A general method for optimizing tissue discrimination in magnetic resonance imaging

The basic partial differential formulation for small differences has been applied to the equations for the inversion recovery and saturation recovery sequences with spin-echo rephase pulses and the spin-echo sequence itself. The result is a generalized expression which is proportional to tissue discrimination expressed as the signal-difference-to-noise ratio for a pair of tissues. The expression is a function of the fractional differences in the tissue relaxation times and proton densities, T1, T2, and n, respectively, and the sequence parameters TR and TI, or TE. From it can be derived the conditions which lead to optimum tissue discrimination for a given pulse sequence. It is also possible to predict the optimum pulse sequence to use for any pair of tissues of interest. The method requires a knowledge of the fractional differences in T1, T2, and n for both tissues.