Quantitative magnetic resonance flow and diffusion imaging in porous media

Area of Science:

• Physics
• Materials Science
• Fluid Dynamics

Background:

• Understanding fluid transport in porous media is crucial for various scientific and engineering applications.
• Magnetic Resonance Imaging (MRI) offers non-invasive techniques for probing complex materials.

Purpose of the Study:

• To quantitatively measure water flow and diffusion in model porous media using advanced MRI techniques.
• To validate MRI-derived flow and diffusion parameters against direct measurements.
• To investigate the influence of pore size on water diffusion.

Main Methods:

• Utilized magnetic resonance micro-imaging (μMRI) for high-resolution imaging of water in compacted glass bead samples.
• Employed flow-encoding techniques to map water velocities and diffusion coefficients.
• Analyzed images with a spatial resolution of 117 microns x 117 microns.
• Applied image thresholding to mitigate partial volume effects.

Main Results:

• Achieved good agreement between μMRI-derived volume flow rates and directly measured values.
• Demonstrated excellent correlation between calculated and bulk diffusion coefficients for water.
• Found that the mean diffusion coefficient of water was independent of pore sizes within the 1-3 mm range.
• Showcased the effectiveness of image thresholding for correcting partial volume effects.

Conclusions:

• Magnetic resonance micro-imaging is a reliable method for quantitative flow and diffusion analysis in porous media.
• The diffusion of water in these model porous media is not significantly affected by pore size variations.
• Advanced image processing techniques enhance the accuracy of MRI-based transport measurements.