Nondestructive Imaging of Myelin and Axonal Architecture by Magnetic Resonance

by Prof. Felix W. Wehrli (Laboratory for Structural NMR Imaging University of Pennsylvania, Perelman School of Medicine, Philadelphia, USA)

Friday 14 Sept 2012, 15:00 → 16:00 Europe/Rome

Aula 4 (Dipartimento di Fisica - Ed. E. Fermi)

Myelin is essential for neuronal current transport. Demyelinating disorders entail disintegration and eventual loss of myelin. Whereas indirect detection techniques for myelin quantification have provided significant insight, they require a number of assumptions to be valid. Direct imaging of myelin by MRI would therefore be preferable but such a goal has been elusive so far. Myelin lipid constituents behave as a liquid crystalline system of super-Lorentzian line-shape, with the majority of protons having an effective lifetimes (T2*)<<100µs. Recent results suggest that direct detection and quantification of myelin via 3D radial encoding MRI may be feasible. Next to noninvasive quantification of myelin, MRI also has potential to probe axonal architecture via q-space displacement imaging, which allows probing cellular structures on a length scale of micrometers. Results obtained with a home-built gradient set yielding 5.000G/cm amplitude are shown to provide good agreement between histologic and q-space derived measurements of axon size.