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Updated: Nov 21, 2025
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Relating diffusion-weighted magnetic resonance imaging of brain white matter to cognitive processing-speed deficits
Muhammad Anisuzzaman Talukder1
1Department of Electrical and Electronic Engineering, Bangladesh University of Engineering and Technology, Dhaka 1205, Bangladesh.
Abstract:
Diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) analyses of diffusion-weighted magnetic resonance imaging (MRI) show that diffusional fractional anisotropy (FA) and kurtosis anisotropy (KA) of water inside brain white matter decrease for schizophrenic patients from that for healthy persons. DTI and DKI are statistical approaches and do not directly point to the underlying neurobiological reasons. In schizophrenia, it is believed that the demyelination of axons-microstructures that constitute the brain white matter-increases lateral diffusion of water and causes defective neural communications, resulting cognitive processing-speed deficits. Here, we use a simple but realistic neurobiological model for brain white matter and solve the Bloch-Torrey equation using numerical finite-element method to find out the underlying reasons of cognitive deficits in schizophrenia. FA and KA are calculated from computationally obtained diffusion-weighted MRI data after a Stejskal-Tanner gradient pulse sequence is applied to a periodic array of tubular axons with circular cross-sections. The calculated FA and KA decrease when the axon walls are more permeable to water, agree with the experimental findings, and correlate with the cognitive processing speeds of healthy persons and schizophrenic patients, and thus, help to understand the underlying reasons of cognitive processing-speed deficits in schizophrenia.
Insights
Schizophrenia is linked to decreased water diffusion anisotropy in brain white matter. A neurobiological model shows increased axon permeability explains these changes and cognitive deficits.
Area of Science:
- Neuroimaging
- Computational Neuroscience
- Biophysics
Background:
- Diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) reveal reduced water diffusion anisotropy (fractional anisotropy and kurtosis anisotropy) in the white matter of individuals with schizophrenia compared to healthy controls.
- These statistical imaging methods do not fully elucidate the underlying neurobiological mechanisms.
- Schizophrenia is hypothesized to involve demyelination, leading to increased water diffusion and impaired neural communication, contributing to cognitive processing speed deficits.
Purpose of the Study:
- To investigate the neurobiological underpinnings of cognitive deficits in schizophrenia using a realistic white matter model.
- To computationally determine the reasons behind reduced diffusion anisotropy and its correlation with cognitive impairments.
Main Methods:
- A neurobiological model of brain white matter was developed.
- The Bloch-Torrey equation was solved using a numerical finite-element method.
- Diffusion-weighted magnetic resonance imaging (MRI) data were computationally simulated using a Stejskal-Tanner gradient pulse sequence on a periodic array of axons.
Main Results:
- Calculated fractional anisotropy (FA) and kurtosis anisotropy (KA) decreased with increased axon wall permeability to water.
- These computational findings align with experimental observations in schizophrenic patients.
- The model's results correlated with cognitive processing speeds in both healthy individuals and those with schizophrenia.
Conclusions:
- Increased axon wall permeability is a likely neurobiological factor contributing to reduced diffusion anisotropy in schizophrenia.
- This model provides insights into the mechanisms underlying cognitive processing speed deficits in schizophrenia.
- The findings bridge computational modeling with neuroimaging data to understand white matter alterations in psychiatric disorders.
