Functional MRI of the Spinal Cord: Diffusion Weighted, Diffusion Tensor Imaging, and Fiber Tractography

In spine imaging, while MRI is the best imaging modality, the conventional MR techniques do not appear to differentiate the various pathophysiological processes such as edema from loss of axonal integrity, and are therefore limited to providing limited anatomic information about the spinal cord parenchyma. The water content or hemorrhagic content, as assessed on the conventional MRI sequences, do not necessarily reflect the status of the white matter tracts at, and adjacent to, the level of spinal cord affliction and consequently the functional status of the spinal cord is not well assessed [1]. Diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), fiber tractography (FT), and blood oxygen level dependent functional magnetic resonance imaging (BOLD fMRI) in the brain have seen progressive translation from the laboratory to the clinic in the past decade. At our institution, DWI, DTI, and presurgical mapping of the eloquent brain regions using BOLD fMRI is commonplace. More recently, these challenging advanced MR imaging techniques have been applied to an even more challenging part of the central nervous system, namely the spinal cord. The advanced MR imaging techniques such as diffusion imaging, including DTI and fiber tractography, and BOLD fMRI have the potential of providing physiologic information and measures/biomarkers of neuronal integrity which may greatly impact our understanding and management of a variety of various spinal cord disease processes. There are major challenges to imaging the spinal cord using these techniques. Despite these challenges, there are a number of potential clinical applications for DTI, FT, and fMRI in the spinal cord. These include but are certainly not limited to.