Spiral Gradient Coil Design for Use in Cylindrical MRI Systems

Area of Science:

• Medical Imaging
• Electrical Engineering
• Computational Physics

Background:

• Magnetic resonance imaging (MRI) commonly uses stream function-based methods for gradient coil design.
• These conventional methods can introduce errors due to current density discretization and wire connections.

Purpose of the Study:

• To propose a novel gradient coil design scheme that operates directly in wire space, mitigating errors inherent in stream function approaches.
• To develop a gradient coil pattern using dedicated spiral functions for optimized field generation and minimal stray fields.

Main Methods:

• A new gradient coil design scheme working directly in the wire space was developed.
• Dedicated spiral functions were employed to define the gradient coil pattern.
• The performance of the novel spiral gradient coil was numerically evaluated and compared to a stream-function counterpart.

Main Results:

• The spiral gradient coil design demonstrated reduced inductance (20.9%) and resistance (10.5%) for the x-gradient coil, with a 26.5% improvement in the figure of merit (FoM).
• For the z-gradient coil, inductance and resistance were reduced by 15.1% and 6.7%, respectively, with a 17.7% increase in FoM.
• The spiral design resulted in a significantly sparser coil configuration compared to conventional methods.

Conclusions:

• The proposed spiral gradient coil design scheme effectively avoids system errors associated with stream function methods.
• This novel approach offers significant improvements in coil performance, including reduced inductance and resistance, and enhanced FoM.
• The direct wire distribution control leads to sparser and potentially more manufacturable gradient coils for MRI applications.