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Improvement of the rotating frame experiment by detection of residual z magnetization: a 31 P MRS study of metabolite levels in a meth‐a sarcoma
Author(s) -
Karczmar G. S.,
Shine N.,
Lawry T. J.,
Weiner M. W.,
Matson G. B.
Publication year - 1989
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1940010402
Subject(s) - metabolite , spectral line , nuclear magnetic resonance , magnetization , residual , physics , materials science , magnetic field , chemistry , analytical chemistry (journal) , computational physics , mathematics , chromatography , algorithm , biochemistry , quantum mechanics , astronomy
The radio frequency field (B 1 ) gradient of a surface coil can be used to obtain spectra from a series of sample regions which experience different B 1 field strengths. We previously reported that the sensitivity of this method, known as the surface coil rotating frame experiment (SCRFE), can be enhanced by applying a composite pulse immediately after signal acquisition to sample residual Z magnetization which is normally undetected. Initially this modified SCRFE was used to obtain spatially resolved spectra across a B 1 gradient of a factor of 2.5. Here we demonstrate the extension of this method to map phosphorylated metabolites across a B 1 gradient of a factor of close to 5. Computer simulations were used to evaluate the performance of the composite pulse, and to assist in analyzing the data. The method was used to obtain 31 P spectra in vivo from various tissue layers within and beneath a murine Meth‐A tumor. The spectra differentiated between metabolite levels in tumor tissue and underlying skeletal muscle. Metabolic heterogeneity within the tumor itself was also evident.