Fast three-dimensional sodium imaging of human brain

Area of Science:

• Medical Imaging
• Biophysics
• Neuroscience

Background:

• Sodium (Na+) plays a crucial role in physiological processes, but its in vivo imaging is challenging due to low concentrations and fast relaxation.
• Understanding sodium's behavior in biological tissues is vital for diagnosing and monitoring neurological conditions.

Purpose of the Study:

• To present a novel three-dimensional (3D) sodium imaging technique for in vivo human brain analysis.
• To characterize the in vivo sodium relaxation behavior within the human brain at 2.0 Tesla.

Main Methods:

• A 3D sodium imaging sequence with a minimum echo time (TE) of 0.9 ms was implemented on a 2.0 Tesla whole-body magnetic resonance imaging (MRI) system.
• In vivo sodium relaxation parameters (T2*) were measured in the brain tissue of three healthy volunteers.
• 3D sodium brain images were acquired with a spatial resolution of 4.7 x 4.7 x 10 mm and a voxel volume of 0.2 cc.

Main Results:

• Two distinct T2* relaxation components of sodium in brain tissue were quantified: a fast component (1.2–1.6 ms) and a slow component (7.1–8.4 ms).
• High signal-to-noise ratios (SNR) were achieved: 20 in brain tissue and 30 in cerebrospinal fluid (CSF).
• Acquisition time for 3D sodium brain imaging was efficient, completed in 8.5 minutes.

Conclusions:

• The developed 3D sodium imaging technique enables rapid and high-quality in vivo visualization of sodium in the human brain.
• The quantification of distinct sodium T2* relaxation components provides valuable insights into brain tissue composition and physiology.
• This technique holds potential for advancing the diagnosis and understanding of neurological disorders through sodium MRI.