Boosting resolution in magnetic resonance imaging to study microstructures in brain and neurodegenerative diseases

GONZALO A. ALVAREZ

Congreso; Alexander von Humboldt Kolleg Current Advances on Neurodegeneration: from Molecular Biology to Translational Medicine.; 2017

Nuclear magne c resonance is a powerful tool for probing the structures of chemical and biological systems. Combined with field gradients it leads to NMR imaging (MRI), a widespread tool in non- invasive examina ons including clinical diagnosis. Sensi vity usually limits MRI's spa al resolu on to tens of micrometers in preclinical se ngs and to milimeters in clinical se ngs. However, other sources of informa on like those delivered by constrained molecular diffusion processes, enable one extract morphological informa on down to micron and sub-micron scales. I will report a series of methods that we have developed to exploit diffusion ? isotropic or anisotropic? to sense morphological parameters in the nm-mm range in biological ssues like in the brain [1-7]. These methods are based on distribu ons of suscep bility-induced magne c field gradients [3,5] and by quantum interferences generated by me reversions induced by MRI techniques [1,2,8,9]. The ensuing methods provide a novel tool to measure restric on lengths in ssue microstructures with a excep onal sensi vity [1,2,4,6,7]. We developed new image contrasts based on parameters that define pore and fiber size distribu ons in ssues (e.g. rat brains and pig spinal cords) [4] and on parameters defining cavity geometries [5] (e.g. fibers in spinal cords). These approaches may be useful for inves ga ng the nature of ssue compartmentaliza on, in non-invasive manners, which eventually could be useful in human and clinical se ngs to study neurodegenera ve diseases.1 G.A. Álvarez, N. Shemesh, and L. Frydman, Phys. Rev. Le . 111, 080404 (2013). 2 N. Shemesh, G.A. Álvarez, and L. Frydman, J. Magn. Reson. 237, 49 (2013).3 G.A. Álvarez, N. Shemesh, and L. Frydman, J. Chem. Phys. 140, 084205 (2014). 4 N. Shemesh, G.A. Álvarez, and L. Frydman, PLoS ONE 10, e0133201 (2015).5 G.A.Álvarez, N. Shemesh, and L. Frydman. Scien fic Reports 7, 3311 (2017). 6 A. Zwick, G.A. Álvarez, and G. Kurizki, Phys. Rev. Applied 5, 014007 (2016). 7 A. Zwick, G.A. Álvarez, and G. Kurizki. Phys. Rev. A 94, 042122 (2016).8 G.A. Álvarez and D. Suter, Phys. Rev. Le . 104, 230403 (2010).9 D. Suter and G.A. Álvarez. Rev. Mod. Phys. 88, 041001 (2016).