QUANTITATIVE MAGNETIC-RESONANCE FLOW AND DIFFUSION IMAGING IN POROUS-MEDIA

Quantitative flow and diffusion measurements have been made for water in model porous media, using magnetic resonance micro-imaging methods. The samples consisted of compacted glass beads of various sizes down to 1 mm diameter. Typical flow and diffusion images exhibited a spatia l resolution of 117 mu m X 117 mu m and velocities in the range 1-2 mm /s, Comparison of volume flow Fates calculated from the flow velocity maps with values measured directly yielded good agreement in all cases . There was also good agreement between the mean diffusion coefficient of water calculated from the diffusion maps and the bulk diffusion co efficient for pure water at the same temperature, In addition, the mea n diffusion coefficient did not depend on the pore sizes in the bead d iameter range of 1-3 mm. Our results also show that partial volume eff ects can be compensated by appropriate thresholding of the images prio r to the final Fourier transformation in the flow-encoding dimension.