Water/fat separate reconstruction for body quantitative susceptibility mapping in MRI

Area of Science:

• Medical Imaging
• Biophysics
• Magnetic Resonance Imaging

Background:

• Quantitative susceptibility mapping (QSM) is crucial for analyzing tissue magnetic properties.
• Conventional body QSM methods often suffer from susceptibility underestimation.
• This underestimation is partly due to the lack of phase information outside the body region.

Purpose of the Study:

• To identify the cause of susceptibility underestimation in body QSM.
• To propose and evaluate a novel water/fat separate reconstruction method to address this underestimation.

Main Methods:

• Numerical simulations were performed using conventional QSM with and without body masking.
• Water/fat separation was utilized to create separate water and fat susceptibility maps.
• The proposed water/fat separate reconstruction was compared against conventional QSM with body masking in simulations and human experiments.

Main Results:

• Conventional QSM with body masking consistently underestimated susceptibility in all simulated regions.
• QSM without body masking yielded results comparable to the ground truth.
• The proposed water/fat separate reconstruction significantly improved susceptibility estimation specifically within water tissues.
• Human experimental results corroborated the findings from numerical simulations.

Conclusions:

• The absence of external phase information is a key factor in susceptibility underestimation in conventional body QSM.
• The developed water/fat separate reconstruction method effectively mitigates susceptibility underestimation in water tissues within body QSM.
• This advancement holds promise for more accurate quantitative analysis in body MRI.