Magnetic resonance T₁-T₂* and T_1ρ-T₂* relaxation correlation measurements in solid-like materials with...

Magnetic resonance T₁-T₂* relaxation correlation is a newly emerging and powerful tool to study the structure and dynamics of materials. However, the T₁-T₂* of solid-like materials may consist of a linear combination of exponential decays and non-exponential decays, and the traditional methods for processing T₁-T₂ data would be not applicable. In this paper, a method of processing T₁-T₂* data with non-exponential decays was proposed. The critical idea is to decompose the data into two sub-datasets, exponential decays and non-exponential decays, employing a non-linear fitting method, and then to invert the sub-datasets and to combine the inversion results. We also introduce a related relaxation correlation measurement, T_1ρ-T₂*, for examination of solid-like materials. The same data processing strategy as for T₁-T₂* was implemented. The effectiveness of the proposed method for processing non-exponential data, Sinc Gaussian and Gaussian decay, was validated with simulation and experiment. The results showed that the proposed method recovers T₁-T₂* and T_1ρ-T₂* spectra with accurate relative signal intensities. The proposed method provides a platform for further development of MR methods applied to solid-like materials. These relaxation correlations are well suited to measuring composition of mixtures, with solid components in the mixture.