High spatial resolution ²³Na-MRI for ischemic brain injury detection

Area of Science:

• Neuroimaging
• Biomedical Engineering
• Radiology

Background:

• Sodium-23 (23Na) MRI offers unique insights into brain tissue but faces low signal-to-noise ratio (SNR) challenges for high-resolution imaging.
• Detecting early ischemic stroke, particularly in brain lesions, requires advanced imaging techniques with high spatial resolution.

Purpose of the Study:

• To establish a high-resolution 23Na-MRI platform for preclinical imaging of ischemic stroke.
• To evaluate the capability of the developed platform for early detection of brain injury.

Main Methods:

• A 14 T preclinical MRI scanner equipped with a dual-tuned, head-implanted 1H/23Na RF coil was utilized.
• Simultaneous 1H anatomical and diffusion-weighted imaging (DWI), and 23Na-MRI were acquired in a rodent model of ischemic stroke (MCAO).
• Brain-wide 23Na-MRI was performed with 300x300 µm² in-plane resolution within 4 hours post-stroke induction.

Main Results:

• The developed platform achieved high-resolution 23Na-MRI with improved contrast-to-noise ratio (CNR) compared to conventional T2-weighted images.
• Hyperintense 23Na signals were observed in ischemic regions, correlating spatially with reduced apparent diffusion coefficient (ADC) values indicating restricted water in the ischemic core.
• The elevated 23Na signal effectively identified infarct regions, facilitating early detection of ischemic brain injury.

Conclusions:

• Implanted dual-tuned 1H/23Na RF coils enable powerful high-resolution 23Na-MRI acquisition.
• This approach significantly aids in the early detection and characterization of ischemic brain injury.
• High-resolution 23Na-MRI shows promise for improved stroke diagnosis and monitoring.