Related Experiment Video
Updated: Jun 23, 2026
17:06
Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging
Published on: November 8, 2012
A multi-compartmental SE-BOLD interpretation for stimulus-related signal changes in diffusion-weighted functional MRI
Jeff Kershaw1, Moyoko Tomiyasu, Kenichi Kashikura
1Department of Biophysics, Molecular Imaging Centre, National Institute of Radiological Sciences, Anagawa, Inage-ku, Chiba, Japan.
NMR in Biomedicine
|May 7, 2009
Summary
Diffusion-weighted functional MRI reveals distinct signal changes related to brain activity. This study proposes a new interpretation of spin-echo BOLD signals, differentiating contributions from vascular and tissue compartments for better haemodynamic insights.
Area of Science:
- Neuroimaging
- Biophysics
- Functional Magnetic Resonance Imaging
Background:
- Diffusion-weighted functional MRI (fMRI) is sensitive to physiological changes during neural activity.
- Understanding the origin of stimulus-induced signal changes in fMRI is crucial for accurate interpretation.
- Spin-echo BOLD (SE-BOLD) signals are influenced by diffusion properties and vascular contributions.
Purpose of the Study:
- To propose a novel interpretation of stimulus-induced signal changes in diffusion-weighted fMRI.
- To differentiate the contributions of vascular and tissue compartments to the SE-BOLD signal.
- To investigate the relationship between diffusion weighting and the characteristics of the fMRI response.
Main Methods:
- Acquisition of T(2)-weighted spin-echo echo-planar images at varying diffusion-weightings (b-values) during visual stimulation.
- Analysis of functional time-courses, focusing on stimulus-correlated responses and post-stimulus undershoot (PSU).
- Application of a three-compartment signal model (vascular, fast-diffusing tissue, slow-diffusing tissue) to decompose signal changes.
Main Results:
- Stimulus-induced signal changes decomposed into distinct contributions from vascular, fast-diffusion, and slow-diffusion compartments.
- Fast-diffusion phase showed a significant PSU, while the slow-diffusion phase exhibited a reproducible, stimulus-correlated response with minimal undershoot.
- Different trends in response amplitude and PSU were observed across varying b-values.
Conclusions:
- The study proposes that fast- and slow-diffusing molecules reflect susceptibility changes in different vessel sizes (arteriole/venule vs. capillary).
- This compartmental decomposition offers a new interpretation of the SE-BOLD effect in diffusion-weighted fMRI.
- Diffusion-weighted SE-BOLD imaging may provide more nuanced information on haemodynamic and neuronal responses.
