MRI using radiofrequency magnetic field phase gradients.

Area of Science:

• Magnetic Resonance Imaging
• Physics
• Biomedical Engineering

Background:

• Conventional MRI relies on B0 magnetic field gradients, which are costly, complex, and generate noise.
• B0 gradients can induce eddy currents in conductive materials, posing potential risks to patients.

Purpose of the Study:

• To introduce and demonstrate a novel, silent, gradient-free MRI technique called Transmit Array Spatial Encoding (TRASE).
• To explore the feasibility of TRASE for medical imaging applications by evaluating its performance and potential advantages.

Main Methods:

• TRASE utilizes phase gradients of the radio-frequency (RF) field for k-space traversal, eliminating the need for B0 gradients.
• One-dimensional imaging requires two RF phase gradients, while three are sufficient for two-dimensional imaging.
• Experimental validation was performed on a 0.2 T permanent magnet human MR system.

Main Results:

• Demonstrated successful one-dimensional and two-dimensional imaging and slice selection using TRASE.
• Achieved higher spatial resolution than RF receive coil array sensitivity encoding alone.
• Observed lower spatial resolution compared to conventional B0 gradient-based MRI.

Conclusions:

• TRASE offers a silent, gradient-free alternative for MRI, potentially reducing equipment costs and complexity.
• This technique is advantageous for applications prioritizing silent operation, lower cost, or unique imaging physics.
• Further development may enhance spatial resolution for broader clinical applicability.