Multi-echo T2 imaging (ME-T2) enables the investigation of multiple white matter compartments. The short T2 compartment has been the focus of recent investigations due to its specificity for the myelin water compartment. However, the much larger intra/extra cellular (IE) compartment has been relatively less explored. Here we investigate age differences in the geometric mean T2 (geomT2IEW) of the IE compartment in subcortical white matter tracts. We demonstrate that the effects of age on geomT2IEW are not uniform across white matter tracts and suggest that this index may offer additional value in the characterization of age differences of white matter microstructure.