Towards Image Guided Magnetic Resonance Elastography via Active Driver Positioning Robot.

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Rheology

Background:

• Magnetic Resonance Elastography (MRE) non-invasively estimates tissue mechanical properties using MRI and induced displacements.
• Optimizing mechanical driver positioning is crucial for MRE, especially for smaller, stiffer tissues and accounting for tissue anisotropy.
• Current MRE systems face challenges with actuation frequency and precise driver placement.

Purpose of the Study:

• To demonstrate an initial prototype of an active MRE driver positioning system guided by MR imaging.
• To investigate the impact of driver positioning and vibration parameters on displacement wave patterns.
• To enable MRE for a wider range of human tissues.

Main Methods:

• Developed an active MRE driver positioning system using visual servoing under MR imaging.
• Tested three different robot configurations with an intervertebral disc (IVD) shaped gel phantom.
• Captured displacement wave patterns at various vibration angles and frequencies.

Main Results:

• Octahedral shear stress signal to noise ratio (OSS-SNR) and estimated stiffness showed statistically significant dependence on driver configuration.
• Observed variations in stiffness and OSS-SNR across different regions of the IVD phantom.
• Demonstrated the robot's capability to produce diverse driver configurations.

Conclusions:

• Driver configuration is a critical factor influencing MRE results.
• The developed active positioning system is capable of generating necessary configurations.
• This work represents the first imaging-guided active MRE driver positioning system, advancing MRE applications.