Terminal zones of myelination: MR evaluation of children aged 20-40 months.

Abstract

The only area that can still exhibit a persistent T2 hyperintensity on MR images at about 2 years of age is considered to be the peritrigonal region: the so-called terminal zone. At this age in our patients, however, a persistent T2 hyperintensity was noted in the frontotemporal subcortical regions. In these areas, the myelination appeared complete at 36-40 months of age. The so-called terminal zones were the subcortical areas rather than the peritrigonal area, and complete myelination took place by about age 3 years.