Diffusion-tensor imaging derived metrics of the corpus callosum in children with neurofibromatosis type I

MR morphometric studies have suggested that structural brain abnormalities including corpus callosum enlargement may, in part, explain cognitive deficits in children with neurofibromatosis type 1 (NF-1). Diffusion tensor imaging (DTI) metrics of the corpus callosum in adults with NF-1 have recently been reported, but such studies in children with NF-1 are needed. The purpose of this study was to quantify the DTI metrics at 3 T of different regions of the corpus callosum in children with NF-1.

DTI metrics from seven consecutively identified patients with NF-1 (6 boys and 1 girl; age range, 3-17 years; average age, 7.0 years) were compared with 11 age- and sex-matched control subjects (10 boys and one girl; age range, 3-17 years; average age, 7.1 years) at 3 T. Fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were calculated in different sections of the corpus callosum as well as whole-brain mean diffusivity.

Comparing children with NF-1 to control subjects, there were statistically significant decreases in fractional anisotropy in the genu, anterior body, and isthmus of the corpus callosum and significant increases in radial diffusivity in the genu and anterior body. Whole-brain mean diffusivity histograms revealed significant increases in whole-brain mean diffusivity in children with NF-1.

Children with NF-1 have abnormal DTI metrics, particularly in the genu, and elevated whole-brain mean diffusivity. NF-1-related microstructural abnormalities of the corpus callosum are detectable in childhood and likely persist through myelination maturation.