title: A new computer aided diagnosis system for evaluation of chronic liver disease with ultrasound shear wave elastography imaging.
abstract: OBJECTIVE
  Classify chronic liver disease (CLD) from ultrasound shear-wave elastography (SWE) imaging by means of a computer aided diagnosis (CAD) system.
  
  
  METHODS
  The proposed algorithm employs an inverse mapping technique (red-green-blue to stiffness) to quantify 85 SWE images (54 healthy and 31 with CLD). Texture analysis is then applied involving the automatic calculation of 330 first and second order textural features from every transformed stiffness value map to determine functional features that characterize liver elasticity and describe liver condition for all available stages. Consequently, a stepwise regression analysis feature selection procedure is utilized toward a reduced feature subset that is fed into the support vector machines (SVMs) classification algorithm in the design of the CAD system.
  
  
  RESULTS
  With regard to the mapping procedure accuracy, the stiffness map values had an average difference of 0.01 ± 0.001 kPa compared to the quantification results derived from the color-box provided by the built-in software of the ultrasound system. Highest classification accuracy from the SVM model was 87.0% with sensitivity and specificity values of 83.3% and 89.1%, respectively. Receiver operating characteristic curves analysis gave an area under the curve value of 0.85 with [0.77-0.89] confidence interval.
  
  
  CONCLUSIONS
  The proposed CAD system employing color to stiffness mapping and classification algorithms offered superior results, comparing the already published clinical studies. It could prove to be of value to physicians improving the diagnostic accuracy of CLD and can be employed as a second opinion tool for avoiding unnecessary invasive procedures.
authors.affiliation: Department of Medical Physics, School of Medicine, University of Patras, Rion GR 26504, Greece.
authors.forename: Ilias
authors.initials: I
authors.lastname: Gatos
authors.affiliation: Department of Medical Physics, School of Medicine, University of Patras, Rion GR 26504, Greece.
authors.forename: Stavros
authors.initials: S
authors.lastname: Tsantis
authors.affiliation: Department of Radiology, School of Medicine, University of Athens, Athens GR 12461, Greece.
authors.forename: Stavros
authors.initials: S
authors.lastname: Spiliopoulos
authors.affiliation: Department of Radiology, School of Medicine, University of Patras, Patras GR 26504, Greece.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Karnabatidis
authors.affiliation: Diagnostic Echotomography SA, 317C Kifissias Avenue, Kifissia GR 14561, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Theotokas
authors.affiliation: Diagnostic Echotomography SA, 317C Kifissias Avenue, Kifissia GR 14561, Greece.
authors.forename: Pavlos
authors.initials: P
authors.lastname: Zoumpoulis
authors.affiliation: SuperSonic Imagine SA, Aix-en-Provence FR 13857, France.
authors.forename: Thanasis
authors.initials: T
authors.lastname: Loupas
authors.affiliation: Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030.
authors.forename: John D
authors.initials: JD
authors.lastname: Hazle
authors.affiliation: Department of Medical Physics, School of Medicine, University of Patras, Rion GR 26504, Greece and Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030.
authors.forename: George C
authors.initials: GC
authors.lastname: Kagadis
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002908:Chronic Disease; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008107:Liver Diseases / Q000000981:diagnostic imaging*; D008297:Male; D055595:Mechanical Phenomena; D008875:Middle Aged; D055815:Young Adult