Quantitative proton density fat-fraction at 9.4 T using fast spin echo and asymmetric multi-echo gradient-echo pulse...

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering
• Medical Physics

Background:

• Quantifying proton density fat fraction (PDFF) in small abdominal organs presents challenges due to low contrast and artifacts.
• Developing advanced MRI techniques is crucial for accurate in vivo fat quantification in preclinical research.

Purpose of the Study:

• To develop and validate a novel 7-echo CSE-MRI sequence for distortion-free PDFF mapping in small animals.
• To achieve PDFF quantification comparable to established methods with potential for increased robustness.

Main Methods:

• A Fast Spin Echo Asymmetric Bipolar Multi-Gradient Echo (FSE-AbMGE) sequence was developed at 9.4T.
• The sequence integrated fast spin-echo with multi-echo gradient-echo, utilizing robust phase unwrapping and water-fat reconstruction.
• Validation involved phantoms with known PDFF and in vivo mouse experiments, comparing results with 1H-MRS.

Main Results:

• The FSE-AbMGE sequence provided high-resolution PDFF mapping with minimal artifacts.
• Phantom experiments demonstrated strong agreement with ground truth and spectroscopic values (R² > 0.98).
• In vivo studies confirmed robust water-fat separation and accurate quantification in mice.

Conclusions:

• The FSE-AbMGE sequence is suitable for accurate abdominal fat quantification in small animals.
• The method shows promise for high-field fat quantification and may be adaptable to lower-field preclinical applications.
• Further validation is needed for reproducibility and broader biological settings.