Selective Signal Suppression in Traveling Wave MPI: Focusing on Areas with Low Concentration of Magnetic Particles

Stefan Herz, Patrick Vogel, Thomas Kampf, Martin A. Rückert, Volker C. Behr, Thorsten A. Bley


Introduction: Common MPI scanners have difficulties to correctly visualize areas with a broad signal intensity spectrum due to their low signal dynamic capability. The aim of this study was to develop a selective signal suppression technique using an advanced trajectory design to circumvent this issue.

Materials and Methods: Simulations where performed for a traveling wave (TW) MPI scanner. In the so called slice-scanning mode the field free points (FFPs) travel through the scanner on a sinusoidal trajectory given by the frequencies of the dynamic linear gradient array and a perpendicular saddle coil system. The signal can be selectively suppressed by locally reducing the speed of the FFPs. Series of measurements with two point samples containing different SPIO concentrations with and without selective signal suppression technique were simulated.

Results: When imaging samples with two markedly different SPIO concentrations in the slice-scanning mode the signal of the lower concentration cannot be properly reconstructed. Applying the signal suppression technique to the area of the high concentration sample selectively reduces this signal and demarcates samples with lower concentrations.

Conclusion: A selective signal suppression technique for TWMPI is introduced which allows to focus on low SPIO concentrations in samples with a large range of tracer concentrations. This can facilitate preclinical functional imaging in the proximity of organs with high unspecific SPIO uptake such as the liver. 


TWMPI; Signal supression; Signal intensity range; Simulation

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Copyright (c) 2017 Stefan Herz

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