Magnetic Positioning System With CMOS Receiver for Calibrating Motion Artifacts During MRI Experiments

This article presents the first co-designed MRI imaging and magnetic positioning system for real-time dynamic motion compensation, achieving sub-millimeter tracking accuracy while preserving diagnostic image quality. The core innovation lies in a system-level co-design of an MRI imaging system and a magnetic localization system, featuring a customized receiver IC for processing magnetic signals coupled by the frontend RF coils, enabling artifact-free MRI imaging in dynamic scenarios. This integration enables a median positioning accuracy of 0.66 mm across a 40 × 40 × 50 cm³ field-of-view with a total power consumption of 997 μW. The key innovations include: 1) a time-division multiplexing scheme to enable signal detection from different coils while achieving spectral isolation between 1.4 MHz positioning signals and MRI Larmor frequencies through FPGA-synchronized blanking; 2) a dynamic calibration algorithm fusing magnetic tracking data with multi-frame MRI imaging, reducing spatial blur radius by 40% via weighted averaging; 3) an MRI-optimized Levenberg-Marquardt algorithm incorporating dynamic magnetic beacon weighting and spatial constraints, improving localization accuracy by 53% versus conventional algorithm. The system utilizes planar magnetic beacons with a dimension of 3 × 3 cm², reducing spatial occupancy compared to prior designs. This work bridges critical gaps between high-precision tracking and artifact-free MRI, enabling real-time imaging of non-autonomous motion and respiratory motion compensation, representing a paradigm shift for MRI-guided interventions.