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31 P MRS of myocardial inorganic phosphate using radiofrequency gradient echoes
Author(s) -
Gober J. R.,
Schwartz G. G.,
Schaefer S.,
Massie B. M.,
Matson G. B.,
Weiner M. W.,
Karczmar G. S.
Publication year - 1991
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.1910200202
Subject(s) - phosphocreatine , nuclear magnetic resonance , chemistry , phosphomonoesters , spectral line , nuclear magnetic resonance spectroscopy , intracellular ph , inorganic phosphate , analytical chemistry (journal) , signal (programming language) , intracellular , physics , medicine , chromatography , biochemistry , astronomy , computer science , programming language , enzyme , energy metabolism
Determination of the chemical shift and integral of the myocardial intracellula inorganic phosphate ( P i ) resonance by 31 P magnetic resonance spectroscopy (MRS) is often precluded due to a large overlapping signal from 2,3‐diphosphoglycerate (2,3‐DPG) from chamber and myocardial blood. This report demonstrates the use of radiofrequency (RF) magnetic field gradient echoes (RFGE) to eliminate signals from 2,3‐DPG in flowing blood, while retaining signals from intracellular myocardial P i , ATP, and phosphocreatine (PCr). The ECG‐triggered 31 P spectra were acquired from the myocardium of open chest pigs using a Philips Gyroscan 2‐T magnetic resonance spectrometer. A 2.5‐cm‐diameter surface coil attached to the myocardium was used to provide the RF gradient as well as for excitation and detection of signals. Optimal performance of the RFGE pulse sequence was obtained when the RF gradient pulses were centered at peak diastole or peak systole. Under these conditions, 2, 3‐DPG signals were completely suppressed, and sensitivity was usually sufficient to allow detection of a well‐resolved P i signal. Myocardial pH determined from RFGE experiments was 7.16 ± 0.10, and the ratio of the integrals of the P i and ATP resonances ( P i /ATP) was 0.24. The mean signal‐to‐noise ratio ( S/N ) for PCr in control spectra acquired in 4 min was 19/1, while the mean S/N for PCr in RFGE‐edited spectra acquired in 15 min was 11/1, demonstrating that the present implementation of the RFGE method results in significant loss in sensitivity. These experiments demonstrate that RFGE‐editing allows accurate determination of the chemical shift and integral of the P i resonance in blood‐perfused myocardium in situ . © 1991 Academic Press, Inc.