MRI by steering resonance through space.

Area of Science:

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

Background:

• Conventional MRI techniques excite spins synchronously within a defined region.
• Extreme field inhomogeneity poses a significant challenge for standard MRI acquisition.
• Compensating for field variations is crucial for high-resolution imaging.

Purpose of the Study:

• To introduce and demonstrate the feasibility of a novel MRI technique called Steering Resonance Over the Object (STEREO).
• To showcase the ability of STEREO to perform multidimensional spatiotemporal encoding.
• To validate STEREO's capability in compensating for extreme magnetic field inhomogeneity.

Main Methods:

• The STEREO technique utilizes a modulated gradient and a frequency-modulated pulse to spatially steer a resonant excitation region.
• This spatiotemporal steering enables sequential excitation and echo formation.
• Image reconstruction is achieved solely through an inverse problem solution.

Main Results:

• Feasibility of the STEREO sequence and its image reconstruction was demonstrated using phantom and human brain imaging.
• Simulations corroborated the method's potential to compensate for severe field inhomogeneities.
• Acquired images validated the principle of localized and steered excitation.

Conclusions:

• STEREO offers a significant departure from conventional MRI by enabling sequential, rather than synchronous, spin excitation.
• The ability to excite spins sequentially along a spatial trajectory allows for compensation of static and radiofrequency field variations.
• Future advancements in STEREO hold the potential for performing MRI in environments with highly inhomogeneous magnetic fields.