Transverse NMR relaxation as a probe of mesoscopic structure

TL;DR

This paper demonstrates that transverse NMR relaxation is highly sensitive to mesoscopic magnetic susceptibility structures, offering a new contrast mechanism for imaging in biological and porous media.

Contribution

It introduces the concept of using transverse NMR relaxation as a probe for mesoscopic structure, with theoretical and experimental validation across various systems.

Findings

Relaxation rate depends strongly on object shape

Experimental validation with blood samples

Applicable to porous media and biological systems

Abstract

Transverse NMR relaxation in a macroscopic sample is shown to be extremely sensitive to the structure of mesoscopic magnetic susceptibility variations. Such a sensitivity is proposed as a novel kind of contrast in the NMR measurements. For suspensions of arbitrary shaped paramagnetic objects, the transverse relaxation is found in the case of a small dephasing effect of an individual object. Strong relaxation rate dependence on the objects' shape agrees with experiments on whole blood. Demonstrated structure sensitivity is a generic effect that arises in NMR relaxation in porous media, biological systems, as well as in kinetics of diffusion limited reactions.