Integrated Laplacian-based phase unwrapping and background phase removal for quantitative susceptibility mapping

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biophysics
• Medical Imaging

Background:

• Quantitative susceptibility mapping (QSM) is an MRI technique measuring tissue magnetic susceptibility.
• QSM requires accurate phase unwrapping and background field removal, typically done separately.
• Existing methods can struggle with preserving low-frequency tissue signals.

Purpose of the Study:

• To develop a novel method for simultaneous phase unwrapping and background phase removal in QSM.
• To improve the accuracy and robustness of QSM data processing.
• To provide a convenient and effective solution for QSM preprocessing.

Main Methods:

• Introduction of HARPERELLA (HARmonic PhasE REmovaL using the LAplacian operator).
• Simultaneous phase unwrapping and background susceptibility removal using a single algorithm.
• Validation using numerical simulations and in vivo human brain MRI data.

Main Results:

• HARPERELLA effectively removes phase wraps and background fields.
• The method preserves low spatial frequency components from brain tissues.
• HARPERELLA demonstrates superior preservation of tissue phase signals in gray matter, white matter, and CSF compared to other techniques.

Conclusions:

• HARPERELLA offers a robust, accurate, and convenient solution for QSM phase preprocessing.
• The integrated approach simplifies QSM data analysis.
• The algorithm is available in the 'STI Suite' software package for QSM and susceptibility tensor imaging (STI).