Gradient-based pulsed excitation for catheter tracking in MPI

Abstract

The visualization and tracking of a catheter is crucial in clinical vascular intervention process. Gradient-based pulsed excitation may enable a large field of view (FOV) and high spatial resolution in vascular magnetic particle imaging (MPI). A 5 × 5 cm2 digital phantom was designed to mimic a catheter with solidified MNPs inside vessels with suspended MNPs. The signal curve of normal vessel tissue was adapted from the synomag-D sample with a 1 wt% glycerol concentration. The catheter signal curve was adapted from the sample with 30 wt% gelatin to mimic solidified MNPs. The FFL was initially horizontal and then vertical to the digital phantom. The excitation gradient field amplitude along the FFL varied from 0.5 to 10 mT through the FOV. The signal curves of synomag-D with 1 wt% glycerol at different field amplitudes (0.5 to 10 mT) were interpolated to form the system matrix. By applying gradient-based pulsed excitation along a field-free line (FFL), a catheter molded from granulate incorporating solidified MNPs can be located according to the stripe artifacts in the system-matrix-based reconstructed images. The scan time of the proposed method can be reduced by using a smaller number of periods for signal averages if a reduction in the image quality is acceptable. Accelerated scanning may allow real-time tracking of the catheter during the clinical intervention process.