Effects of barrier-induced nuclear spin magnetization inhomogeneities on diffusion-attenuated MR signal.
The spatial distribution of the transverse nuclear spin magnetization, appearing in a single compartment with impermeable boundaries in a Stejskal-Tanner gradient pulse MR experiment, is analyzed in detail. At short diffusion times the presence of diffusion-restrictive barriers (membranes) reduces effective diffusivity near the membranes and leads to an inhomogeneous spin magnetization distribution (the edge-enhancement effect). In this case, the signal reveals a quasi-two-compartment behavior and can be empirically modeled remarkably well by a biexponential function. The current results provide a framework for interpreting experimental MR data on various phenomena, including water diffusion in giant axons, metabolite diffusion in the brain, and hyperpolarized gas diffusion in lung airways.
Sukstanskii
A L
AL
Department of Radiology, Washington University, St. Louis, Missouri 63110, USA. alex@wuchem.wustl.edu
Ackerman
J J H
JJ
Yablonskiy
D A
DA
D000818:Animals; D001369:Axons / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D049832:Decapodiformes; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D008168:Lung / Q000378:metabolism; D011659:Pulmonary Gas Exchange; D014867:Water
D014867:Water