Quantifying global-brain metabolite level changes with whole-head proton MR spectroscopy at 3T

Area of Science:

• Neuroimaging
• Biomarkers
• Metabolomics

Background:

• ¹H-MRS is used to measure brain metabolites (NAA, Glx, Cr, Cho) as markers for neurological conditions.
• Assessing serial changes in these metabolites is crucial for understanding disease progression and treatment response.
• Non-localized, whole-head ¹H-MRS offers broader spatial coverage compared to localized techniques.

Purpose of the Study:

• To evaluate the sensitivity of non-localized, whole-head ¹H-MRS to detect individual serial changes in key brain metabolites.
• To determine the repeatability and reliability of metabolite measurements using this technique for longitudinal studies.

Main Methods:

• Prospective study involving 18 healthy young volunteers (9 women, 9 men).
• Performed four back-to-back and three serial non-localizing ¹H-MRS scans (~3 min each).
• Analyzed data using within-subject coefficient of variation (CV) to assess intra- and inter-scan repeatability.

Main Results:

• Intra-scan CVs for NAA, Glx, Cr, and Cho were 3.9±1.8%, 7.3±4.6%, 4.0±3.4%, and 2.5±1.6%, respectively.
• Inter-scan (longitudinal) CVs were 7.0±3.1%, 10.6±5.6%, 7.6±3.5%, and 7.0±3.9% for NAA, Glx, Cr, and Cho.
• The method demonstrated 80% power to detect changes of 14-27% between serial measurements.

Conclusions:

• Non-localized whole-head ¹H-MRS is sensitive to individual serial changes in brain metabolites (NAA, Glx, Cr, Cho).
• This approach can add specificity to the assessment of total disease load in neurological disorders.
• It facilitates monitoring of diffuse pathologies with improved speed, spatial coverage (~90% brain), and sensitivity compared to localized ¹H-MRS.