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[Quantification of brain metabolites by 1H spectroscopy using cyclohexane as an external reference]
Summary
This study validates MR spectroscopy for brain metabolite quantification using cyclohexane as a standard. Results show reliable measurements of choline, creatine, and NAA in healthy individuals and brain cancer patients undergoing radiotherapy.
Area of Science:
- Neuroimaging
- Biophysics
- Medical Physics
Background:
- Magnetic Resonance (MR) spectroscopy is crucial for non-invasively measuring brain metabolites.
- Accurate quantification of metabolites like choline (Cho), creatine/phosphocreatine (Cr/PCr), and N-acetylaspartate (NAA) is essential for clinical applications.
- External standards can improve the reliability of MR spectroscopy quantification.
Purpose of the Study:
- To assess the reliability of quantifying brain metabolite concentrations using MR spectroscopy with a cyclohexane external standard.
- To evaluate the accuracy of choline concentration measurements in a phantom study.
- To measure brain metabolite concentrations in healthy volunteers and brain cancer patients before, during, and after radiotherapy.
Main Methods:
- Proton Magnetic Resonance (MR) spectroscopy with a PRESS sequence was employed.
- A cyclohexane sample served as an external standard for signal intensity ratio measurements.
- Geometrical arrangements and coil loading factors were varied to test measurement stability.
- Choline (Cho) concentrations were calculated and compared to known values.
- Brain metabolites (Cho, Cr/PCr, NAA) were quantified in vivo in human subjects.
Main Results:
- Variation in the water to cyclohexane spectrum intensity ratio was consistently below 1.5%.
- Phantom studies demonstrated a low error (0.05 +/- 0.10 mmol/L) in choline quantification.
- In vivo measurements yielded metabolite concentrations: Cho 1.6 +/- 0.4 mmol/L, Cr/PCr 6.4 +/- 1.1 mmol/L, NAA 8.2 +/- 0.1 mmol/L.
- No significant differences (p > 0.05) in metabolite concentrations were observed across study groups and radiotherapy stages.
Conclusions:
- MR spectroscopy, utilizing cyclohexane as an external standard, provides a reliable method for quantifying brain metabolite concentrations.
- The technique demonstrates high accuracy and stability across various experimental conditions.
- In vivo metabolite levels remain stable in healthy individuals and brain cancer patients throughout radiotherapy, suggesting robustness of the method and biological stability.