title: Optimization of intra-voxel incoherent motion imaging at 3.0 Tesla for fast liver examination.
abstract: BACKGROUND
  Optimization of multi b-values MR protocol for fast intra-voxel incoherent motion imaging of the liver at 3.0 Tesla.
  
  
  METHODS
  A comparison of four different acquisition protocols were carried out based on estimated IVIM (DSlow , DFast , and f) and ADC-parameters in 25 healthy volunteers. The effects of respiratory gating compared with free breathing acquisition then diffusion gradient scheme (simultaneous or sequential) and finally use of weighted averaging for different b-values were assessed. An optimization study based on Cramer-Rao lower bound theory was then performed to minimize the number of b-values required for a suitable quantification. The duration-optimized protocol was evaluated on 12 patients with chronic liver diseases
  
  
  RESULTS
  No significant differences of IVIM parameters were observed between the assessed protocols. Only four b-values (0, 12, 82, and 1310 s.mm(-2) ) were found mandatory to perform a suitable quantification of IVIM parameters. DSlow and DFast significantly decreased between nonadvanced and advanced fibrosis (P < 0.05 and P < 0.01) whereas perfusion fraction and ADC variations were not found to be significant.
  
  
  CONCLUSIONS
  Results showed that IVIM could be performed in free breathing, with a weighted-averaging procedure, a simultaneous diffusion gradient scheme and only four optimized b-values (0, 10, 80, and 800) reducing scan duration by a factor of nine compared with a nonoptimized protocol. Preliminary results have shown that parameters such as DSlow and DFast based on optimized IVIM protocol can be relevant biomarkers to distinguish between nonadvanced and advanced fibrosis.
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.forename: Hervé
authors.initials: H
authors.lastname: Saint-Jalmes
authors.forename: Cecile
authors.initials: C
authors.lastname: Rabrait
authors.forename: Frank
authors.initials: F
authors.lastname: Pilleul
authors.forename: Olivier
authors.initials: O
authors.lastname: Guillaud
authors.forename: Jérôme
authors.initials: J
authors.lastname: Dumortier
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Scoazec
authors.forename: Olivier
authors.initials: O
authors.lastname: Beuf
mesh_terms: D000328:Adult; D000465:Algorithms; D016477:Artifacts; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008099:Liver / Q000473:pathology*; D008103:Liver Cirrhosis / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009038:Motion; D015203:Reproducibility of Results; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity
keywords: IVIM; MRI; liver