title: Apparent diffusion coefficient is highly reproducible on preclinical imaging systems: Evidence from a seven-center multivendor study.
abstract: OBJECTIVE
  To evaluate between-site agreement of apparent diffusion coefficient (ADC) measurements in preclinical magnetic resonance imaging (MRI) systems.
  
  
  METHODS
  A miniaturized thermally stable ice-water phantom was devised. ADC (mean and interquartile range) was measured over several days, on 4.7T, 7T, and 9.4T Bruker, Agilent, and Magnex small-animal MRI systems using a common protocol across seven sites. Day-to-day repeatability was expressed as percent variation of mean ADC between acquisitions. Cross-site reproducibility was expressed as 1.96 × standard deviation of percent deviation of ADC values.
  
  
  RESULTS
  ADC measurements were equivalent across all seven sites with a cross-site ADC reproducibility of 6.3%. Mean day-to-day repeatability of ADC measurements was 2.3%, and no site was identified as presenting different measurements than others (analysis of variance [ANOVA] P = 0.02, post-hoc test n.s.). Between-slice ADC variability was negligible and similar between sites (P = 0.15). Mean within-region-of-interest ADC variability was 5.5%, with one site presenting a significantly greater variation than the others (P = 0.0013).
  
  
  CONCLUSIONS
  Absolute ADC values in preclinical studies are comparable between sites and equipment, provided standardized protocols are employed.
authors.affiliation: Laboratory of imaging biomarkers, UMR 1149 - CRI, Inserm, Paris Diderot University, Paris, France.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Doblas
authors.affiliation: Division of Radiotherapy and Imaging, Institute of Cancer Research, London, UK.
authors.forename: Gilberto S
authors.initials: GS
authors.lastname: Almeida
authors.affiliation: Personalised Healthcare & Biomarkers, AstraZeneca, Macclesfield, UK.
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Blé
authors.affiliation: Laboratory of imaging biomarkers, UMR 1149 - CRI, Inserm, Paris Diderot University, Paris, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Garteiser
authors.affiliation: Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Hoff
authors.affiliation: CRUK Cambridge Institute, University of Cambridge, Cambridge, UK.
authors.forename: Dominick J O
authors.initials: DJ
authors.lastname: McIntyre
authors.affiliation: Department of Clinical Radiology, Münster University Hospital, Westfälische Wilhelms-Universität, Münster, Germany.
authors.forename: Lydia
authors.initials: L
authors.lastname: Wachsmuth
authors.affiliation: Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Chenevert
authors.affiliation: Department of Clinical Radiology, Münster University Hospital, Westfälische Wilhelms-Universität, Münster, Germany.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Faber
authors.affiliation: CRUK Cambridge Institute, University of Cambridge, Cambridge, UK.
authors.forename: John R
authors.initials: JR
authors.lastname: Griffiths
authors.affiliation: European Institute for Molecular Imaging, Westfälische Wilhelms-Universität, Münster, Germany.
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Jacobs
authors.affiliation: Centre for Imaging Sciences, University of Manchester, Manchester, UK.
authors.forename: David M
authors.initials: DM
authors.lastname: Morris
authors.affiliation: Institute of Cancer Sciences, University of Manchester, Manchester, UK.
authors.forename: James P B
authors.initials: JP
authors.lastname: O'Connor
authors.affiliation: Division of Radiotherapy and Imaging, Institute of Cancer Research, London, UK.
authors.forename: Simon P
authors.initials: SP
authors.lastname: Robinson
authors.affiliation: Laboratory of imaging biomarkers, UMR 1149 - CRI, Inserm, Paris Diderot University, Paris, France.
authors.forename: Bernard E
authors.initials: BE
authors.lastname: Van Beers
authors.affiliation: Centre for Imaging Sciences, University of Manchester, Manchester, UK.
authors.forename: John C
authors.initials: JC
authors.lastname: Waterton
mesh_terms: D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation* / Q000662:veterinary*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005060:Europe; D007089:Image Enhancement / Q000295:instrumentation*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation*; D019047:Phantoms, Imaging / Q000662:veterinary / Q000821:virology; D014481:United States
keywords: apparent diffusion coefficient; imaging biomarker; preclinical MRI; repeatability; reproducibility