title: Intravoxel incoherent motion (IVIM) MR imaging of colorectal liver metastases: are we only looking at tumor necrosis?
abstract: OBJECTIVE
  To determine if intra-voxel incoherent motion diffusion-weighted imaging (IVIM-DWI) parameters, including free molecular-based (D) and perfusion-related (D*, f) diffusion parameters, correlate with the degree of tumor necrosis and viable tumor in colo-rectal cancer (CRC) metastasis.
  
  
  METHODS
  Fifteen patients referred for resection of liver metastases from CRC were retrospectively included in this Institutional Review Board approved study. An IVIM-DWI sequence was performed on a 1.5 Tesla MR imaging system, with 10 b factors (0, 10, 20, 30, 50, 80, 100, 200, 400 and 800 s/mm(2) ). Mean D, D*, f and apparent diffusion coefficient (ADC) values were determined in metastases with a longest diameter above 10 mm. Correlations between the diffusion parameters and the degree of liver tumor necrosis and viable tissue were determined (Spearman).
  
  
  RESULTS
  Correlation between diffusion parameters and histopathological findings was performed in 35 hepatic metastases with a diameter of more than 10 mm (mean size of 17.9 mm; range, 1-68 mm). Both D (r = 0.36; P = 0.035) and ADC (r = 0.4; P = 0.02) correlated with the degree of tumor necrosis but not with viable tumor.
  
  
  CONCLUSIONS
  ADC variation observed in CRC metastases following systemic chemotherapy reflects a specific increase in free-molecular diffusion (D), in itself correlated to the degree of metastasis necrosis.
authors.affiliation: AP-HP, Groupe Henri Mondor Albert Chenevier, Imagerie Medicale, Creteil, France; Universite Paris Est Creteil, Creteil, France.
authors.forename: Melanie
authors.initials: M
authors.lastname: Chiaradia
authors.forename: Laurence
authors.initials: L
authors.lastname: Baranes
authors.forename: Jeanne Tran
authors.initials: JT
authors.lastname: Van Nhieu
authors.forename: Alexandre
authors.initials: A
authors.lastname: Vignaud
authors.forename: Alexis
authors.initials: A
authors.lastname: Laurent
authors.forename: Thomas
authors.initials: T
authors.lastname: Decaens
authors.forename: Anaïs
authors.initials: A
authors.lastname: Charles-Nelson
authors.forename: Pierre
authors.initials: P
authors.lastname: Brugières
authors.forename: Sandrine
authors.initials: S
authors.lastname: Katsahian
authors.forename: Marjane
authors.initials: M
authors.lastname: Djabbari
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Deux
authors.forename: Iradj
authors.initials: I
authors.lastname: Sobhani
authors.forename: Mehdi
authors.initials: M
authors.lastname: Karoui
authors.forename: Alain
authors.initials: A
authors.lastname: Rahmouni
authors.forename: Alain
authors.initials: A
authors.lastname: Luciani
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003106:Colon / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000473:pathology*; D003937:Diagnosis, Differential; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008099:Liver / Q000473:pathology*; D008113:Liver Neoplasms / Q000473:pathology* / Q000556:secondary*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D009038:Motion; D009336:Necrosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: b values; colorectal liver metastases; diffusion weighted imaging; intra-voxel incoherent motion; tumor necrosis