Bare-Metal Stent Tracking with Magnetic Particle Imaging.

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Materials Science

Background:

• Magnetic Particle Imaging (MPI) is an emerging medical imaging modality nearing clinical application.
• Cardiovascular applications, such as intraprocedural stent placement guidance, show significant potential for MPI.
• Current MPI techniques require nano-modifications for visualizing commercial medical instruments due to signal limitations.

Purpose of the Study:

• To investigate the feasibility of tracking commercial interventional devices using MPI without any nano-modifications.
• To assess the potential of MPI for visualizing and guiding cardiovascular interventions with standard medical instruments.

Main Methods:

• Tested nine endovascular metal stents for MPI signal generation in a commercial MPI scanner.
• Investigated a specific nitinol stent and its delivery system in seven scenarios using robotic positioning.
• Performed image reconstruction, calculated Mean Absolute Error (MAE) of the center of mass (COM) against ground truth, and conducted material analysis (MPS, VSM, CT).

Main Results:

• Two of nine tested stents showed sufficient MPI signal; one was selected for further study due to heating concerns.
• Successful tracking of the stent and delivery system was achieved without nano-modifications.
• MAE values were 1.49 mm (stent on delivery system), 3.70 mm (expanded stent), and 1.46 mm (delivery system alone); eddy currents likely contribute to signal generation.

Conclusions:

• Commercial medical instruments with dedicated designs can be imaged using MPI without modifications.
• This advancement opens up diverse applications for MPI in medical procedures.
• MPI imaging of unmodified instruments preserves their essential mechanical and biocompatible properties.