Effect of diffusion-sensitizing gradient timings on the exponential, biexponential and diffusional kurtosis model parameters: in-vivo measurements in the rat thalamus

  • Ludovico Minati
  • Ileana Zucca
  • Gabriella Carcassola
  • Michele Occhipinti
  • Roberto Spreafico
  • Maria Grazia Bruzzone
Research Article



To investigate whether spacing (Δ) and duration (δ) of the diffusion-sensitizing gradient pulses differentially affect exponential (D′), biexponential (D slow, D fast and f slow) and diffusional kurtosis (D and K) model parameters.


Measurements were performed in the rat thalamus for b = 200–3,200 s mm−2, sweeping Δ between 20 and 100 ms at δ = 15 ms, and δ between 15 and 50 ms at Δ = 60 ms. Linear regressions were performed for each model parameter vs. Δ or δ.


Increasing Δ from 20 to 100 ms increases D′ (from 0.64 to 0.70 × 10−3  mm2s−1) and D slow (from 0.26 to 0.33 × 10−3 mm2s−1), reduces K (from 0.57 to 0.53), and has no effects on D fast, f slow or D. Increasing δ from 15 to 50 ms increases D (from 0.80 to 0.88 × 10−3  mm2s−1), and has no effects on the other parameters.


The parameters of the biexponential and diffusional kurtosis models are more sensitive than the exponential model to Δ and δ; however, observed effects are too small to account for the discrepancies found in literature.


Diffusion Time Exponential model Biexponential model Diffusional kurtosis model 


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Copyright information

© ESMRMB 2010

Authors and Affiliations

  • Ludovico Minati
    • 1
    • 2
  • Ileana Zucca
    • 1
    • 2
  • Gabriella Carcassola
    • 1
    • 2
  • Michele Occhipinti
    • 1
    • 2
  • Roberto Spreafico
    • 1
  • Maria Grazia Bruzzone
    • 2
  1. 1.Scientific DepartmentFondazione IRCCS Istituto Neurologico “Carlo Besta”MilanoItaly
  2. 2.Neuroradiology UnitFondazione IRCCS Istituto Neurologico “Carlo Besta”MilanItaly

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