title: Hepatocellular carcinoma: IVIM diffusion quantification for prediction of tumor necrosis compared to enhancement ratios.
abstract: OBJECTIVE
  To correlate intra voxel incoherent motion (IVIM) diffusion parameters of liver parenchyma and hepatocellular carcinoma (HCC) with degree of liver/tumor enhancement and necrosis; and to assess the diagnostic performance of diffusion parameters vs. enhancement ratios (ER) for prediction of complete tumor necrosis.
  
  
  METHODS
  In this IRB approved HIPAA compliant study, we included 46 patients with HCC who underwent IVIM diffusion-weighted (DW) MRI in addition to routine sequences at 3.0 T. True diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (PF) and apparent diffusion coefficient (ADC) were quantified in tumors and liver parenchyma. Tumor ER were calculated using contrast-enhanced imaging, and degree of tumor necrosis was assessed using post-contrast image subtraction. IVIM parameters and ER were compared between HCC and background liver and between necrotic and viable tumor components. ROC analysis for prediction of complete tumor necrosis was performed.
  
  
  RESULTS
  79 HCCs were assessed (mean size 2.5 cm). D, PF and ADC were significantly higher in HCC vs. liver (p < 0.0001). There were weak significant negative/positive correlations between D/PF and ER, and significant correlations between D/PF/ADC and tumor necrosis (for D, r 0.452, p < 0.001). Among diffusion parameters, D had the highest area under the curve (AUC 0.811) for predicting complete tumor necrosis. ER outperformed diffusion parameters for prediction of complete tumor necrosis (AUC > 0.95, p < 0.002).
  
  
  CONCLUSIONS
  D has a reasonable diagnostic performance for predicting complete tumor necrosis, however lower than that of contrast-enhanced imaging.
authors.affiliation: Department of Radiology, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA; Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA.
authors.forename: Suguru
authors.initials: S
authors.lastname: Kakite
authors.affiliation: Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA.
authors.forename: Hadrien A
authors.initials: HA
authors.lastname: Dyvorne
authors.affiliation: Department of Radiology, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Lee
authors.affiliation: Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA.
authors.forename: Guido H
authors.initials: GH
authors.lastname: Jajamovich
authors.affiliation: Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA.
authors.forename: Ashley
authors.initials: A
authors.lastname: Knight-Greenfield
authors.affiliation: Department of Radiology, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA; Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, New York, NY 10029, USA.
authors.forename: Bachir
authors.initials: B
authors.lastname: Taouli
keywords: ADC, apparent diffusion coefficient; CE T1WI, contrast-enhanced T1-weighted imaging; D, *pseudodiffusion coefficient (×10−3 mm2/s); D, true diffusion coefficient (×10−3 mm2/s); DW-MRI, diffusion-weighted MRI; Diffusion; Hepatocellular carcinoma; IVIM, intravoxel incoherent motion; Necrosis; PF, perfusion fraction (%); Perfusion