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The term "leukoaraiosis" was coined in 1986 [6] [7] by Hachinski, Potter, and Merskey as a descriptive term for rarefaction ("araiosis") of the white matter, showing up as decreased density on CT and increased signal intensity on T2/FLAIR sequences (white matter hyperintensities) performed as part of MRI brain scans. These white matter changes ...
Hyperintensities are commonly divided into 3 types depending on the region of the brain where they are found. Deep white matter hyperintensities occur deep within white matter, periventricular white matter hyperintensities occur adjacent to the lateral ventricles and subcortical hyperintensities occur in the basal ganglia. [citation needed]
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 ]
Mild Moderate Severe ARIA-E Edema: FLAIR hyperintensity confined to sulcus and/or cortex/subcortical white matter in one location < 5 cm FLAIR hyperintensity 5 to 10 cm, or more than 1 site of involvement, each measuring < 10 cm FLAIR hyperintensity measuring > 10 cm, often with significant subcortical white matter and/or sulcal involvement.
The diagnosis is typically made with magnetic resonance imaging of the brain. The findings most characteristic for PRES are symmetrical hyperintensities on T 2-weighed imaging in the parietal and occipital lobes; this pattern is present in more than half of all cases. [1] [3] FLAIR sequences can be better at showing these abnormalities. [4]
Lesions typically are found in the white matter of brains injured by DAI; these lesions vary in size from about 1–15 mm and are distributed in a characteristic pattern. [9] DAI most commonly affects white matter in areas including the brain stem, the corpus callosum, and the cerebral hemispheres.
The MRI of patients with VWM shows a well defined leukodystrophy. These MRIs display reversal of signal intensity of the white matter in the brain. Recovery sequences and holes in the white matter are also visible. [4] Over time, the MRI is excellent at showing rarefaction and cystic degeneration of the white matter as it is replaced by fluid.
White matter is composed of bundles, which connect various grey matter areas (the locations of nerve cell bodies) of the brain to each other, and carry nerve impulses between neurons. Myelin acts as an insulator, which allows electrical signals to jump , rather than coursing through the axon, increasing the speed of transmission of all nerve ...