Compensation of Offresonance Magnetization Transfer Artifact in SPECIAL at 7T

Alexander Fuchs¹, Anke Henning¹, David Brunner¹, Peter Boesiger¹

The SPECIAL sequence is a 2 step ISIS like localization scheme that allows to measure 3D SV spectra at very short echo times. This is especially interesting for spectroscopy at ultra-high fields were metabolite relaxation complicates the detection of certain metabolites. It is demonstrated in this work that in SPECIAL without outer volume suppression the ISIS inversion pulse induces magnetization transfer effects between bound protons and skull lipids. This can lead to strong outer volume fat contamination of the actual spectrum. Furthermore a modification to the SPECIAL sequence is proposed to overcome these types of artifacts.