A shielded Overhauser marker for MR tracking of interventional devices

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Interventional Radiology

Background:

• Real-time position monitoring is crucial for interventional procedures.
• Active magnetic resonance (MR) tracking techniques require effective markers for device localization.
• Existing MR tracking markers have limitations in signal enhancement and visibility.

Purpose of the Study:

• To describe improvements to an active MR tracking technique using an enhanced marker.
• To enhance the real-time position monitoring capabilities for interventional devices.
• To validate the performance of the improved active marker in laboratory and in vitro settings.

Main Methods:

• Incorporation of a small, cylindrical marker emitting an NMR signal into the tip of an interventional device.
• Enhancement of the marker's NMR signal using the Overhauser phenomenon.
• Confining saturation energy to the marker's interior for improved performance.
• Verification of marker performance in excised tissues and air using various MR imaging sequences.

Main Results:

• The improved cylindrical marker demonstrated visibility in MR images with positive contrast across different tissues and in air.
• The marker emitted a variable but enhanced signal in all orientations within the magnetic field.
• Tissue magnetization was minimally perturbed by the marker's presence.
• Successful validation of the marker's performance in laboratory and in vitro experiments.

Conclusions:

• The enhanced active MR tracking marker provides improved visibility and signal characteristics for real-time interventional procedure guidance.
• The marker's design minimizes perturbation of surrounding tissue magnetization.
• Potential applications include frameless stereotaxy and identification of inserted devices during medical procedures.