Spinal cord imaging in multiple sclerosis.
Multiple sclerosis (MS) is a chronic neurological condition characterized pathologically by axonal loss, demyelination, inflammation, and gliosis. Magnetic resonance imaging (MRI) has had a major impact on diagnosing MS, understanding the condition, and monitoring the effects of treatments. Recently, spinal cord MRI has received increased attention. Advanced techniques have been used to image the spinal cord, particularly the cervical cord, and measure quantitative parameters such as T1 relaxation time, magnetization transfer ratio, and diffusivity. These metrics show central nervous system abnormalities in MS patients and various correlations with disability and might reflect specific pathological processes. Image analysis techniques have also been developed and combined with high-resolution MRI to measure the cord cross-sectional area (CSA), a metric that relates to cord atrophy. The cord CSA is reduced in MS patients compared to normal controls and correlates with disability. Furthermore, changes in CSA are detectable and correlate with changes in disability. Despite the technical difficulties of performing spinal cord MRI, imaging studies, particularly of the cervical cord, are becoming more common. Significant focus has been placed on measuring cord atrophy, and reproducible techniques have been developed to measure the cervical cord CSA. Spinal cord MRI may provide information about disease progression that is not readily available from brain MRI scans and could be useful in diagnosing MS in some cases, as well as for monitoring the effects of treatments.