Magnetic resonance imaging pattern recognition in hypomyelinating disorders

Abstract

Hypomyelination is observed in the context of a growing number of genetic disorders that share clinical characteristics. The aim of this study was to determine the possible role of magnetic resonance imaging pattern recognition in distinguishing different hypomyelinating disorders, which would facilitate the diagnostic process. Only patients with hypomyelination of known cause were included in this retrospective study. A total of 112 patients with Pelizaeus-Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, Pelizaeus-Merzbacher-like disease, infantile GM1 and GM2 gangliosidosis, Salla disease and fucosidosis were included. The brain scans were rated using a standard scoring list; the raters were blinded to the diagnoses. Grouping of the patients was based on cluster analysis. Ten clusters of patients with similar magnetic resonance imaging abnormalities were identified. The most important discriminating items were early cerebellar atrophy, homogeneity of the white matter signal on T(2)-weighted images, abnormal signal intensity of the basal ganglia, signal abnormalities in the pons and additional T(2) lesions in the deep white matter. Eight clusters each represented mainly a single disorder (i.e. Pelizaeus-Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, infantile GM1 and GM2 gangliosidosis, Pelizaeus-Merzbacher-like disease and fucosidosis); only two clusters contained multiple diseases. Pelizaeus-Merzbacher-like disease was divided between two clusters and Salla disease did not cluster at all. This study shows that it is possible to separate patients with hypomyelination disorders of known cause in clusters based on magnetic resonance imaging abnormalities alone. In most cases of Pelizaeus-Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, Pelizaeus-Merzbacher-like disease, infantile GM1 and GM2 gangliosidosis and fucosidosis, the imaging pattern gives clues for the diagnosis.

Figure 1

MRI of a 6-year-old male with 4H syndrome. The sagittal T₁-weighted image shows cerebellar atrophy (A). The axial T₂-weighted image (B) shows relatively lower signal of the anterolateral part of the thalamus (white arrow), pyramidal tract at the level of the posterior limb of the internal capsule (black arrow) and the optic radiation (white open arrow).

Figure 2

The axial T₂-weighted image in a 1-year-old male with PMD shows a strikingly homogeneous T₂ signal intensity of the cerebral white matter (A) as compared to a 5-year-old male with 4H syndrome (B).

Figure 3

Axial T₂-weighted images of two male patients with PMLD (age 39 years in A, age 6 years in B) at the level of the pons show T₂ hyperintensity, either in the pyramidal tracts alone (white arrow, A) or in the entire pons (black arrow, B).

Figure 4

Axial T₂-weighted images of a 1-year-old female with fucosidosis demonstrate pronounced T₂ hypointensity of the globus pallidus (white open arrow, A) and substantia nigra (white arrow, B). The optic radiation has a lower signal than the adjacent white matter (black arrow, A).

Figure 5

Axial T₂-weighted images of a 1-year-old female with GM2 gangliosidosis display hypointensity of the corpus callosum (white arrow, A) and T₂ hyperintensity of the basal ganglia (black arrow, B).

Figure 6

MRI of a 3-year-old male with HCC. The axial T₂-weighted image shows prominent T₂ hyperintensity (black arrow, A) and the sagittal T₁-weighted image displays T₁ hypointensity (white arrow, B) of the periventricular and deep white matter.

Figure 7

The axial T₂-weighted image of a 16-year-old male with Salla disease demonstrates hyperintensity of the subcortical white matter, characteristic of patients in Clusters 7 and 8 (A), as compared to more diffuse hyperintensity of the cerebral white matter in a 19-year-old female with hypomyelination (B).

Figure 8

Flow chart developed for reviewing MRI scans displaying signs of hypomyelination. WM = white matter.