Rapid Three-Dimensional Myelin Water Fraction Imaging of the Cervical Spinal Cord

INTRODUCTION: The ability to non-invasively and quantitatively assess myelin content in the spinal cord would improve our understanding of a variety of spinal cord-related conditions, as well as enhance our ability to differentially diagnose, treat and monitor them. Currently, little is known about the pathology of myelin in spinal cord disease due to the technical challenges of measuring myelin noninvasively. Multi-component relaxometry can be used to estimate the myelin water fraction (MWF), which has been shown to relate to myelin content. However, imaging a single slice takes between 15 and 25 minutes using conventional multiple-echo spin-echo based techniques (though recent advancements have increased the coverage to 4 or 5 useable 5-mm axial slices). Moreover, these spin-echo methods are sensitive to the in-flow affects of cerebral spinal fluid and off-resonance conditions associated with the multiple airtissue and bone-tissue interfaces and respiratory motion.