<p>Table e-1. Special MRI characteristics</p><p>1. Cystic white matter degeneration Childhood ataxia and central hypomyelination / vanishing white matter (CACH/VWM) Mitochondrial defects Alexander disease Neonatal energy depletion (inborn error or exogenous), including hypoglycemia Infections, especially in the neonatal period Incontinentia pigmenti</p><p>2. Anterior temporal cysts Megalencephalic leukoencephalopathy with subcortical cysts (MLC) Leukoencephalopathy with anterior temporal cysts without megalencephaly Merosin deficient congenital muscular dystrophy (inconstant) Aicardi-Goutières syndrome (inconstant) Congenital cytomegalovirus infection</p><p>3. Megalencephalic leukoencephalopathies Alexander disease Megalencephalic leukoencephalopathy with subcortical cysts (MLC) Canavan disease Infantile lysosomal storage disorders (inconstant) L-2-hydroxyglutaric aciduria (inconstant)</p><p>4. Enlarged perivascular spaces or small cysts Mucopolysaccharidoses Chromosomal or genetic mosaicism Other chromosomal abnormalities Lowe syndrome</p><p>5. Additional gray matter lesions Cortical dysplasia Zellweger syndrome Other early onset peroxisomal disorders Congenital muscular dystrophies Congenital cytomegalovirus infection</p><p>Cortical lesions Mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS) Alpers disease (POLG1 mutations) Urea cycle defects Multiple sclerosis (MS), acute disseminated encephalomyelitis (ADEM) Basal ganglia lesions Mitochondrial defects Wilson disease Alexander disease Sulfite oxidase deficiency / molybdenum cofactor deficiency Canavan disease L-2-hydroxyglutaric aciduria Other amino acidopathies and organic acidurias GM1 and GM2 gangliosidoses Fucosidosis Leukoencephalopathy with calcifications and cysts (LCC) Hypomyelination with atrophy of the basal ganglia and cerebellum (HABC) Dentatorubropallidoluysian atrophy (DRPLA) Vasculopathies (see microbleeds)</p><p>6. Contrast enhancement Infectious disorders Multiple sclerosis (MS), acute disseminated encephalomyelitis (ADEM) Vasculitis Vascular/perivascular malignancies Hemophagocytic lymphohistiocytosis Alexander disease Mitochondrial disorders Cerebral X-linked adrenoleukodystrophy (X-ALD) Leukoencephalopathy with calcifications and cysts (LCC)</p><p>7. Calcium deposits Congenital cytomegalovirus infection Congenital toxoplasmosis Congenital human immunodeficiency virus (HIV) encephalopathy Perinatal hypoxic-ischemic brain damage Phenylketonuria (PKU) variants Aicardi-Goutières syndrome Cockayne syndrome Leukoencephalopathy with calcifications and cysts Vasculopathies (see microbleeds)</p><p>8. Micro-bleeds Arterio(lo)sclerosis Amyloid angiopathy Collagen IV A1 defect Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) Vasculitis 9. Spinal cord involvement Multiple sclerosis (MS) Neuromyelitis optica (NMO) Acute disseminated encephalomyelitis (ADEM) Brucellosis Alexander disease Leukoencephalopathy with brain stem and spinal cord involvement and elevated lactate (LBSL) Mitochondrial defects Vacuolar myelopathy related to human immunodeficiency virus (HIV) infection Vitamin B12 deficiency and defects in its metabolism</p><p>10. Evolution over time Stable Congenital infections Chromosomal abnormalities, including mosaicism Acquired damage Relapsing-remitting Multiple sclerosis Vasculitis Some infections Progressive Almost all genetic leukoencephalopathies</p>