title: Determination of malignancy and characterization of hepatic tumor type with diffusion-weighted magnetic resonance imaging: comparison of apparent diffusion coefficient and intravoxel incoherent motion-derived measurements.
abstract: OBJECTIVE
  The objective of this study was to compare the value of the apparent diffusion coefficient (ADC) determined with 3 b values and the intravoxel incoherent motion (IVIM)-derived parameters in the determination of malignancy and characterization of hepatic tumor type.
  
  
  METHODS
  Seventy-six patients with 86 solid hepatic lesions, including 8 hemangiomas, 20 lesions of focal nodular hyperplasia, 9 adenomas, 30 hepatocellular carcinomas, 13 metastases, and 6 cholangiocarcinomas, were assessed in this prospective study. Diffusion-weighted images were acquired with 11 b values to measure the ADCs (with b = 0, 150, and 500 s/mm) and the IVIM-derived parameters, namely, the pure diffusion coefficient and the perfusion-related diffusion fraction and coefficient. The diffusion parameters were compared between benign and malignant tumors and between tumor types, and their diagnostic value in identifying tumor malignancy was assessed.
  
  
  RESULTS
  The apparent and pure diffusion coefficients were significantly higher in benign than in malignant tumors (benign: 2.32 [0.87] × 10 mm/s and 1.42 [0.37] × 10 mm/s vs malignant: 1.64 [0.51] × 10 mm/s and 1.14 [0.28] × 10 mm/s, respectively; P < 0.0001 and P = 0.0005), whereas the perfusion-related diffusion parameters did not differ significantly between the 2 groups. The apparent and pure diffusion coefficients provided similar accuracy in assessing tumor malignancy (areas under the receiver operating characteristic curve of 0.770 and 0.723, respectively). In the multigroup analysis, the ADC was found to be significantly higher in hemangiomas than in hepatocellular carcinomas, metastases, and cholangiocarcinomas. In the same manner, it was higher in lesions of focal nodular hyperplasia than in metastases and cholangiocarcinomas. However, the pure diffusion coefficient was significantly higher only in hemangiomas versus hepatocellular and cholangiocellular carcinomas.
  
  
  CONCLUSIONS
  Compared with the ADC, the diffusion parameters derived from the IVIM model did not improve the determination of malignancy and characterization of hepatic tumor type.
authors.affiliation: Laboratory of Physiological and Molecular Imaging of the Abdomen IPMA, INSERM CRB3 - UMR773. sabrina.doblas@inserm.fr
authors.forename: Sabrina
authors.initials: S
authors.lastname: Doblas
authors.forename: Mathilde
authors.initials: M
authors.lastname: Wagner
authors.forename: Helena S
authors.initials: HS
authors.lastname: Leitao
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Daire
authors.forename: Ralph
authors.initials: R
authors.lastname: Sinkus
authors.forename: Valérie
authors.initials: V
authors.lastname: Vilgrain
authors.forename: Bernard E
authors.initials: BE
authors.lastname: Van Beers
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D016477:Artifacts; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008113:Liver Neoplasms / Q000145:classification* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009038:Motion; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D047368:Tumor Burden; D055815:Young Adult