7T head volume coils: improvements for rostral brain imaging

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering
• Neuroimaging

Background:

• 7T head coils exhibit inhomogeneous radiofrequency (RF) magnetic fields due to RF field/tissue interactions.
• This leads to reduced sensitivity in peripheral and rostral brain regions compared to the center.

Purpose of the Study:

• To enhance the performance and homogeneity of 7T head coils in rostral brain regions.
• To address the limitations of current coil designs in achieving uniform RF field distribution.

Main Methods:

• Construction and testing of two head-sized quadrature volume coils with different lengths (17 cm and 10 cm) at 7T.
• Evaluation of coil performance using a Varian Inova system.

Main Results:

• A shorter volume head coil improved coil efficiency by 20% in the rostral head regions.
• Homogeneity improved, with a 10%-20% variation in axial slices near the top of the head.
• Increased peripheral B(1) values contributed to improved homogeneity.

Conclusions:

• A less deeply positioned head or a shorter volume coil significantly enhances performance and homogeneity for rostral head imaging at ultrahigh fields (7T+).
• This coil configuration is effective for neuroimaging studies targeting superior brain regions.