The macromolecular MR spectrum does not change with healthy aging

Area of Science:

• Neuroimaging
• Biochemistry
• Human Physiology

Background:

• Mobile macromolecules (MMs) are abundant in the brain, but their spectral signals and age-related changes are not fully understood.
• In vivo magnetic resonance spectroscopy (MRS) offers a non-invasive method to study brain metabolites and macromolecules.

Purpose of the Study:

• To acquire mobile macromolecule (MM) spectra from healthy participants using in vivo MRS.
• To investigate potential changes in MM signals related to participant age and sex.

Main Methods:

• 102 healthy volunteers (20-69 years) underwent 3T PRESS MRS in the centrum semiovale (CSO) and posterior cingulate cortex (PCC).
• Osprey software was used to model and subtract metabolite signals, isolating MM spectra.
• Statistical analyses included Pearson's correlation for age, ANOVA for age groups, and t-tests for sex differences.

Main Results:

• MM spectra were successfully acquired in most participants (99/102 in CSO, 96/102 in PCC).
• No significant correlations were found between MM signal integrals and age, nor between MM signals and sex.
• White matter and gray matter fractions decreased with age, while cerebrospinal fluid increased in both CSO and PCC.

Conclusions:

• A pre-defined MM basis function is suitable for linear combination modeling of metabolite data across diverse age and sex groups.
• While MM signals themselves did not change, underlying brain tissue composition (WM, GM, CSF) exhibited age-related alterations.