Differentiating between axonal damage and demyelination in healthy aging by combining diffusion-tensor imaging and diffusion-weighted spectroscopy in the human corpus callosum at 7 T

Francesca Branzoli (1, 2) , Ece Ercan (3) , Romain Valabrègue (1, 2) , Emily T. Wood (4) , Mathijs Buijs (3) , Andrew Webb (3) , Itamar Ronen (3)

1 CENIR - Plateforme de neuroimagerie CENIR = Center for NeuroImaging Research-Human MRI Neuroimaging core facility for clinical research [ICM Paris]
2 ICM - Institut du Cerveau et de la Moëlle Epinière = Brain and Spine Institute
3 C. J. Gorter Center for High Field MRI
4 Neuroimmunology Branch

Diffusion-tensor imaging and single voxel diffusion-weighted magnetic resonance spectroscopy were used at 7T to explore in vivo age-related microstructural changes in the corpus callosum. Sixteen healthy elderly (age range 60–71 years) and 13 healthy younger controls (age range 23–32 years) were included in the study. In healthy elderly, we found lower water fractional anisotropy and higher water mean diffusivity and radial diffusivity in the corpus callosum, indicating the onset of demyelination processes with healthy aging. These changes were not associated with a concomitant significant difference in the cytosolic diffusivity of the intra-axonal metabolite N-acetylaspartate (p = 0.12), the latter representing a pure measure of intra-axonal integrity. It was concluded that the possible intra-axonal changes associated with normal aging processes are below the detection level of diffusion-weighted magnetic resonance spectroscopy in our experiment (e.g., smaller than 10%) in the age range investigated. Lower axial diffusivity of total creatine was observed in the elderly group (p = 0.058), possibly linked to a dysfunction in the energy metabolism associated with a deficit in myelin synthesis.

Mots clés: Diffusion-weighted MRS; Intracellular metabolites; DTI; Healthy aging; White matter

Domaines: Neurobiologie

Francesca Branzoli, Ece Ercan, Romain Valabrègue, Emily T. Wood, Mathijs Buijs, et al.. Differentiating between axonal damage and demyelination in healthy aging by combining diffusion-tensor imaging and diffusion-weighted spectroscopy in the human corpus callosum at 7 T. Neurobiology of Aging, 2016, 47, pp.210-217. ⟨10.1016/j.neurobiolaging.2016.07.022⟩. ⟨hal-01376793⟩