Neuroradiological evaluation of demyelinating disease

Abstract

Central nervous system inflammatory demyelinating disease can affect patients across the life span. Consensus definitions and criteria of all of the different acquired demyelinating diseases that fall on this spectrum have magnetic resonance imaging criteria. The advances of both neuroimaging techniques and important discoveries in immunology have produced an improved understanding of these conditions and classification. Neuroimaging plays a central role in the accurate diagnosis, prognosis, disease monitoring and research efforts that are being undertaken in this disease. This review focuses on the imaging spectrum of acquired demyelinating disease.

Can T1w/T2w ratio be used as a myelin‐specific measure in subcortical structures? Comparisons between FSE‐based T1w/T2w ratios, GRASE‐based T1w/T2w ratios and multi‐echo GRASE‐based myelin water fractions

“…Myelin begins to form early in brain development and plays a critical role in signal transmission along axons throughout the central nervous system . Conversely, demyelination impairs signal transmission in a wide range of neurodegenerative diseases, such as multiple sclerosis (MS) and neuromyelitis optica . Precise measurements of myelin content and white matter (WM) microstructural integrity therefore provide important information for understanding both normal brain development and neurodegenerative diseases.…”

In vivo measurement of a new source of contrast, the dipolar relaxation time, T1D, using a modified inhomogeneous magnetization transfer (ihMT) sequence

“…Myelin reflects a very high density of bilayers that are formed by wrapping of oligodendrocyte cell membranes around axons (1). Given that myelin is essential for rapid conduction of nerve impulses and damage to myelin can occur in trauma (2), multiple sclerosis (MS) (3), and other disorders, a sensitive and specific measure of myelin and its properties would be a potentially important clinical and research tool (4,5). Studies of white matter (WM) pathology using simple metrics of MT, such as the MT ratio (MTR), have shown some promise (6), but detailed studies suggest that sensitivity to factors other than myelin reduces diagnostic specificity of MTR (7).…”

MRI differential diagnosis of suspected multiple sclerosis

“…Acute MS plaques may demonstrate enhancement on post-gadolinium T1-weighted imaging within the first 4e6 weeks, which is a reflection of perivascular inflammation and disruption of the bloodebrain barrier. 1 Perilesional inflammatory oedema subsides after a few weeks and remyelination begins; this subacute stage of MS is demonstrated on MRI by the cessation of plaque contrast enhancement (ring, rim, or solid) and may regress on T2-weighted imaging. 2,3 Approximately 80% of acute MS plaques are hypointense on unenhanced T1-weighted imaging, half of which subsequently evolve into permanent low T1-weighted "black holes" representative of axonal loss and scar tissue.…”

“…2,3 Approximately 80% of acute MS plaques are hypointense on unenhanced T1-weighted imaging, half of which subsequently evolve into permanent low T1-weighted "black holes" representative of axonal loss and scar tissue. 1 The T2-weighted hyperintense plaques progressively merge into confluent areas of signal abnormality in advanced stages of MS.…”