Inter-Individual Differences in T₁, T₂, and Proton Density Using Quantitative Synthetic Imaging for ¹H-MRS...

Area of Science:

• Biomedical Imaging
• Magnetic Resonance Spectroscopy

Background:

• Proton magnetic resonance spectroscopy (¹H-MRS) quantifies metabolites using water as a reference.
• Accurate quantification relies on tissue-specific water T1, T2 relaxation constants, and proton density (PD).
• Literature values for these parameters can introduce variability due to age and clinical conditions.

Purpose of the Study:

• To assess the agreement between metabolite concentrations calculated using individually measured vs. literature-based water relaxation parameters and proton density.
• To evaluate the feasibility of using rapid multi-dynamic multi-echo (MDME) imaging for acquiring these individual-specific parameters.
• To determine the impact of parameter variability on metabolite concentration calculations.

Main Methods:

• ¹H-MRS and MDME data were acquired from 26 healthy volunteers (18-40 years).
• Metabolite concentrations were calculated using both individually measured and literature-based T1, T2, and PD values.
• Sensitivity analysis was performed to assess the influence of extended parameter ranges.

Main Results:

• MDME successfully provided individual T1, T2, and PD values for tissue correction.
• Metabolite concentrations showed strong agreement between individually measured and literature-based values.
• Individually measured parameters led to slightly lower metabolite concentrations compared to literature values, with T1 relaxation showing the most significant impact on variability.

Conclusions:

• MDME imaging enables fast, individual-specific acquisition of relaxation parameters for accurate ¹H-MRS tissue correction.
• This approach is highly relevant for populations with varying physiological parameters, including pediatric, elderly, and clinically diagnosed individuals.
• The study validates a practical method for improving metabolite quantification in diverse research and clinical settings.