title: Separation and quantification of lactate and lipid at 1.3 ppm by diffusion-weighted magnetic resonance spectroscopy.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.|Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Wang
authors.affiliation: Department of Surgery, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors.forename: Gilberto K K
authors.initials: GK
authors.lastname: Leung
authors.affiliation: Department of Surgery, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors.forename: Karrie M Y
authors.initials: KM
authors.lastname: Kiang
authors.affiliation: School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors.forename: Danny
authors.initials: D
authors.lastname: Chan
authors.affiliation: Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.|Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Cao
authors.affiliation: Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.|Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.|State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors.forename: Ed X
authors.initials: EX
authors.lastname: Wu
mesh_terms: D000465:Algorithms; D000818:Animals; D001923:Brain Chemistry; D001932:Brain Neoplasms / Q000737:chemistry*; D045744:Cell Line, Tumor; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D019344:Lactic Acid / Q000032:analysis*; D008055:Lipids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D057054:Molecular Imaging / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D008055:Lipids; D019344:Lactic Acid
keywords: C6 glioma; diffusion weighting; lactate; lipid; magnetic resonance spectroscopy; molecular size; spectral overlapping