Endovascular MR-guided Renal Embolization by Using a Magnetically Assisted Remote-controlled Catheter System

Area of Science:

• Medical Imaging
• Interventional Radiology
• Biomedical Engineering

Background:

• Magnetic resonance (MR) imaging offers superior soft-tissue contrast compared to x-ray imaging.
• Interventional procedures traditionally rely on x-ray guidance, limiting real-time soft-tissue visualization.
• Developing MR-compatible catheter systems is crucial for advancing interventional MR imaging.

Purpose of the Study:

• To evaluate the feasibility of a magnetically assisted remote-controlled (MARC) catheter system for renal artery embolization under MR imaging guidance.
• To compare the performance of the MARC system with conventional x-ray guidance in vivo.
• To identify areas for improvement in the MARC system for interventional MR procedures.

Main Methods:

• The MARC catheter system, featuring a copper-braided catheter with a distal saddle coil, was tested in three farm pigs (43 kg ± 2 kg) under 1.5 T real-time MR imaging.
• Renal artery embolization was performed using the MARC system under MR guidance and with standard catheters/guidewires under x-ray guidance.
• Renal artery flow and perfusion were assessed using velocity-encoded and perfusion MR imaging before and after embolization.

Main Results:

• Successful renal artery embolization was achieved in all six kidneys under both MR and x-ray guidance.
• Mean catheterization time was longer with MR guidance (93s ± 56s) compared to x-ray guidance (60s ± 22s).
• Post-embolization changes in perfusion rates (MR: 4.9 au/sec ± 0.8; X-ray: 4.6 au/sec ± 0.6) and renal flow rates (MR: 2.1 mL/min/g ± 0.2; X-ray: 1.9 mL/min/g ± 0.2) were comparable between the two guidance methods.

Conclusions:

• The MARC catheter system is a feasible tool for renal artery catheterization and embolization under real-time MR imaging in vivo.
• Quantitative physiologic measures obtained with MR guidance were similar to those achieved with x-ray guidance.
• The MARC system shows potential for use in endovascular procedures guided by interventional MR imaging.