Quiet FLAIR at 7T MRI

Area of Science:

• Radiology and Imaging Science
• Medical Physics
• Neuroimaging

Background:

• Ultra-high-field (7T) MRI offers superior image resolution but generates significant acoustic noise, potentially impacting patient comfort and safety.
• Acoustic noise in MRI, particularly at 7T, is a major concern, necessitating strategies for reduction.
• Fluid-attenuated inversion recovery (FLAIR) sequences are crucial for detecting brain lesions, but their acoustic output can be substantial.

Purpose of the Study:

• To evaluate the effectiveness of sequence-based acoustic noise reduction in 7T cranial MRI.
• To assess the impact of noise reduction on image quality metrics, including signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), lesion conspicuity, and artifacts.
• To determine if noise reduction affects the detection rates of white matter lesions.

Main Methods:

• Fifteen patients and 5 healthy volunteers underwent 7T MRI scans.
• A FLAIR sequence was acquired both with and without sequence-based acoustic noise reduction.
• Acoustic noise levels were measured, and quantitative/qualitative image quality assessments were performed by two observers.

Main Results:

• Acoustic noise was reduced by 80%, from 92.7 dB(A) to 78.9 dB(A).
• No significant difference in artifact levels was observed.
• While SNR and CNR slightly decreased with noise reduction, lesion conspicuity and overall image quality were rated very high and slightly better for the regular sequence. White matter lesion detection rates were similar for both sequences.

Conclusions:

• Sequence-based acoustic noise reduction is feasible for 7T FLAIR imaging, achieving an 80% reduction in sound pressure.
• High diagnostic image quality can be maintained despite significant noise reduction.
• This technique offers a promising approach to improve patient comfort and safety during ultra-high-field MRI examinations.