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Detection of 17 O‐tagged phosphate by 31 P MRS: A method with potential for in vivo studies of phosphorus metabolism
Author(s) -
Thelwall Peter E.
Publication year - 2007
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21226
Subject(s) - phosphate , chemistry , in vivo , phosphorus 31 nmr spectroscopy , nuclear magnetic resonance spectroscopy , phosphorus , nuclear magnetic resonance , radiochemistry , biochemistry , stereochemistry , biology , physics , microbiology and biotechnology , organic chemistry
We present a method for MR detection of 17 O‐labeled phosphate groups. The method employs the T 2 relaxivity effect of 17 O on 31 P nuclei to distinguish between 17 O‐labeled and unlabeled phosphate groups, and uses spin‐echo (SE) acquisitions with RF decoupling at the 17 O frequency to generate 31 P spectra that show only 17 O‐labeled phosphate groups. The method provides an alternative to spin‐labeling experiments, which are limited to the study of rapidly exchanging phosphate groups by the T 1 relaxation rates of phosphorus nuclei. We demonstrate separation of MR signals from labeled and unlabeled phosphate‐containing compounds, and characterization of the T 2 effect of 17 O on phosphate nuclei in 17 O‐labeled phosphate groups. Previous 17 O and 18 O phosphate‐labeled studies used mass spectrometry or high‐resolution MR spectroscopy (MRS) to detect the presence of an isotopic label, which requires ex vivo sample preparation. In our method the detection of 17 O‐labeled phosphate is manifested as a large change in 31 P T 2 , and thus allows in vivo detection using simple MR methods. Thus this method may have potential for in vivo studies of bioenergetics and the metabolism of phosphate‐containing compounds. Magn Reson Med 57:1168–1172, 2007. © 2007 Wiley‐Liss, Inc.