Reconstructing contralateral fiber tracts: methodological aspects of cerebello-thalamocortical pathway reconstruction

The identification of pathways connecting the cerebral cortex with subcortical structures is critical to understanding how large-scale brain networks operate. The cerebellum, for example, is known to project numerous axonal bundles to thecerebral cortex passing through the thalamus. This paper focuses on the technical details of cerebello-thalamo-cortical pathway reconstruction using advanced diffusion MRI techniques in humans in vivo. Pathways reconstructed using seed/target placement on super-resolution maps, created with track density imaging (TDI), were compared with those reconstructed by defining regions of interest (ROIs) on non-diffusion weighted images (b0). We observed that the reconstruction of the pathways was more anatomically accurate when using ROIs placed on TDI rather than on b0 maps, while inter-subject variability and reproducibility were similar between the two methods. Diffusion indices along pathways showed a position-dependent specificity that will need to be taken into consideration in future clinical investigations.