MRI with phaseless encoding.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Signal Processing
• Medical Imaging Physics

Background:

• Fourier encoded MRI signals are complex and susceptible to phase variations from motion.
• These phase variations can introduce artifacts, compromising image quality.
• Existing methods struggle to fully mitigate these motion-induced artifacts.

Purpose of the Study:

• To introduce a novel phaseless encoding strategy for MRI.
• To develop a method that generates positive real MR signals, inherently robust to phase fluctuations.
• To enable artifact removal via simple magnitude calculations before Fourier transformation.

Main Methods:

• Phaseless encoding utilizes harmonic modulation of longitudinal magnetization before excitation.
• This method can be combined with Fourier encoding in complementary or the same dimensions.
• Reconstruction techniques inspired by harmonic excitation light microscopy (HELM) were adapted.

Main Results:

• Achieved artifact-free images despite significant phase fluctuations caused by motion and receiver reference instability.
• Demonstrated the ability to remove phase fluctuations by simple magnitude calculation.
• The proposed reconstruction for mixed-encoded data achieved higher resolution than previous super-resolution methods.

Conclusions:

• Spatial information can be encoded in the MR signal magnitude, making the technique insensitive to phase fluctuations.
• This phaseless encoding approach offers a robust alternative for motion-prone MRI applications.
• The method enhances image quality and resolution, particularly in challenging imaging scenarios.