DTI Analysis Methods: Fibre Tracking and Connectivity

Fibre tracking is a powerful method for obtaining estimates of global structural connections between brain regions from local measurements of diffusion. By post-processing diffusion weighted MRI data, virtual dissections of white matter fibre bundles can be obtained in vivo. Reconstructed fibre tracts are therefore in no way a direct representation of single axons but only represent an integrative pathway of continuous smoothly curved diffusion orientation information. Prior anatomical knowledge on the trajectory of the bundle of interest is indispensable and can be exploited to define regions of interest (ROIs) for tract delineation. This chapter discusses the data requirements and scanning parameters required for reliable tracking results. It introduces the different methods that are available including deterministic, probabilistic, higher order model, automated and global tractography, and how to use them optimally. Finally, strengths and limitations of connectivity analysis based on tractography-derived measures are discussed. If performed and interpreted correctly, fibre tracking may provide useful complementary information in preclinical research and has potential future utility in routine clinical practice.