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.
Keywords