Optimizing accuracy and precision of micro-coil localization in active-MR tracking.

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Physics

Background:

• Active magnetic resonance (MR) tracking is crucial for precise medical interventions.
• Existing strategies like Hadamard Multiplexing and Phase-field Dithering have limitations in accuracy and precision.

Purpose of the Study:

• To evaluate the combined effect of a centroid peak detection algorithm and micro-transmit tracking on active-MR tracking accuracy and precision.
• To assess improvements when these methods are integrated with Hadamard Multiplexing and Phase-field Dithering.

Main Methods:

• Modeled the dipole magnetic field of a solenoid tracking coil and simulated MR spin excitation.
• Experimentally assessed MR-tracking accuracy and precision using a lumenless micro-coil in a 1.5-T MRI scanner for 576 orientations.
• Employed centroid pixel method and micro-transmit tracking, alongside Hadamard Multiplexing and Phase-field Dithering.

Main Results:

• The simultaneous application of centroid pixel method, micro-transmit tracking, Phase-field Dithering, and Hadamard Multiplexing achieved high MR tracking accuracy (0.52±0.41 mm) and precision (0.34 mm).
• The combined approach resulted in a tracking error smaller than the micro-coil's size, even without an internal signal source.

Conclusions:

• Micro-transmit tracking and the centroid pixel method demonstrably improve MR tracking accuracy and precision.
• The integration of these techniques with Phase-field Dithering and Hadamard Multiplexing offers superior performance over using the latter two methods alone.