title: Detecting compartmental non-Gaussian diffusion with symmetrized double-PFG MRI.
abstract: Diffusion in tissue and porous media is known to be non-Gaussian and has been used for clinical indications of stroke and other tissue pathologies. However, when conventional NMR techniques are applied to biological tissues and other heterogeneous materials, the presence of multiple compartments (pores) with different Gaussian diffusivities will also contribute to the measurement of non-Gaussian behavior. Here we present symmetrized double PFG (sd-PFG), which can separate these two contributions to non-Gaussian signal decay as having distinct angular modulation frequencies. In contrast to prior angular d-PFG methods, sd-PFG can unambiguously extract kurtosis as an oscillation from samples with isotropic or uniformly oriented anisotropic pores, and can generally extract a combination of compartmental anisotropy and kurtosis. The method further fixes its sensitivity with respect to the time dependence of the apparent diffusion coefficient. We experimentally demonstrate the measurement of the fourth cumulant (kurtosis) of diffusion and find it consistent with theoretical predictions. By enabling the unambiguous identification of contributions of compartmental kurtosis to the signal, sd-PFG has the potential to help identify the underlying micro-structural changes corresponding to current kurtosis based diagnostics, and act as a novel source of contrast to better resolve tissue micro-structure.
authors.affiliation: Schlumberger-Doll Research, Cambridge, MA, 02139, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Paulsen
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02215, USA.|Section on Tissue Biophysics and Biomimetics, PPITS, NICHD, National Institutes of Health, Bethesda, MD, 20892, USA.|Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA.|Department of Physics, Boğaziçi University, Bebek, 34342, İstanbul, Turkey.
authors.forename: Evren
authors.initials: E
authors.lastname: Özarslan
authors.affiliation: Section on Tissue Biophysics and Biomimetics, PPITS, NICHD, National Institutes of Health, Bethesda, MD, 20892, USA.|Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA.
authors.forename: Michal E
authors.initials: ME
authors.lastname: Komlosh
authors.affiliation: Section on Tissue Biophysics and Biomimetics, PPITS, NICHD, National Institutes of Health, Bethesda, MD, 20892, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Basser
authors.affiliation: Schlumberger-Doll Research, Cambridge, MA, 02139, USA.
authors.forename: Yi-Qiao
authors.initials: YQ
authors.lastname: Song
mesh_terms: D000465:Algorithms; D027761:Asparagus Plant / Q000737:chemistry*; D003198:Computer Simulation; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008954:Models, Biological; D008956:Models, Chemical; D015233:Models, Statistical; D016011:Normal Distribution; D010539:Permeability; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Kurtosis; compartment shape anisotroy; diffusion correlation; double diffusion encoding; double wavevector; microscopic anisotropy; non-Gaussian diffusion; restricted diffusion