We describe a standard set of quantity names and symbols related to the estimation of kinetic parameters from dynamic contrast-enhanced T 1 -weighted magnetic resonance imaging data, using diffusable agents such as gadopentetate dimeglumine (Gd-DTPA). These include a) the volume transfer constant K trans (min ؊1 ); b) the volume of extravascular extracellular space (EES) per unit volume of tissue v e (0 F v e F 1); and c) the flux rate constant between EES and plasma k ep (min ؊1 ). The rate constant is the ratio of the transfer constant to the EES (k ep ‫؍‬ K trans / v e ). Under flow-limited conditions K trans equals the blood plasma flow per unit volume of tissue; under permeability-limited conditions K trans equals the permeability surface area product per unit volume of tissue. We relate these quantities to previously published work from our groups; our future publications will refer to these standardized terms, and we propose that these be adopted as international standards.

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The present results suggest that, at least for some cognitive functions, deficient development and/or loss of NAWM after CRT may provide a neuroanatomical substrate for the adverse impact of a young age at the time of CRT.