Acoustic noise reduction for spiral MRI by gradient derating.

Area of Science:

• Medical Imaging
• Biophysics

Background:

• Acoustic noise from MRI gradient coils is a significant patient comfort issue.
• Spiral MRI sequences offer faster acquisition but can be particularly noisy.

Purpose of the Study:

• To demonstrate acoustic noise reduction in spiral MRI by derating gradient performance.
• To introduce an algorithm for optimizing gradient derating parameters.
• To assess the impact on image quality and scan time.

Main Methods:

• Measured acoustic noise levels for varying gradient amplitudes and slew rates in T1-weighted spin-echo spiral scans.
• Compared full gradient trajectories with undersampled (derated) trajectories using parallel imaging reconstruction.
• Developed and compared two automatic derating algorithms: slew-rate priority and gradient-amplitude priority.

Main Results:

• Derating gradients reduced acoustic noise by an average of 16.6 dB(A) compared to full gradients.
• An undersampling factor of R=2 was required to maintain scan time with no significant loss in image Signal-to-Noise Ratio (SNR).
• Prioritizing slew rate reduction yielded the greatest acoustic noise decrease.

Conclusions:

• Gradient derating is an effective strategy to reduce spiral MRI acoustic noise with minimal impact on image quality and scan time, aided by parallel imaging.
• An automatic slew-priority derating method effectively maximizes noise reduction.