Brain metabolite proton T2 mapping at 3.0 T in relapsing-remitting multiple sclerosis

Area of Science:

• Neuroimaging
• Biochemistry
• Medical Physics

Background:

• Multiple Sclerosis (MS) involves white matter (WM) and gray matter (GM) lesions.
• Accurate metabolic quantification in MS is crucial for understanding disease progression and treatment efficacy.
• Proton spectroscopy imaging (PSI) is a key technique for in vivo metabolite assessment.

Purpose of the Study:

• To investigate whether T2 signal variations in MS brain lesions and normal-appearing tissue are similar.
• To determine if observed signal variations accurately represent true metabolite concentration differences.
• To test the hypothesis that T2 signal characteristics are consistent across different brain regions and lesion types in MS.

Main Methods:

• Multivoxel point-resolved proton spectroscopy imaging (PSI) was performed at 3.0 T in 10 relapsing-remitting (RR) MS patients.
• T2 distributions of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) were mapped in brain regions and lesions.
• Statistical analyses, including mixed-model ANOVA and Wilcoxon tests, compared T2 values across regions, lesion types, and with healthy controls.

Main Results:

• Mean T2 values for NAA, Cr, and Cho were similar in peak position across all voxels.
• Regional T2 values were significantly longer in WM than GM but not significantly different from isointense or hypointense MS lesions.
• T2 values in MS patients were shorter compared to healthy controls, with varying percentages for each metabolite in GM and WM.

Conclusions:

• Average T2 values per metabolite are sufficient for metabolic quantification in any brain region and lesion in RR MS patients at 3.0 T with short echo times.
• Disease duration, age, or disability do not significantly impact the utility of average T2 values for metabolite quantification in MS.
• These findings simplify metabolic quantification protocols in MS research and clinical practice.