Multiple sclerosis (MS). Sequence of magnetic resonance imaging (MRI) axial (horizontal) scans showing the internal structure of the head of a patient with MS. Brain MRI is used in the diagnosis and monitoring of MS. This is an inflammatory demyelinating (involving the loss of the nerve insulating material, myelin) condition of the central nervous system (CNS). Symptoms include loss of vision, extreme tiredness, and problems with balance and muscle movement. MS lesions (known as plaques) form in the CNS white matter, here these can be seen as multiple hyperintensities (bright areas) on T2 and FLAIR sequences throughout the cerebral white matter of both hemispheres. Lesions can be seen in this sequence in the corpus callosum (broad band of nerve fibers joining the two brain hemispheres), in the peri-ventricular regions (around the ventricles), in the brainstem, and in the cerebellar hemispheres.