A two-region transport model for interpreting T1-T2 measurements in complex systems

James E Maneval; Madison L Nelson; Linn W Thrane; Sarah L Codd; Joseph D Seymour

doi:10.1016/j.jmr.2019.106592

A two-region transport model for interpreting T₁-T₂ measurements in complex systems

J Magn Reson. 2019 Nov:308:106592. doi: 10.1016/j.jmr.2019.106592. Epub 2019 Sep 6.

Authors

James E Maneval¹, Madison L Nelson², Linn W Thrane³, Sarah L Codd³, Joseph D Seymour⁴

Affiliations

¹ Department of Chemical Engineering, Bucknell University, Lewisburg, PA, USA.
² Department of Physics, Montana State University, USA.
³ Department of Mechanical and Industrial Engineering, Montana State University, USA.
⁴ Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, USA. Electronic address: jseymour@montana.edu.

PMID: 31542448
DOI: 10.1016/j.jmr.2019.106592

Abstract

A 1D two region coupled pore model with discrete pore coupling is developed to elucidate the eigenmode interactions in regions with different surface relaxivity. Numerical solution of the model and simulation of the correlation experiment for varying surface relaxivity, pore connectivity and pore size ratio indicate the role of negative eigenmodes and overlap of T₁ and T₂ eigenmodes in generating a time domain signal increase with inversion recovery time, t₁. The eigenmodes and eigenfunctions are considered in detail providing connection between the mathematical model and the diffusion dynamics and spin physics of the system. Physical systems, i.e. a microporous glass bead pack, a cyclopentane/water hydrate former, and beeswax, showing experimentally measured T₁-T₂ time domain signal rise are considered within the limitations of the model.

Keywords: Diffusive coupling; T(1)-T(2) relaxation correlation; Time domain signal; Two-pore model.