Transverse relaxivity of particulate MRI contrast media: From theories to experiments

TLDR

Simulations and experiments have characterized particulate MRI contrast agents, focusing on particle size effects. The study defines and measures relaxivity for these agents. Transverse relaxation rate rises with particle diameter up to ~50 nm, then plateaus for larger grains without spin‑echo, but slows with size or shorter echo times in spin‑echo sequences, and large particles show multiexponential decay. © 1991 Academic Press, Inc.

Abstract

Abstract Computer simulations and experimental approach have been used to characterize the properties of particulate MRI contrast agents with special attention paid to the influence of particle size. Up to approximately 50 nm, an increase of the particle diameter leads to a strong enhancement of the transverse magnetization decay rate. For larger grains or aggregates, the decay rate measured without spin‐echo formation reaches a plateau. When observed through a spin‐echo sequence, the transverse magnetization decay rate becomes slower on increasing the particle size or on shortening the echo time. For these large particles, multiexponential decay rates are observed. Definition and measurement of relaxivity in such systems is discussed. © 1991 Academic Press, Inc.