"Crisscross" MR imaging: improved resolution by averaging signals with swapped phase-encoding axes

Area of Science:

• Medical Imaging
• Magnetic Resonance Imaging Physics

Background:

• Conventional magnetic resonance imaging (MRI) often uses fewer phase-encoding steps than readout samples.
• This leads to reduced spatial resolution in the phase-encoding direction, creating image anisotropy.
• Signal averaging enhances signal-to-noise ratio but does not resolve this directional resolution difference.

Purpose of the Study:

• To introduce a novel magnetic resonance imaging (MRI) technique to achieve equal spatial resolution in all principal directions.
• To improve image quality by addressing the inherent resolution asymmetry in conventional MRI.

Main Methods:

• The proposed method involves swapping phase- and frequency-encoding directions between successive excitations.
• Resultant data sets are then averaged, a technique termed "crisscross" imaging.
• This approach aims to achieve isotropic spatial resolution.

Main Results:

• Crisscross imaging successfully yields equal spatial resolution in both phase-encoding and frequency-encoding directions.
• The method allows for increased spatial resolution without extending the overall imaging time.
• The technique is potentially applicable to advanced MRI sequences like echo-planar imaging and 3D Fourier transform imaging.

Conclusions:

• Crisscross imaging offers a method to obtain isotropic spatial resolution in MRI.
• This technique can improve image quality and diagnostic accuracy by eliminating directional resolution bias.
• The approach is versatile and can be integrated into various advanced MRI protocols.