Size distribution imaging by Non-Uniform Oscillating-Gradient Spin Echo (NOGSE) MRI

NOAM SHEMESH; GONZALO A. ALVAREZ; LUCIO FRYDMAN

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2015 vol. 10 p. 133201 - 133201

1932-6203

Objects making up complex porous systems in Nature usually span a range of sizes. Thesesize distributions play fundamental roles in defining the physicochemical, biophysical andphysiological properties of a wide variety of systems ? ranging from advanced catalyticmaterials to Central Nervous System diseases. Accurate and noninvasive measurementsof size distributions in opaque, three-dimensional objects, have thus remained long-standing and important challenges. Herein we describe how a recently introduced diffusion-based magnetic resonance methodology, Non-Uniform-Oscillating-Gradient-Spin-Echo(NOGSE), can determine such distributions noninvasively. The method relies on its abilityto probe confining lengths with a (length)6 parametric sensitivity, in a constant-time, con-stant-number-of-gradients fashion; combined, these attributes provide sufficient sensitivityfor characterizing the underlying distributions in μm-scaled cellular systems. Theoreticalderivations and simulations are presented to verify NOGSE?s ability to faithfully reconstructsize distributions through suitable modeling of their distribution parameters. Experiments inyeast cell suspensions ? where the ground truth can be determined from ancillary micros-copy ? corroborate these trends experimentally. Finally, by appending to the NOGSE proto-col an imaging acquisition, novel MRI maps of cellular size distributions were collectedfrom a mouse brain. The ensuing micro-architectural contrasts successfully delineated dis-tinctive hallmark anatomical sub-structures, in both white matter and gray matter tissues, ina non-invasive manner. Such findings highlight NOGSE?s potential for characterizing aber-rations in cellular size distributions upon disease, or during normal processes such asdevelopment.