  Recently, there has been an examination of the nonexponential relaxation
profiles of the NMR signal. The exponential relaxation from Bloch-Torrey
equations with constant diffusion coefficients are known to be an
approximation, and research has been in areas that would reproduce
non-exponential relaxation. These would be from statistical models,
phenomenological models, and microscopic models including a recent fractional
derivative approach. In this letter we derive a nonlinear Bloch-Torrey partial
differential equation that has equivalently a non-constant diffusion
coefficient and a linear probability and for which the solution is of a
q-parametrized power-law distribution of the nonextensive Tsallis statistics.
