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Separation and quantification of lactate and lipid at 1.3 ppm by diffusion‐weighted magnetic resonance spectroscopy
Author(s) -
Wang Anna M.,
Leung Gilberto K.K.,
Kiang Karrie M.Y.,
Chan Danny,
Cao Peng,
Wu Ed X.
Publication year - 2017
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.26144
Subject(s) - nuclear magnetic resonance , chemistry , intravoxel incoherent motion , diffusion , nuclear magnetic resonance spectroscopy , analytical chemistry (journal) , spectroscopy , thermal diffusivity , subtraction , in vivo magnetic resonance spectroscopy , diffusion mri , magnetic resonance imaging , chromatography , physics , mathematics , radiology , thermodynamics , medicine , arithmetic , quantum mechanics
Purpose To separate the spectrally overlapped lactate and lipid signals at 1.3 ppm using diffusion‐weighted magnetic resonance spectroscopy (DW‐MRS) based on their large diffusivity difference. Methods DW‐MRS was applied to the gel phantoms containing lactate and lipid droplets, and to the rat brain tumors. Lactate and lipid signals and their apparent diffusion coefficients were computed from the diffusion‐weighted proton spectra. Biexponential fitting and direct spectral subtraction approaches were employed and compared. Results DW‐MRS could effectively separate lactate and lipid signals both in phantoms and rat brain C6 glioma by biexponential fitting. In phantoms, lactate and lipid signals highly correlated with the known lactate concentration and lipid volume fractions. In C6 glioma, both lactate and lipid signals were detected, and the lipid signal was an order of magnitude higher than lactate signal. The spectral subtraction approach using three diffusion weightings also allowed the separation of lactate and lipid signals, yielding results comparable to those by the biexponential fitting approach. Conclusion DW‐MRS presents a new approach to separate and quantify spectrally overlapped molecules and/or macromolecules, such as lactate and lipid, by using the diffusivity difference associated with their different sizes or mobility within tissue microstructure. Magn Reson Med 77:480–489, 2017. © 2016 International Society for Magnetic Resonance in Medicine