Noninvasive quantification of human brain ascorbate concentration using 1H NMR spectroscopy at 7 T

Area of Science:

• Neuroimaging
• Biochemistry
• Magnetic Resonance Spectroscopy

Background:

• Ascorbate (vitamin C) plays crucial roles in brain function.
• Noninvasive quantification of brain ascorbate is challenging.
• Previous studies were limited by lower magnetic field strengths.

Purpose of the Study:

• To quantify human brain ascorbate noninvasively at 7 Tesla using two (1)H NMR spectroscopy methods.
• To assess the reliability and efficiency of these methods at higher magnetic fields.

Main Methods:

• Utilized short-echo time STEAM and MEGA-PRESS homonuclear editing (1)H NMR spectroscopy.
• Acquired data from the occipital lobe of eight healthy subjects at 7 Tesla.
• Compared results from both spectroscopy methods.

Main Results:

• Excellent agreement between ascorbate concentrations measured by STEAM and MEGA-PRESS ([Asc] = 1.1 ± 0.3 µmol/g vs. 1.2 ± 0.2 µmol/g).
• Demonstrated reliable quantification of ascorbate alongside 15 other metabolites at 7 T.
• Short-echo time STEAM offered faster acquisition and minimal T(2) relaxation effects.
• MEGA-PRESS at 7 T showed improved signal-to-noise ratio due to enhanced chemical shift dispersion.

Conclusions:

• 7 Tesla (1)H NMR spectroscopy enables reliable and simultaneous noninvasive quantification of brain ascorbate.
• Both STEAM and MEGA-PRESS methods are effective at 7 T, with STEAM offering advantages in speed and relaxation insensitivity.
• This advancement facilitates further research into the role of vitamin C in neurological health and disease.