Diffusion Relaxation Correlation Spectroscopy at Ultra-Short Echo Times Reveals Two Major Compartments in Human Cadaver Brain White Matter

Bibek Dhital¹, Marcel Gratz², Robert Turner¹

Measuring multi-compartmental diffusion in brain tissue and estimating relative fractions of these compartments is complicated due to the influence of relaxation, restriction and exchange. Identifying different compartments with their relative fraction requires a wide range of echo times. Effects of restriction and exchange can be minimized by shortening the diffusion time. We performed Diffusion Relaxation Correlation Spectroscopy (DRCOSY) measurements with very short diffusion time (Δ = 1.2 ms) on excised human corpus callosum. Data were analyzed using a two dimensional inverse Laplace transform. Our results show that diffusion is multi-compartmental and that the fast diffusing compartment has a faster relaxation.