The role of the N-acetylaspartate multiplet in the quantification of brainmetabolites

N-Acetylaspartate, whose methyl singlet is the primary magnetic resonance m arker of neuronal dysfunction, also gives rise to a sequence-dependent, str ongly coupled multiplet that overlaps the resonances of several other metab olites. Results are presented in this paper of a full numerical calculation of the response of the strongly coupled aspartate multiplet of N-acetylasp artate to a PRESS pulse sequence employing practical slice-selective pulses . These calculations, confirmed by experiments on phantoms, demonstrate the ability to predict the dependence of the response of strongly coupled spin s on pulse design, as well as on interpulse evolutions, thereby facilitatin g a more rigorous comparison of the use of spectral fitting routines employ ed to extract metabolite concentrations on different instruments.