Meeting Banner
Abstract #0316

MR Spectroscopy Without Water Suppression for the Determination of Proton Exchange Rates in the Human Brain

Erin Leigh MacMillan1, Daniel Guo Quae Chong1, Wolfgang Dreher2, Anke Henning3, Chris Boesch1, Roland Kreis1

1Department of Clinical Research, University of Bern, Bern, Switzerland; 2Dept. Chemistry, University of Bremen, Bremen, Germany; 3Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland

MRS without water suppression can detect exchangeable proton resonances, particularly downfield of water. Employing a two-acquisition scheme with alternating up- or down-field metabolite inversion prior to PRESS, both the metabolite and water spectra were obtained from the human brain in-vivo. The experiment was performed with and without a water inversion prepulse with varying inversion times (TI). The magnetization transfer curves were fit with a Bloch-McConnell two-site exchange model to determine exchange rates, with initial estimates yeilding lifetimes (1/Kmw) ranging from 90ms to >2s, which offer information about pH and chemical microenvironments, and may aid in the understanding of CEST effects.