Thermoacoustic concentration imaging of magnetic nanoparticles under single-pulse magnetic fields

Under a single-pulse magnetic field (SMF), we proposed a thermoacoustic (TA) concentration imaging method of magnetic nanoparticles (MNPs). This method derived the relationship between the concentration of MNPs and TA signals based on the mechanism of the TA effect. In the simulation, we ideally reconstructed the concentration map of the MNPs from the simulated TA signals. It proves the feasibility of the proposed method. In the experiment, a multi-channel acquisition system was built, and the MNP suspension with the iron concentration of 1 mg/ml was injected into two gaps of the phantom. Then, 128 TA signals were obtained by a multi-channel acquisition system. Finally, the imaging results faithfully reconstructed the cross-sectional image of the MNP area in the phantom. It is demonstrated that the TA concentration imaging of the MNPs under the SMF has the potential to achieve low-concentration MNP imaging in vivo, which provides a promising molecular imaging method for imaging MNP-labeled cancer tissues.