TREMR: Table-resonance elastography with MR.

Area of Science:

• Biomedical Engineering
• Medical Imaging Physics

Background:

• Magnetic resonance elastography (MRE) is a noninvasive technique to measure tissue stiffness.
• Conventional MRE requires specialized hardware to induce and track mechanical vibrations.
• Understanding wave propagation is key to calculating local shear stiffness.

Purpose of the Study:

• To investigate the feasibility of using patient table vibrations from low-frequency gradient switching as a mechanical driver for MRE.
• To develop a novel MRE pulse sequence for this alternative excitation method.

Main Methods:

• A specialized MRE pulse sequence was designed, incorporating a gradient lobe for mechanical resonance excitation.
• The sequence allowed controlled timing between vibration onset and velocity-encoded readout.
• Data acquisition was performed on a gelatin phantom and a healthy human brain volunteer.

Main Results:

• The developed method successfully imaged wave propagation in a gelatin phantom with identifiable stiff inserts.
• Postprocessing accurately estimated local spatial frequencies to determine shear stiffness.
• Rotational waves were observed propagating in the human brain, enabling shear stiffness mapping.

Conclusions:

• Patient table vibrations induced by gradient switching can serve as an effective mechanical driver for MRE.
• This approach offers a potentially simpler and more accessible MRE method.
• The technique is capable of mapping brain shear stiffness noninvasively.