Single-shot spiral imaging enabled by an expanded encoding model: Demonstration in diffusion MRI.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Diffusion-Weighted Imaging (DWI)

Background:

• Single-shot spiral MRI traditionally suffers from artifacts due to long readouts.
• Improving image quality is crucial for advanced applications like diffusion tensor imaging.

Purpose of the Study:

• To enhance the quality of single-shot spiral MRI.
• To demonstrate its utility in diffusion-weighted imaging.

Main Methods:

• Developed an expanded encoding model incorporating dynamic magnetic fields, static field nonuniformity, and coil sensitivity encoding.
• Determined the encoding model using B0 mapping, sensitivity mapping, and field monitoring.
• Reconstructed images via iterative inversion of expanded signal equations for diffusion-tensor imaging.

Main Results:

• Achieved high-quality diffusion-weighted single-shot spiral imaging in vitro and in vivo.
• Demonstrated that accounting for dynamic field variations is critical for suppressing blurring, aliasing, and distortion.
• Observed enhanced image congruence, enabling data fusion and diffusion tensor analysis without coregistration.

Conclusions:

• The expanded signal model overcomes limitations of traditional spiral imaging with long readouts.
• Single-shot spiral MRI is now competitive with echo-planar imaging, offering shorter echo times and improved readout efficiency for diffusion imaging.