title: A phantom for diffusion-weighted MRI (DW-MRI).
abstract: OBJECTIVE
  To develop tissue-equivalent diffusivity materials and build a spherical diffusion phantom which mimics the conditions typically found in biological tissues. Also, to assess the reproducibility of ADC measurements from a whole-body diffusion protocol.
  
  
  METHODS
  Nickel-doped agarose/sucrose gels were manufactured and used to build a spherical diffusion phantom with tissue-equivalent relaxation and diffusion compartments. The temporal stability of the gels was monitored for a period of 8 weeks and, using the same measurements, the reproducibility of ADC was assessed in a 1.5 Tesla (T) clinical system.
  
  
  RESULTS
  The temporal stability of the nickel-doped agarose/sucrose gels diffusion properties was excellent (average coefficient of variation [CV] for ADC in all phantom compartments = 1.27%). The average CV for ADC measurements, excluding the phantom compartments affected by artifacts, was 0.76% showing that the reproducibility of ADC measurements using an EPI DW-MRI protocol is very good.
  
  
  CONCLUSIONS
  Nickel-doped agarose/sucrose gels can be used as reference materials for MRI diffusion measurements and show excellent short-term stability with respect to ADC. A phantom made of these materials can be invaluable in optimizing DW-MRI protocols, developing novel pulse sequences for DW-MRI, or comparing ADC values among field strengths, vendors, and imaging centers.
authors.affiliation: Comprehensive Cancer Imaging Centre (C.C.I.C.), Department of Surgery and Cancer, Hammersmith Campus, Imperial College, London, United Kingdom. ilavdas@imperial.ac.uk
authors.forename: Ioannis
authors.initials: I
authors.lastname: Lavdas
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Behan
authors.forename: Annie
authors.initials: A
authors.lastname: Papadaki
authors.forename: Donald W
authors.initials: DW
authors.lastname: McRobbie
authors.forename: Eric O
authors.initials: EO
authors.lastname: Aboagye
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D051598:Whole Body Imaging / Q000295:instrumentation*
keywords: apparent diffusion coefficient; diffusion phantom; diffusion-weighted MRI; reproducibility; temporal stability; tissue-equivalent diffusivity materials