title: Nonparametric pore size distribution using d-PFG: comparison to s-PFG and migration to MRI.
abstract: Here we present the successful translation of a pore size distribution (PSD) estimation method from NMR to MRI. This approach is validated using a well-characterized MRI phantom consisting of stacked glass capillary arrays (GCA) having different diameters. By employing a double pulsed-field gradient (d-PFG) MRI sequence, this method overcomes several important theoretical and experimental limitations of previous single-PFG (s-PFG) based MRI methods by allowing the relative diffusion gradients' direction to vary. This feature adds an essential second dimension in the parameters space, which can potentially improve the reliability and stability of the PSD estimation. To infer PSDs from the MRI data in each voxel an inverse linear problem is solved in conjunction with the multiple correlation function (MCF) framework, which can account for arbitrary experimental parameters (e.g., long diffusion pulses). This scheme makes no a priori assumptions about the functional form of the underlying PSD. Creative use of region of interest (ROI) analysis allows us to create different underlying PSDs using the same GCA MRI phantom. We show that an s-PFG experiment on the GCA phantom fails to accurately reconstruct the size distribution, thus demonstrating the superiority of the d-PFG experiment. In addition, signal simulations corrupted by different noise levels were used to generate continuous and complex PSDs, which were then successfully reconstructed. Finally, owing to the reduced q- or b- values required to measure microscopic PSDs via d-PFG MRI, this method will be better suited to biomedical and clinical applications, in which gradient strength of scanners is limited.
authors: Section on Tissue Biophysics and Biomimetics, PPITS, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA; Department of Biomedical Engineering, The Iby and Aladar Fleischman Faculty of Engineering, Tel-Aviv University, Tel-Aviv, Israel.
authors: Dan
authors: D
authors: Benjamini
authors: Section on Tissue Biophysics and Biomimetics, PPITS, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA; Center for Neuroscience and Regenerative Medicine, Uniform Service University of the Health Sciences, Bethesda, MD, USA.
authors: Michal E
authors: ME
authors: Komlosh
authors: Section on Tissue Biophysics and Biomimetics, PPITS, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA.
authors: Peter J
authors: PJ
authors: Basser
authors: Department of Biomedical Engineering, The Iby and Aladar Fleischman Faculty of Engineering, Tel-Aviv University, Tel-Aviv, Israel. Electronic address: nevouri@eng.tau.ac.il.
authors: Uri
authors: U
authors: Nevo
mesh_terms: D001369:Axons / Q000737:chemistry* / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D019047:Phantoms, Imaging; D016062:Porosity; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography
keywords: Double pulsed field gradient; Empirical; MRI; NMR; Nonparametric; Pore size distribution