Evidence of red cell alignment in the magnetic field of an NMR spectrometer based on the diffusion tensor of water

The alignment of human erythrocytes in aqueous suspensions in the magnetic field B-0 (called the z-direction) of an NMR spectrometer was shown by calculating the diffusion tensor for water in the sample. The diffusion was measured using a pulsed-held-gradient spin-echo NMR method. The extent of diffusion anisotropy for water was exemplified by the values of the apparent diffusion coefficients with erythrocytes of normal shape and volume: for a typical experiment the values for the x-, y-, and z-directions were (6.88 +/- 0.17) x 10(-10), (7.07 +/- 0.17) x 10(-10), and (10.20 +/- 0.17) x 10(-10) m(2) s(-1), respectively. Cells in hypo- and hyperosmotic media were also studied and they too showed the anisotropy of the apparent diffusion coefficients but the extents were different. A new method of data analysis was developed using the Standard Add-On Packages in a Mathematica program, The experimental findings support evidence of erythrocyte alignment that was previously obtained with a high-field-gradient q-space method. (C) 2000 Academic Press.