Novel MR contrasts to reveal more about the brain

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Diffusion imaging

Diffusion is a random process that results from the thermal translational motion of molecules. In biologic systems, the diffusing medium is not of infinite extent, and molecular diffusion is restricted by intra- and extracellular boundaries. This raises the possibility that the measurement of water diffusion might provide a means of probing cellular integrity and pathology.

In routine MR imaging, diffusion effects contribute little to overall signal intensity, causing signal attenuation of no

Magnetization transfer imaging

The principal concept of magnetization transfer imaging (MTI) involves the exchange of magnetization between three separate proton pools: (1) free protons in bulk water; (2) tightly bound protons on macromolecules; and (3) transiently bound hydration layer protons.

The protons that are tightly bound to macromolecules, because of their immobility, have a broad MR peak and a short T2. They are, therefore, invisible to conventional MR imaging. MTI offers an insight into this macromolecular

Summary

The advanced imaging techniques described in this article have only recently been applied to patients with focal epilepsy, and corroboratory evidence, particularly histopathologic data, is lacking. Preliminary work suggests that the interrogation of microstructural aspects of cerebral tissue, so far unexplored with conventional MR imaging, may prove beneficial. Based on the voxel-based studies of patients with cryptogenic focal epilepsy, T2 mapping and DIR were the most sensitive of the

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