Imaging Human Brain Perfusion with Inhaled Hyperpolarized ¹²⁹Xe MR Imaging

Area of Science:

• Medical Imaging
• Neuroscience
• Biophysics

Background:

• Assessing human brain tissue perfusion is crucial for diagnosing neurological conditions.
• Current Magnetic Resonance (MR) imaging methods for perfusion assessment often require contrast agent injections.
• Developing non-invasive and sensitive perfusion imaging techniques remains a significant challenge.

Purpose of the Study:

• To evaluate the feasibility of directly imaging human brain tissue perfusion using inhaled hyperpolarized 129-xenon (129Xe) MR imaging.
• To assess the sensitivity and structural correlation of 129Xe perfusion imaging compared to conventional methods.

Main Methods:

• In vivo MR imaging was performed in three healthy participants using inhaled hyperpolarized 129Xe.
• A high-yield 129Xe polarizer, custom radiofrequency coils, and optimized gradient-echo protocols were employed.
• Conventional T1-weighted proton (1H) and arterial spin labeling (ASL) perfusion images were acquired for comparison.

Main Results:

• Direct imaging of 129Xe uptake in the brain was achieved with a signal-to-noise ratio of 31 ± 9.
• The 129Xe uptake distribution showed structural similarities to gray matter on 1H images and ASL perfusion maps.
• The method successfully imaged xenon gas uptake in the extravascular brain tissue compartment.

Conclusions:

• Hyperpolarized 129Xe MR imaging provides an injection-free method for imaging cerebral tissue perfusion.
• This technique visualizes inhaled xenon gas uptake across the intact blood-brain barrier.
• The achieved sensitivity surpasses that of contemporary MR imaging methods for direct perfusion visualization.