# Restricted Diffusion Measurements with Magnetic Resonance

## Standing

Graduate (Masters)

## Type of Proposal

Oral Research Presentation

## Challenges Theme

Building Viable, Healthy and Safe Communities

## Your Location

University of Windsor

## Faculty

Faculty of Science

## Faculty Sponsor

Dan Xiao

## Proposal

In fluids, molecular movement is modelled as random translational motion, known as diffusion. The diffusion coefficient is a measure of the distance a particle travels within a certain amount of time and is related to the fluid property in an uninhibited environment. When the fluid is constrained in a space smaller than the distance it could travel, the inhibited diffusion coefficient, known also as the apparent diffusion coefficient (ADC), is lower. Therefore, the microscopic structure can be inferred by quantitatively analyzing the ADC of the fluid. Magnetic Resonance Imaging (MRI) acquires signal from water in the human body. MRI is well known for its rich soft tissue contrast. It is less well known that quantitative diffusion information could be acquired with magnetic resonance. MR is also capable of measuring the apparent diffusion coefficient in any spatial direction non-invasively, providing insights into the water’s microscopic environment. The effect of the diffusion on the signal can be tuned to acquire a set of data points for different diffusion sensitivities. At higher ADC values, the signal amplitude is lower and vice versa. The ADC value can be calculated via data processing. The technique has been demonstrated with a phantom experiment, where restricted diffusion occurred. ADCs in different directions of the phantom were measured. With the knowledge of the ADC values in different directions, the dimensions of the phantom were estimated using Einstein’s simple particle diffusion model. This technique can be extended to other systems to non-invasively determine their internal microstructures.

Restricted Diffusion Measurements with Magnetic Resonance

In fluids, molecular movement is modelled as random translational motion, known as diffusion. The diffusion coefficient is a measure of the distance a particle travels within a certain amount of time and is related to the fluid property in an uninhibited environment. When the fluid is constrained in a space smaller than the distance it could travel, the inhibited diffusion coefficient, known also as the apparent diffusion coefficient (ADC), is lower. Therefore, the microscopic structure can be inferred by quantitatively analyzing the ADC of the fluid. Magnetic Resonance Imaging (MRI) acquires signal from water in the human body. MRI is well known for its rich soft tissue contrast. It is less well known that quantitative diffusion information could be acquired with magnetic resonance. MR is also capable of measuring the apparent diffusion coefficient in any spatial direction non-invasively, providing insights into the water’s microscopic environment. The effect of the diffusion on the signal can be tuned to acquire a set of data points for different diffusion sensitivities. At higher ADC values, the signal amplitude is lower and vice versa. The ADC value can be calculated via data processing. The technique has been demonstrated with a phantom experiment, where restricted diffusion occurred. ADCs in different directions of the phantom were measured. With the knowledge of the ADC values in different directions, the dimensions of the phantom were estimated using Einstein’s simple particle diffusion model. This technique can be extended to other systems to non-invasively determine their internal microstructures.