Magnetic particle optical imaging method based on magnetic linear dichroism effect

Magnetic particle imaging (MPI) has attracted considerable attention in recent years because it can achieve functional imaging of magnetic nanoparticles (MNPs) within biological tissues. Developing efficient MPI techniques while simultaneously enhancing imaging resolution is crucial for advancing their clinical applications. In this Letter, we propose a magnetic particle optical imaging (MPOI) method capable of quantitatively mapping the two-dimensional spatial distribution of (MNPs). This approach leverages optical imaging technology to simplify both the construction of the free-field region and the complex image reconstruction process. By extracting the second harmonic signal through phase-sensitive detection, the signal-to-noise ratio of the magnetic linear dichroism image is improved to 60 dB. The proposed method achieves highly sensitive detection of MNPs at concentrations as low as 0.01 mg/ml, along with 50 µm two-dimensional spatial resolution. These results demonstrate that the MPOI method provides a powerful platform for employing magnetic nanoparticles as magnetic labels in the metabolic imaging of living cells.