Reduced acoustic noise in diffusion tensor imaging on a compact MRI system.

Area of Science:

• Medical Imaging
• Biophysics
• Acoustics

Background:

• Acoustic noise in Magnetic Resonance Imaging (MRI) scanners, particularly during Diffusion Tensor Imaging (DTI), poses a challenge for patient comfort and data acquisition.
• Compact MRI systems offer potential advantages in terms of accessibility and cost, but their acoustic performance needs thorough investigation.

Purpose of the Study:

• To assess the feasibility of substantially reducing acoustic noise during DTI acquisition on a compact 3T (C3T) MRI scanner.
• To compare the acoustic noise levels of the C3T scanner with a conventional whole-body 3T MRI scanner.

Main Methods:

• Acoustic measurements using A-weighted decibels (dBA) were performed on both a conventional 3T MRI and the C3T scanner.
• DTI scans were acquired using sinusoidal and trapezoidal echo-planar imaging (EPI) waveforms at various gradient amplitudes and slew rates.
• Scans were conducted on phantoms and human subjects, with and without gradient-derating to simulate multi- and single-shot acquisitions.

Main Results:

• The C3T scanner demonstrated 8.5 to 15.6 dBA lower noise levels compared to the conventional 3T scanner for sinusoidal waveforms.
• Derated multi-shot DTI on the C3T achieved noise levels just 8.7 dBA above ambient, significantly quieter than non-derated single-shot DTI.
• While derating caused negligible diffusivity differences in phantoms, small biases were observed in human subjects' diffusion measurements (e.g., ADC +9.3%, FA +3.2%).

Conclusions:

• The C3T MRI scanner is feasible for whole-brain DTI acquisition with substantially reduced acoustic noise.
• Gradient-derating on the C3T offers a viable strategy for noise reduction, albeit with minor trade-offs in diffusion parameter accuracy in human subjects.