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Quantitative spectroscopic imaging of the human brain
J W Pan1, D B Twieg, H P Hetherington
1Department of Neurology, Center for Nuclear Imaging Research, University of Alabama, Birmingham, USA.
Magnetic Resonance in Medicine
|September 4, 1998
Summary
This study introduces a new method for quantitative brain spectroscopy using B1 correction and cerebrospinal fluid (CSF) referencing. This technique accurately measures brain metabolites like NAA and Cr, showing potential for diagnosing conditions such as multiple sclerosis.
Area of Science:
- Neuroimaging
- Magnetic Resonance Spectroscopy
- Quantitative MRI
Background:
- Accurate metabolite quantification in brain Magnetic Resonance Spectroscopy (MRS) is crucial for diagnosing neurological disorders.
- Existing MRS methods often face challenges with B1 field inhomogeneity and require reliable referencing for quantitative accuracy.
- Cerebrospinal fluid (CSF) offers a potential reference but requires correction for its own B1 field dependence.
Purpose of the Study:
- To develop and validate a novel method for B1 correction and CSF referencing in spectroscopic imaging of the human brain.
- To enable accurate in vivo quantification of brain metabolites including N-acetylaspartate (NAA), creatine (Cr), and choline (Ch).
- To assess the utility of this quantitative method in healthy controls and a patient with secondary progressive multiple sclerosis (MS).
Main Methods:
- Developed a method for rapid, spatially dependent B1 field mapping using a volume head coil at 4.1 T.
- Acquired reference spectra from CSF in the lateral ventricles using Point-Resolved Echo Spectroscopy (PRESS) acquisition.
- Applied B1, T1, and T2 corrections to both the brain spectra and the CSF reference for quantitative analysis.
Main Results:
- The B1 mapping allowed for effective compensation of B1 sensitivity variations in the spectroscopic sequence.
- Quantitative metabolite concentrations (NAA, Cr, Ch) obtained in seven normal controls were in good agreement with literature values.
- Application in a patient with secondary progressive MS revealed distinct abnormalities in NAA and Cr metabolite levels.
Conclusions:
- The developed method provides accurate quantitative brain metabolite measurements by effectively correcting for B1 inhomogeneity and using CSF as a reference.
- This approach enhances the reliability of in vivo MRS for clinical applications.
- The findings demonstrate the potential of this quantitative MRS technique for detecting metabolic alterations in neurological diseases like MS.