors.affiliation: Department of Senology, Tsukuba Medical Center Foundation, Tsukuba, Ibaraki, Japan.
authors.forename: Isamu
authors.initials: I
authors.lastname: Morishima
authors.affiliation: Department of Senology, Tsukuba Medical Center Foundation, Tsukuba, Ibaraki, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Umemoto
authors.affiliation: Medical Systems Engineering Division 2, Hitachi Aloka Medical, Ltd., Kokubunji, Tokyo, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Waki
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D011446:Prospective Studies; D015203:Reproducibility of Results; D016217:Ultrasonography, Mammary / Q000379:methods*
keywords: Assist strain ratio; Breast cancer; Elastography; FLR; Strain ratio