title: Generalised calculation of NMR imaging edge effects arising from restricted diffusion in porous media.
abstract: The theoretical problem of how to describe apparent image spin density under conditions of restricted diffusion, given any general gradient sequence, is intrinsically complex. Here we demonstrate a simple approach to calculating the signal and the corresponding density in nuclear magnetic resonance (NMR) imaging experiments by means of an impulse-propagator method based on matrix multiplication. The multiplication scheme bears a natural and straightforward relationship to the k-space sampling, while the matrices themselves are calculated from the eigenmodes of the pore diffusion equation. Good agreement is found between theoretical predictions and the results of micro-imaging experiments on water trapped in rectangular pores whose walls are spaced by 100 microns along the read direction.
authors.affiliation: Department of Physics, Massey University, Palmerston North, New Zealand. p.callaghan@massey.ac.nz
authors.forename: P T
authors.initials: PT
authors.lastname: Callaghan
authors.forename: S L
authors.initials: SL
authors.lastname: Codd
mesh_terms: D004058:Diffusion; D006801:Humans; D007089:Image Enhancement; D009682:Magnetic Resonance Spectroscopy; D008432:Mathematical Computing; D019047:Phantoms, Imaging; D016062:Porosity; D012212:Rheology / Q000706:statistics & numerical data*