Taking a closer look at seemingly normal brain tissue with myelin water imaging in patients with multiple sclerosis

Takeaway

  • Myelin water imaging can detect diffuse tissue damage in white matter which appears healthy on traditional scans in patients with multiple sclerosis (MS) and was associated with measures of cognitive impairment.

Why this matters

  • Up to 70% of people with MS experience cognitive impairment.

  • The clinicoradiological paradox refers to the lack of association between the radiological hallmark of MS – myelin lesions visualized on conventional magnetic resonance imaging (MRI) scans – and clinical measures of cognitive and physical impairment.

    • A plausible explanation for this paradox is that the type of tissue damage driving cognitive disability is not detected using conventional imaging techniques.

    • Postmortem evidence suggests that normal-appearing white matter (NAWM) can be diffusely demyelinated without the presence of myelin lesions on MRI.

  • Myelin water imaging is a sensitive MRI technique that measures the T2 relaxation signal from water in the myelin bilayers of the brain, enabling quantitative assessment of myelin in vivo and potentially able to detect demyelination in NAWM.