Deuterium brain imaging at 7T during D₂ O dosing.

Area of Science:

• Magnetic Resonance Imaging
• Neuroimaging
• Biophysics

Background:

• Magnetic Resonance Imaging (MRI) is a powerful tool for non-invasive brain analysis.
• Deuterium (² H) labeling allows tracking of water dynamics in vivo.
• High-field MRI (7 Tesla) offers enhanced sensitivity for detecting low-concentration isotopes.

Purpose of the Study:

• To characterize the deuterium (² H) MR signal in the human brain at 7T.
• To monitor brain ² H enrichment during deuterated water (D₂ O) loading.
• To measure deuterium T₁ and T₂ ^* relaxation times in different brain tissues.

Main Methods:

• ² H spectroscopy and imaging were employed to track enrichment over time.
• Multi-echo gradient echo (MEGE) imaging was used to map ² H T₁ and T₂ ^* relaxation times.
• Co-registration with ¹ H images enabled relaxation time estimation in CSF, GM, and WM.

Main Results:

• ² H concentrations correlated with D₂ O dose and body mass.
• Brain ² H signal changes showed similar time-courses across regions.
• Gradient echo images achieved ˜16 SNR with 0.36 ml voxel volume in 7.5 minutes.
• Deuterium T₁ values were shorter than ¹ H; T₂ ^* values were similar.
• ² H relaxation times were longer in CSF compared to GM and WM.

Conclusions:

• Deuterium MRI at 7T successfully tracked brain ² H concentration increases during D₂ O loading.
• The study reports novel ² H T₁ and T₂ ^* relaxation times for water in human brain tissues (GM, WM, CSF).
• These findings provide valuable parameters for future deuterium MRI studies of brain water metabolism and dynamics.