title: Eliminating the blood-flow confounding effect in intravoxel incoherent motion (IVIM) using the non-negative least square analysis in liver.
abstract: Tissue perfusion measurements using intravoxel incoherent motion (IVIM) diffusion-MRI are of interest for investigations of liver pathologies. A confounding factor in the perfusion quantification is the partial volume between liver tissue and large blood vessels. The aim of this study was to assess and correct for this partial volume effect in the estimation of the perfusion fraction.
  
  
  
  MRI experiments were performed at 3 Tesla with a diffusion-MRI sequence at 12 b-values. Diffusion signal decays in liver were analyzed using the non-negative least square (NNLS) method and the biexponential fitting approach.
  
  
  
  In some voxels, the NNLS analysis yielded a very fast-decaying component that was assigned to partial volume with the blood flowing in large vessels. Partial volume correction was performed by biexponential curve fitting, where the first data point (b = 0 s/mm2) was eliminated in voxels with a very fast-decaying component. Biexponential fitting with partial volume correction yielded parametric maps with perfusion fraction values smaller than biexponential fitting without partial volume correction.
  
  
  
  The results of the current study indicate that the NNLS analysis in combination with biexponential curve fitting allows to correct for partial volume effects originating from blood flow in IVIM perfusion fraction measurements. Magn Reson Med 77:310-317, 2017. © 2016 Wiley Periodicals, Inc.
authors.affiliation: INSERM, UMR 1099, Rennes, France.|Université de Rennes 1, LTSI, Rennes, France.
authors.forename: Giulio
authors.initials: G
authors.lastname: Gambarota
authors.affiliation: INSERM, UMR 1099, Rennes, France.|Université de Rennes 1, LTSI, Rennes, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Hitti
authors.affiliation: Université de Lyon, CREATIS; CNRS UMR 5220; Inserm U1044; INSA-Lyon, Université Lyon 1, Villeurbanne, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Leporq
authors.affiliation: INSERM, UMR 1099, Rennes, France.|Université de Rennes 1, LTSI, Rennes, France.|CRLCC, Centre Eugène Marquis, Rennes, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Saint-Jalmes
authors.affiliation: Université de Lyon, CREATIS; CNRS UMR 5220; Inserm U1044; INSA-Lyon, Université Lyon 1, Villeurbanne, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Beuf
mesh_terms: D000465:Algorithms; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008099:Liver / Q000098:blood supply / Q000000981:diagnostic imaging*; D018810:Magnetic Resonance Angiography / Q000379:methods*
keywords: IVIM; MRI; NNLS; blood flow; diffusion; intravoxel incoherent motion; liver; perfusion