What are the key radiological and clinical features of Canavan disease, including head size, age of onset, white and gray matter involvement, and biochemical markers?

Canavan disease typically presents with a normal to large head size and onset before 1 year of age. It is characterized by diffuse white matter involvement and vacuolization of cortical gray matter on MRI. The disease results from a deficiency of aspartoacylase, leading to the accumulation of N-acetylaspartate (NAA), detectable as elevated NAA peaks on MR spectroscopy. Key diagnostic features include macrocephaly, hypotonia, and developmental delay. Be cautious of mimickers such as other leukodystrophies; differentiating them relies on specific MRS findings.