title: Development of an MRI phantom for diffusion-weighted imaging with independent adjustment of apparent diffusion coefficient values and T2 relaxation times.
abstract: OBJECTIVE
  To design a phantom for diffusion-weighted imaging (DWI) with defined apparent diffusion coefficients (ADC) and T2 relaxation times.
  
  
  METHODS
  Varying concentrations of polyethylene glycol (PEG) were used for the adjustment of diffusivity. T2 relaxation times were tuned by adding of the MR contrast agent gadobutrol. Relaxation times and apparent diffusion coefficients were quantified using a multiecho spin echo sequence and an echo planar imaging (EPI) DWI sequence, respectively, on a 3T clinical scanner.
  
  
  RESULTS
  Increasing concentrations of PEG led to a marked impairment of diffusivity accompanied by only moderate changes of T2 relaxation times. Adding gadobutrol to the PEG solutions allowed for adjustment of transverse relaxation times to predefined values. Thus, a broad range of defined ADC values and T2 relaxation times could be accurately achieved in the final phantom.
  
  
  CONCLUSIONS
  The proposed phantom allows for standardized in vitro studies of DWI methods and protocols. The obtained MR image contrasts are similar to a variety of biological tissues, which can contribute to optimization of imaging techniques with respect to specific clinical questions. Due to the simplicity of design and the accessibility of the contained compounds, this phantom may also serve as a tool for standardization and calibration.
authors.affiliation: Department of Radiology, Diagnostic and Interventional Radiology, Eberhard-Karls University Tübingen, Tübingen, Germany.
authors.forename: Sergios
authors.initials: S
authors.lastname: Gatidis
authors.forename: Holger
authors.initials: H
authors.lastname: Schmidt
authors.forename: Petros
authors.initials: P
authors.lastname: Martirosian
authors.forename: Nina F
authors.initials: NF
authors.lastname: Schwenzer
mesh_terms: D032701:Biomimetics / Q000295:instrumentation*; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: ADC; MRI; PEG; T2 relaxation; diffusion; phantom