Comparison of block and event-related experimental designs in diffusion-weighted functional MRI

J Magn Reson Imaging. 2014 Aug;40(2):367-75. doi: 10.1002/jmri.24353. Epub 2013 Oct 29.

Abstract

Purpose: To compare diffusion-weighted functional magnetic resonance imaging (DfMRI), a novel alternative to the blood oxygenation level-dependent (BOLD) contrast, in a functional MRI experiment.

Materials and methods: Nine participants viewed contrast reversing (7.5 Hz) black-and-white checkerboard stimuli using block and event-related paradigms. DfMRI (b = 1800 mm/s(2)) and BOLD sequences were acquired. Four parameters describing the observed signal were assessed: percent signal change, spatial extent of the activation, the Euclidean distance between peak voxel locations, and the time-to-peak of the best fitting impulse response for different paradigms and sequences.

Results: The BOLD conditions showed a higher percent signal change relative to DfMRI; however, event-related DfMRI showed the strongest group activation (t = 21.23, P < 0.0005). Activation was more diffuse and spatially closer to the BOLD response for DfMRI when the block design was used. DfMRIevent showed the shortest TTP (4.4 ± 0.88 sec).

Conclusion: The hemodynamic contribution to DfMRI may increase with the use of block designs.

Keywords: BOLD; DfMRI; diffusion; experimental design; fMRI; visual cortex.

Publication types

  • Comparative Study
  • Review

MeSH terms

  • Adult
  • Algorithms*
  • Brain Mapping / methods*
  • Diffusion Magnetic Resonance Imaging / methods*
  • Evoked Potentials, Visual / physiology*
  • Female
  • Humans
  • Image Enhancement / methods
  • Image Interpretation, Computer-Assisted / methods*
  • Male
  • Reproducibility of Results
  • Research Design*
  • Sensitivity and Specificity
  • Visual Cortex / physiology*
  • Young Adult