Green's Function Total Field Inversion for Quantitative Susceptibility Mapping

Area of Science:

• Medical Imaging
• Biophysics
• Neuroimaging

Background:

• Quantitative susceptibility mapping (QSM) requires accurate background field removal for reliable tissue susceptibility quantification.
• Existing QSM methods struggle with background field estimation near organ boundaries, like the brain's surface, leading to errors.
• Interference from background magnetic fields is particularly significant in superficial brain regions such as the cerebral cortex.

Purpose of the Study:

• To introduce a novel Green's function total field inversion (gTFI) method for improved background field removal in QSM.
• To address the limitations of existing QSM techniques in handling background fields near boundaries.
• To achieve accurate whole-brain QSM reconstruction, especially in cortical regions.

Main Methods:

• Developed a novel Green's function total field inversion (gTFI) method.
• Modeled the background magnetic field using integral equations with Green's function and boundary conditions.
• Simultaneously determined boundary background field and tissue susceptibility from measured phase data, avoiding traditional filtering or regularization.

Main Results:

• The gTFI method effectively separated background fields and reconstructed whole-brain QSM images.
• gTFI demonstrated superior performance compared to existing methods, particularly in reconstructing cortical regions.
• The novel method successfully reconstructed QSM images without boundary erosion, a common issue with other techniques.

Conclusions:

• The gTFI method offers a robust solution for accurate background field removal in QSM.
• This technique significantly improves QSM accuracy in superficial brain regions like the cerebral cortex.
• gTFI provides high-quality, whole-brain QSM reconstructions without compromising boundary integrity.