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Fluid-attenuated inversion recovery (FLAIR) is a magnetic resonance imaging sequence with an inversion recovery set to null fluids. For example, it can be used in brain imaging to suppress cerebrospinal fluid (CSF) effects on the image, so as to bring out the periventricular hyperintense lesions, such as multiple sclerosis (MS) plaques. [ 1 ]
Demyelinating diseases are traditionally classified into two types: demyelinating myelinoclastic diseases and demyelinating leukodystrophic diseases. In the first group, a healthy and normal myelin is destroyed by toxic substances, chemicals, or autoimmune reactions.
Demyelinating lesions begin with the appearance of some areas named NAWM (normal appearing white matter) which despite its name, is abnormal in several parameters. These areas show axonal transections and stressed oligodendrocytes (the cells responsible for maintaining the myelin), and randomly, they show clusters of activated microglia named ...
MRI scans showing hyperintensities. A hyperintensity or T2 hyperintensity is an area of high intensity on types of magnetic resonance imaging (MRI) scans of the brain of a human or of another mammal that reflect lesions produced largely by demyelination and axonal loss.
The first study of the human brain at 3.0 T was published in 1994, [13] and in 1998 at 8 T. [14] Studies of the human brain have been performed at 9.4 T (2006) [15] and up to 10.5 T (2019). [16] Paul Lauterbur and Sir Peter Mansfield were awarded the 2003 Nobel Prize in Physiology or Medicine for their discoveries concerning MRI.
Normally two different kind of lesions appear on a normal MRI: T2-hypertense lesions and T1-hypointense. The first one are demyelinating lesions and appear brighter than the surroundings in T2-MRI. The T1-hypointense are areas less dense than the surrounding NAW, and appear black on T1-MRI. They are mainly axonal degeneration areas.
It has also been noted that percentage of children with anti-mog antibodies respect a demyelinating sample is higher than for adults [32] Some NMO patients present double positive for autoantibodies to AQP4 and MOG. These patients have MS-like brain lesions, multifocal spine lesions and retinal and optic nerves atrophy. [33]
Additional MRI findings for absent/unknown AQP4-IgG Optic neuritis: Either 1) brain MRI showing normal findings or only nonspecific white matter lesions, or 2) optic nerve MRI showing T2-hyperintensity, or T1 enhancing lesion, greater than 1/2 optic nerve length or involving optic chiasm Acute myelitis