Erythrocyte orientational and cell volume effects on NMR q-space analysis: simulations of restricted diffusion.

Pulsed field-gradient spin echo nuclear magnetic resonance spectroscopy of water diffusing in erythrocytes leads to diffusion interference and diffraction effects, which are visualised in q-space plots of signal intensity versus the magnitude of the spatial wave-number vector q. Interpretation of the features of these q-space plots has been aided by Monte Carlo random walk simulations of diffusion in lattices of virtual erythrocytes. Here, the effect of varying the orientation of the cells with respect to the direction in which diffusion is measured, on the appearance of q-space plots, was investigated, together with the effect of changing the cell volume. We show that these changes are reflected in the appearance of the plots in a way that is diagnostic of the microscopic geometry of the sample.