MR spectroscopy using multi-ring surface coils

Area of Science:

• Magnetic Resonance Imaging and Spectroscopy
• Radiofrequency Coil Design

Background:

• Spatially uniform B(1)-fields are crucial for accurate MR imaging and spectroscopy.
• Volume coils are not always available or suitable for all applications, leading to challenges in quantitative MRS due to non-uniform coil responses.
• Standard single-loop surface coils offer high signal-to-noise ratio (SNR) but suffer from poor B(1) field homogeneity.

Purpose of the Study:

• To introduce and evaluate novel multi-ring surface coils designed to produce a locally uniform B(1) field.
• To assess the performance of these coils in MR spectroscopy compared to traditional volume and surface coils.
• To determine if these coils can overcome the limitations of existing coil technologies for quantitative MRS.

Main Methods:

• Development of two and three-ring surface coil designs.
• MR spectroscopy experiments were conducted using the proposed multi-ring coils.
• Comparison of spatial localization, RF power requirements, SNR, water suppression, and specific absorption rate (SAR) against standard volume and single-loop surface coils.

Main Results:

• The multi-ring coils produced a locally uniform B(1) field, comparable in sensitivity and power requirements to standard surface coils.
• MR spectroscopy with multi-ring coils achieved spatial localization similar to volume coils.
• Compared to standard surface coils, multi-ring coils demonstrated improved water suppression, localization, and reduced outer voxel contamination, with only a minor SNR loss and moderate SAR increase.

Conclusions:

• Multi-ring surface coils represent a hybrid technology, bridging the gap between volume and standard surface coils.
• These coils offer a practical solution for applications requiring a uniform B(1) field when volume coils are not feasible.
• The proposed coils enhance quantitative MRS by providing improved B(1) homogeneity and localization characteristics.