Correction for fast pseudo-diffusive fluid motion contaminations in diffusion tensor imaging

Sonja Stieb1, Markus Klarhoefer2, Tim Finkenstaedt1

  • 1Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Switzerland.

Insights

Fast pseudo-diffusion contaminates diffusion tensor imaging (DTI) metrics in the brain. An intravoxel incoherent motion (IVIM) model corrects for these signal contaminations, improving accuracy in DTI measurements.

Area of Science:

  • Neuroimaging
  • Biophysics
  • Medical Physics

Background:

  • Diffusion tensor imaging (DTI) measures water diffusion in brain tissue to infer white matter structure.
  • Signal contamination from blood perfusion and cerebrospinal fluid (CSF) movement can affect DTI accuracy.
  • Intravoxel incoherent motion (IVIM) modeling offers a potential method to differentiate diffusion from perfusion/CSF flow.

Purpose of the Study:

  • To quantify the impact of fast pseudo-diffusion (perfusion/CSF) on DTI metrics in healthy brain tissue.
  • To evaluate the effectiveness of an IVIM-based model in correcting for these contaminations.
  • To compare DTI metrics derived from different signal modeling approaches.

Main Methods:

  • Prospective study involving five healthy volunteers at 3 Tesla.
  • Diffusion-weighted imaging acquired with multiple b-values and diffusion directions.
  • DTI metrics (FA, MD) computed using two b-value (2b), monoexponential (mono), and IVIM (bi) models.
  • Region of interest analysis in white matter, gray matter, and ventricles.

Main Results:

  • Significant differences in mean diffusivity (MD) and fractional anisotropy (FA) were observed across all evaluated regions based on the modeling method.
  • The IVIM model yielded lower MD values compared to 2b and monoexponential models.
  • The nucleus caudatus and lateral ventricles showed the largest MD deviations, while the nucleus caudatus and putamen showed significant FA deviations.

Conclusions:

  • Fast pseudo-diffusion significantly affects DTI metric quantification in the brain.
  • The proposed IVIM-based method effectively corrects for signal contaminations from CSF or perfusion.
  • Accurate DTI measurements require accounting for intravoxel incoherent motion, especially in regions with high CSF or perfusion influence.