Efficient Water-Fat Separation for Extremity MRI at Ultra-Low-Field (0.05 T)

Area of Science:

• Medical Imaging
• Biophysics
• Biomedical Engineering

Background:

• Ultra-low-field magnetic resonance imaging (ULF-MRI) offers portable and cost-effective extremity musculoskeletal (MSK) imaging.
• Fat signal hyperintensity in ULF-MRI can obscure pathology, and prior Dixon methods have limitations at low fields.

Purpose of the Study:

• To develop an improved two-point Dixon method for efficient water-fat separation in 0.05 T extremity imaging.
• To overcome limitations of previous Dixon methods in ULF settings, such as reliance on prior phase information and long scan times.

Main Methods:

• Implemented T2* correction to address signal decay from long echo times.
• Utilized a region-growing algorithm to eliminate dependence on prior information.
• Employed multi-echo spin-echo and gradient-echo sequences for single-scan acquisition on a 0.05 T MRI scanner.

Main Results:

• Achieved approximately 3-minute scan time for phantoms and 13 minutes for in vivo extremity imaging.
• Successfully generated clear water-only and fat-only images, distinguishing muscle and fat tissues.
• Demonstrated close agreement with 3 T MRI results, validating the 0.05 T approach.

Conclusions:

• The proposed method offers a feasible solution for robust fat suppression in ULF-MRI.
• Extends ULF MRI applications for quantitative diagnosis of skeletal muscle injury and bedside follow-up of osteoarticular diseases.
• Provides a foundation for future clinical studies in MSK disease diagnosis.