d. Alexander disease(Ref: Nelson's 20/e p 713-714;Radiopaedia.org; Caffey's 12e/p337)Name of diseaseMRI Brain findingAlexander diseaseT2 hyperintensities in frontal white matter; shows contrast enhancement;Canavan diseaseMacrocephaly; bilateral symmetric T2 white matter hyperintensity diffusely throughout cerebral white matter; does not enhance at CT & MRI; Large N acetyl aspartate (NAA) peak on MRSAdrenoleukodystrophySymmetrical cerebral white matter signal change involving posterior (occipitoparietal) periventricular white matterKrabbe's diseaseCT: Hyperdense areas symmetrically involving thalami, caudate nuclei (basal ganglia), cerebellum, posterior limbs of internal capsule and brainstem.MRI: 2 patterns; (i) A patchy hyperintense periventricular signal with thalamic involvement onT2-weighted images, consistent with hypomyelination, (ii) patchy low signal on T2-weighted images in a similar distribution to the hyperdense regions seen on CT, which is suspected to represent a paramagnetic effect from calcium deposition in the region.