title: Liver cirrhosis: intravoxel incoherent motion MR imaging--pilot study.
abstract: OBJECTIVE
  To retrospectively evaluate a respiratory-triggered diffusion-weighted (DW) magnetic resonance (MR) imaging sequence combined with parallel acquisition to allow the calculation of pure molecular-based (D) and perfusion-related (D*, f) diffusion parameters, on the basis of the intravoxel incoherent motion (IVIM) theory, to determine if these parameters differ between patients with cirrhosis and patients without liver fibrosis.
  
  
  METHODS
  The institutional review board approved this retrospective study; informed consent was waived. IVIM DW imaging was tested on three alkane phantoms, on which the signal-intensity decay curves according to b factors were logarithmically plotted. Ten b factors (0, 10, 20, 30, 50, 80, 100, 200, 400, 800 sec/mm(2)) were used in patients. Patients with documented liver cirrhosis (cirrhotic liver group, n = 12) and patients without chronic liver disease (healthy liver group, n = 25) were included. The mean liver D, D*, and f values were measured and compared with the apparent diffusion coefficient (ADC) computed by using four b values (0, 200, 400, 800 sec/mm(2)). Liver ADC and D, f, and D* parameters were compared between the cirrhotic liver group and healthy liver group. Means were compared by using the Student t test.
  
  
  RESULTS
  Signal-intensity decay curves were monoexponential on phantoms and biexponential in patients. In vivo, mean ADC values were significantly higher than D in the healthy liver group (ADC = 1.39 x 10(-3) mm(2)/sec +/- 0.2 [standard deviation] vs D = 1.10 x 10(-3) mm(2)/sec +/- 0.7) and in the cirrhotic liver group (ADC = 1.23 x 10(-3) mm(2)/sec +/- 0.4 vs D = 1.19 x 10(-3) mm(2)/sec +/- 0.5) (P = .03). ADC and D* were significantly reduced in the cirrhotic liver group compared with those in the healthy liver group (respective P values of .03 and .008).
  
  
  CONCLUSIONS
  Restricted diffusion observed in patients with cirrhosis may be related to D* variations, which reflect decreased perfusion, as well as alterations in pure molecular water diffusion in cirrhotic livers.
authors.affiliation: INSERM Unite U 841, Equipe 17, Molecular Mechanisms of Liver Fibrosis, Creteil, France. alain.luciani@hmn.aphp.fr
authors.forename: Alain
authors.initials: A
authors.lastname: Luciani
authors.forename: Alexandre
authors.initials: A
authors.lastname: Vignaud
authors.forename: Madeleine
authors.initials: M
authors.lastname: Cavet
authors.forename: Jeanne Tran Van
authors.initials: JT
authors.lastname: Nhieu
authors.forename: Ariane
authors.initials: A
authors.lastname: Mallat
authors.forename: Lucile
authors.initials: L
authors.lastname: Ruel
authors.forename: Alexis
authors.initials: A
authors.lastname: Laurent
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Deux
authors.forename: Pierre
authors.initials: P
authors.lastname: Brugieres
authors.forename: Alain
authors.initials: A
authors.lastname: Rahmouni
mesh_terms: D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008099:Liver / Q000473:pathology; D008103:Liver Cirrhosis / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D010865:Pilot Projects; D012189:Retrospective Studies