title: MR elastography of liver tumors: preliminary results.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the potential value of MR elastography (MRE) in the characterization of solid liver tumors.
  
  
  METHODS
  Forty-four liver tumors (14 metastatic lesions, 12 hepatocellular carcinomas, nine hemangiomas, five cholangiocarcinomas, three cases of focal nodular hyperplasia, and one hepatic adenoma) were evaluated with MRE. MRE was performed with a 1.5-T system with a modified phase-contrast gradient-echo sequence to collect axial wave images sensitized along the through-plane motion direction. The tumors were identified on T2- and T1-weighted and gadolinium-enhanced T1-weighted images, and the MRE images were obtained through the tumor. A stiffness map (elastogram) was generated in an automated process consisting of an inversion algorithm. The mean shear stiffness of the tumor was calculated with a manually specified region of interest over the tumor in the stiffness map. The stiffness value of tumor-free hepatic parenchyma was calculated. Statistical analysis was performed on the stiffness values for differentiation of normal liver, fibrotic liver, benign tumors, and malignant tumors.
  
  
  RESULTS
  Malignant liver tumors had significantly greater mean shear stiffness than benign tumors (10.1 kPa vs 2.7 kPa, p < 0.001), fibrotic liver (10.1 kPa vs 5.9 kPa, p < 0.001), and normal liver (10.1 kPa vs 2.3 kPa, p < 0.001). Fibrotic livers had stiffness values overlapping both the benign and the malignant tumors. A cutoff value of 5 kPa accurately differentiated malignant tumors from benign tumors and normal liver parenchyma in this preliminary investigation.
  
  
  CONCLUSIONS
  MR elastography is a promising noninvasive technique for assessing solid liver tumors. Use of MRE may lead to new quantitative tissue characterization parameters for differentiating benign and malignant liver tumors.
authors.affiliation: Department of Radiology, Mayo Clinic and Foundation, 200 First St. SW, Opus Bldg., Rochester, MN 55905, USA.
authors.forename: Sudhakar K
authors.initials: SK
authors.lastname: Venkatesh
authors.forename: Meng
authors.initials: M
authors.lastname: Yin
authors.forename: James F
authors.initials: JF
authors.lastname: Glockner
authors.forename: Naoki
authors.initials: N
authors.lastname: Takahashi
authors.forename: Philip A
authors.initials: PA
authors.lastname: Araoz
authors.forename: Jayant A
authors.initials: JA
authors.lastname: Talwalkar
authors.forename: Richard L
authors.initials: RL
authors.lastname: Ehman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity