title: MR elastography of liver tumours: value of viscoelastic properties for tumour characterisation.
abstract: OBJECTIVE
  To assess the value of the viscoelastic parameters in the characterisation of liver tumours at MR elastography.
  
  
  METHODS
  Ninety-four patients with liver tumours >1 cm prospectively underwent MR elastography using 50-Hz mechanical waves and a full three-directional motion-sensitive sequence. The model-free viscoelastic parameters (the complex shear modulus and its real and imaginary parts, i.e. the storage and loss moduli) were calculated in 72 lesions after exclusion of cystic, treated or histopathologically undetermined tumours.
  
  
  RESULTS
  We observed higher absolute shear modulus and loss modulus in malignant versus benign tumours (3.38 ± 0.26 versus 2.41 ± 0.15 kPa, P < 0.01 and 2.25 ± 0.26 versus 1.05 ± 0.13 kPa, P < 0.001, respectively). Moreover, the loss modulus of hepatocellular carcinomas was significantly higher than in benign hepatocellular tumours. The storage modulus did not differ significantly between malignant and benign tumours. The area under the receiver-operating characteristic curve of loss modulus was significantly larger than that of the absolute shear modulus and storage modulus when comparing malignant and benign lesions.
  
  
  CONCLUSIONS
  The increased loss modulus is a better discriminator between benign and malignant tumours than the increased storage modulus or absolute value of the shear modulus.
  
  
  CONCLUSIONS
  • Magnetic Resonance elastography is a new method of assessing the liver.                                                  • Increased loss modulus is an indicator of malignancy in hepatic tumours.                                                  • Loss modulus is a better discriminator than absolute shear modulus values.                                                  • The viscoelastic properties of lesions offer promise for characterising liver tumours.
authors.affiliation: Department of Radiology, University Paris Diderot, Sorbonne Paris Cité, INSERM UMR 773, University Hospitals Paris Nord Val de Seine, Beaujon, 100 boulevard du Général Leclerc, 92118, Clichy Cedex, France. philippe.garteiser@inserm.fr
authors.forename: Philippe
authors.initials: P
authors.lastname: Garteiser
authors.forename: Sabrina
authors.initials: S
authors.lastname: Doblas
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Daire
authors.forename: Mathilde
authors.initials: M
authors.lastname: Wagner
authors.forename: Helena
authors.initials: H
authors.lastname: Leitao
authors.forename: Valérie
authors.initials: V
authors.lastname: Vilgrain
authors.forename: Ralph
authors.initials: R
authors.lastname: Sinkus
authors.forename: Bernard E
authors.initials: BE
authors.lastname: Van Beers
mesh_terms: D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D014783:Viscosity; D055815:Young Adult