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BACKGROUND: Clinical examination is the gold standard for surgical indication. Electromyogram and conventional MRI are insufficient to understand the highly variable clinical presentation of neonatal brachial plexus (BP) lesions. Diffusion Tensor Imaging is based on motion of water molecules and can explore nerve function. PURPOSE: This pilot study of healthy subjects aimed to develop a new method for BP exploration using MRI. The main objective was to obtain complete and accurate BP mapping using DTI and MRI tractography. METHODS: Six healthy volunteers had MRI (3T PRISMA) with anatomical 3D STIR, SPACE and RESOLVE diffusion sequences. Image analysis and processing was performed with MATLAB software. Diffusion parametric maps of fractional anisotropy (FA) were extracted from RESOLVE acquisitions. A reproducible method for root volume and angle measurements was created using 3DSlicer. Regions Of Interest were segmented on Mean B0 sequences. FA measurements were obtained with ROI on Mean B0 sequences. RESULTS: RESOLVE sequence was adapted to the BP. Mean FA was 0.30. Angle measurements on 3D STIR SPACE sequences showed increasing values from proximal to distal roots with an ICC of 0.6. Volume measurements on anatomical sequences varied widely from one root to another but no significant difference was shown on laterality. CONCLUSION: A new and reproducible method for BP exploration was developed using MRI RESOLVE diffusion sequences. Complete mapping was obtained despite low track density imaging resolution. The whole BP was visualized. Extraction of diffusion, volume and angle parameters of the plexus roots, and script creation for image processing was adapted to the healthy BP.

Objective: We employed diffusion-weighted magnetic resonance spectroscopy (DW-MRS), which allows to measure in vivo the diffusion properties of metabolites, to explore the functional neuro-axonal damage and the ongoing energetic dysregulation in multiple sclerosis (MS). Methods: Twenty-five patients with MS and 18 healthy controls (HC) underwent conventional magnetic resonance imaging (MRI) and DW-MRS. The apparent diffusion coefficient (ADC) of total N-acetyl-aspartate (tNAA) and creatine–phosphocreatine (tCr) were measured in the parietal normal-appearing white matter (NAWM) and in the thalamic grey matter (TGM). Multiple regressions were used to compare metabolite ADCs between groups and to explore clinical correlations. Results: In patients compared with HCs, we found a reduction in ADC(tNAA) in the TGM, reflecting functional and structural neuro-axonal damage, and in ADC(tCr) in both NAWM and TGM, possibly reflecting a reduction in energy supply in neurons and glial cells. Metabolite ADCs did not correlate with tissue atrophy, lesional volume or metabolite concentrations, while in TGM metabolite ADCs correlated with clinical scores. Conclusion: DW-MRS showed a reduction in tCr diffusivity in the normal-appearing brain of patients with MS, which might reflect a state of ongoing energy dysregulation affecting neurons and/or glial cells. Reversing this energy dysregulation before neuro-axonal degeneration arises may become a key objective in future neuroprotective strategies.