Pore-to-pore hopping model for the interpretation of the pulsed gradient spin echo attenuation of water diffusion in cell suspension systems

A simplified pore-to-pore hopping model for the two-phase diffusion problem is developed for the analysis of the pulsed gradient spin echo (PGSE) atte nuation of water diffusion in the condensed cell suspension systems. In thi s model, the two phases inside and outside the cells are treated as two dif ferent kinds of pores, and the spin-bearing molecules perform hopping diffu sion between them. The size and the orientations of those two respective po res are considered, and then the diffraction pattern of the PGSE attenuatio n may be well simulated. Nevertheless, the intensity of the characteristic peak decreases with increasing membrane permeability, from which the exchan ge time may be estimated. We then analyze the experimental H-1 PGSE results of the erythrocytes suspension system. The water-residence lifetime in the erythrocyte is obtained to be 10 ms, which is the same as that estimated f rom the two-region approximation. Furthermore, the PGSE attenuation curve o f addition of p-Chloromercuribenzenesulfonate (p-CMBS) is also discussed. I t predicts that the alignment of erythrocytes will become normal to the mag netic field direction after the addition of p-CMBS, and inspection using a light microscope confirms that result.