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Abstract

At 1.5 T reciprocity principle based quantification strategies have been successfully used to quantify brain metabolites. But these methods all rely on the assumption that the magnitude of the RF transmission field B1+ and the reception field B1- are equal at all points in the subject. This is not true at higher field strengths and for example differences in the concentrations measured in the left and right hemisphere are observed when these methods are directly applied at higher fields. Here a further development is presented, proposing a correction for deviations of B1+ from B1- to allow concentration measurements at 3T and even higher field strength without the need of assumptions about concentrations of an internal reference. The obtained metabolite concentrations in vivo in 31 healthy volunteers highly agree with values estimated with internal water referencing, demonstrating the capabilities of this new method, which might make concentration measurements in diseased tissue more reliable.