Skin sodium measured with ²³Na MRI at 7.0 T.

Area of Science:

• Medical Imaging
• Biophysics
• Human Physiology

Background:

• Skin sodium storage is a vital regulator of blood pressure and volume.
• Recent advancements in (23) Na MRI at 3.0 Tesla have enabled human skin sodium assessment.
• Further improvements in spatial resolution are needed for detailed investigation.

Purpose of the Study:

• To evaluate the feasibility of high in-plane spatial resolution (23) Na MRI in human skin at 7.0 Tesla.
• To assess the sensitivity and safety of a novel 7.0 T RF coil array for skin MRI.
• To investigate the age-dependent changes in skin sodium content.

Main Methods:

• Development and testing of a two-channel transceiver RF coil array for 7.0 T skin MRI.
• Specific absorption rate (SAR) simulations and RF power deposition assessments for safety.
• In vivo (23) Na MRI using 2D gradient echo imaging in 17 adult volunteers at 0.9 × 0.9 mm(2) in-plane resolution.

Main Results:

• The 7.0 T (23) Na RF coil demonstrated improved sensitivity for superficial skin imaging.
• Intra-subject variability in skin sodium content was low (<10.3%).
• A significant age-dependent increase in skin sodium content was observed (r = 0.78).

Conclusions:

• High in-plane spatial resolution (23) Na MRI at 7.0 T is feasible for human skin.
• This technique offers enhanced potential for studying sodium balance and storage in basic research and clinical applications.
• Improved 7.0 T MRI may advance understanding of sodium's role in physiological regulation.