In vivo tensor-valued diffusion MRI of focal demyelination in white and deep grey matter of rodents.
BACKGROUND
Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease leading to damage of white matter (WM) and grey matter (GM). Magnetic resonance imaging (MRI) is the modality of choice to assess brain damage in MS, but there is an unmet need in MRI for achieving higher sensitivity and specificity to MS-related microstructural alterations in WM and GM.


OBJECTIVE
To explore whether tensor-valued diffusion MRI (dMRI) can yield sensitive microstructural read-outs for focal demyelination in cerebral WM and deep GM (DGM).


METHODS
Eight rats underwent L-α-Lysophosphatidylcholine (LPC) injections in the WM and striatum to introduce focal demyelination. Multimodal MRI was performed at 7 Tesla after 7 days. Tensor-valued dMRI was complemented by diffusion tensor imaging, quantitative MRI and proton magnetic resonance spectroscopy (MRS).


RESULTS
Quantitative MRI and MRS confirmed that LPC injections caused inflammatory demyelinating lesions in WM and DGM. Tensor-valued dMRI illustrated a significant decline of microscopic fractional anisotropy (µFA) in both LPC-treated WM and DGM (P < 0.005) along with a marked increase of isotropic kurtosis (MKI) in DGM (P < 0.0001).


CONCLUSION
Tensor-valued dMRI bears considerable potential for microstructural imaging in MS, suggesting a regional µFA decrease may be a sensitive indicator of MS lesions, while a regional MKI increase may be particularly sensitive in detecting DGM lesions of MS.
['He|Yi|Y|', 'Aznar|Susana|S|', 'Siebner|Hartwig R|HR|', 'Dyrby|Tim B|TB|']
D000818:Animals D016880:Anisotropy D001921:Brain D038524:Diffusion Magnetic Resonance Imaging D056324:Diffusion Tensor Imaging D066128:Gray Matter D009103:Multiple Sclerosis D051381:Rats D012377:Rodentia D066127:White Matter
Tensor-valued diffusion Microscopic fractional anisotropy Isotropic kurtosis DTI Deep grey matter demyelination Metabolic alterations