Joonas Arttu Autio1,2, Tao Jin3,
S-G Kim3,4, Takayuki Obata1
1Department of Biophysics, National
Institute of Radiological Sciences, Chiba, Japan; 2Department of
Neurobiology, University of Kuopio, Kuopio, Finland; 3Department
of Radiology, University of Pittsburgh, Pittsburgh, PA, United States; 4Department
of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
Previous
study has demonstrated an indirect MRI detection of hydroxyl protons of small
metabolites via chemical exchange saturation transfer. We used an
on-resonance spin-locking (SL) pulse to detect proton exchange for hydroxyl-,
amide- and amine-phantoms, and a protein sample. Analysis of spin-lattice
relaxation rate in the rotating frame dispersion over a range of SL B1
fields, resulted in robust estimates for intermediate proton exchange rates
and exchangeble proton site populations. Our results suggest that SL
technique with on-resonance irradiation is not sensitive to very slow
exchange, but may be more suited for quantitative study in the intermediate
exchange regime.
Keywords