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Quantification of phosphorus metabolites from chemical shift imaging spectra with corrections for point spread effects and B 1 inhomogeneity
Author(s) -
Murphy Joseph,
Jiang Hong,
Stoyanova Radka,
Brown Truman R.
Publication year - 1998
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.1910390313
Subject(s) - phosphocreatine , spectral line , nuclear magnetic resonance , voxel , chemistry , computational physics , saturation (graph theory) , fast fourier transform , optics , analytical chemistry (journal) , materials science , physics , mathematics , algorithm , computer science , medicine , combinatorics , astronomy , artificial intelligence , chromatography , energy metabolism
A method is described for quantifying phosphorus metabolites in tissue using spectra localized with surface coils and chemical shift imaging (CSI) and assuming that metabolites are uniformly distributed within a well‐defined volume. An analytical expression is developed that yields a single numerical correction factor that takes into account the excitation and receiver profiles of the coil, T 1 saturation, and point spread effects associated with Fourier transformation of CSI data. An external phosphorus standard is used to calibrate instrument gain and the B 1 profile of the coil. For spherical samples, point spread effects can modulate the signal intensities of three‐dimensional CSI spectra from ‐32% to +54%, depending on the voxel size. Measurements of phantoms of known concentrations showed systematic variations of ± 10% and random errors of ± 5%. We have used this method to measure the concentration of phosphocreatine in the thigh muscle of normal volunteers.