Effects of tractography approach on consistency between anatomical and functional connectivity estimates

Diffusion magnetic resonance imaging (dMRI) and resting state functional MRI (RS-fMRI) provide two complementary views of brain circuitry. dMRI facilitates the estimation of anatomical connectivity (AC) through fiber tractography, while RS-fMRI enables the estimation of functional connectivity (FC) based on temporal signal correlations between different brain areas. Recently, there is a methodological push in developing techniques to integrate dMRI and RS-fMRI for multimodal connectivity estimation, success of which highly depends on the consistency between the AC and FC estimates. Using the Human Connectome Project (HCP) data, we show increased AC-FC consistency with streamline tractography on orientation distribution functions (ODFs) compared to using conventional diffusion tensors. We also demonstrate a further, though smaller, improvement when global tractography on ODFs is deployed. Our results suggest that while accurate ODF estimation is important, more attention should be focused on improving tractography methods, which we believe could be highly beneficial.