Magnetic resonance imaging in leukodystrophies: characteristic patterns and diagnostic relevance.

BACKGROUND

Leukodystrophies are inherited disorders that primarily affect the central nervous system white matter and often present with nonspecific symptoms, making early diagnosis difficult. Magnetic resonance imaging (MRI) is the key initial imaging test because it reveals characteristic myelin patterns that can guide biochemical and genetic workups.

OBJECTIVE

To review clinically useful MRI and MR spectroscopy (MRS) patterns in major leukodystrophies and emphasize their diagnostic relevance using a practical, pattern-recognition approach.

METHODS

Narrative review of the literature integrating conventional MRI, including T1/T2 fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted imaging (DWI), as well as advanced techniques (MRS), with a pictorial, case-based approach.

RESULTS

The pivotal imaging distinction is between hypomyelination-diffuse, persistent T2/FLAIR hyperintensity with relative temporal stability and absent enhancement-and demyelination, characterized by confluent, progressive lesions with disorder-specific topographic predilection. Recognizable signatures include U-fiber sparing and a tigroid pattern in metachromatic leukodystrophy (MLD); parieto-occipital predominance with trizonal enhancement and restricted diffusion in X-linked adrenoleukodystrophy (X-ALD); frontal predominance and the "tadpole sign" in Alexander's disease; optic pathway and thalamic involvement in Krabbe's disease; markedly elevated N-acetylaspartate (NAA) on MRS in Canavan's disease; and tract-selective leukoencephalopathy brainstem/spinal cord involvement with a lactate peak (LBSL). These imaging clues refine differential diagnosis, guide targeted genetic testing, and support longitudinal monitoring.

CONCLUSION

The use of MRI-especially when complemented by DWI and MRS-remains central for early recognition and classification of leukodystrophies. A structured, pattern-based approach integrating clinical context with imaging topography can reduce diagnostic delay and support timely management.