Liu Yangyang, Ke Li, Du Qiang, Zu Wanni, Jiang Ce, Zhang Yulu
School of Electrical Engineering, Shenyang University of Technology, Shenyang 110870, P.R.China.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2021 Feb 25;38(1):56-64. doi: 10.7507/1001-5515.201911010.
Medical magnetic nanoparticles are nano-medical materials with superparamagnetism, which can be collected in the tumor tissue through blood circulation, and magnetic particle imaging technology can be used to visualize the concentration of magnetic nanoparticles in the living body to achieve the purpose of tumor imaging. Based on the nonlinear magnetization characteristics of magnetic particles and the frequency characteristics of their magnetization, a differential detection method for the third harmonic of magnetic particle detection signals is proposed. It was modeled and analyzed, to study the nonlinear magnetization response characteristics of magnetic particles under alternating field, and the spectral characteristics of magnetic particle signals. At the same time, the relationship between each harmonic and the amount of medical magnetic nanoparticle samples was studied. On this basis, a signal detection experimental system was built to analyze the spectral characteristics and power spectral density of the detected signal, and to study the relationship between the signal and the excitation frequency. The signal detection experiment was carried out by the above method. The experimental results showed that under the alternating excitation field, the medical magnetic nanoparticles would generate a spike signal higher than the background sensing signal, and the magnetic particle signal existed in the odd harmonics of the detected signal spectrum. And the spectral energy was concentrated at the third harmonic, that is, the third harmonic magnetic particle signal detection that meets the medical detection requirement could be realized. In addition, the relationship between each harmonic and the particle sample volume had a positive growth relationship, and the detected medical magnetic nanoparticle sample volume could be determined according to the relationship. At the same time, the selection of the excitation frequency was limited by the sensitivity of the system, and the detection peak of the third harmonic of the detection signal was reached at the excitation frequency of 1 kHz. It provides theoretical and technical support for the detection of medical magnetic nanoparticle imaging signals in magnetic particle imaging research.
医用磁性纳米粒子是具有超顺磁性的纳米医用材料，其可通过血液循环在肿瘤组织中聚集，利用磁粒子成像技术可实现活体中磁性纳米粒子浓度的可视化，以达到肿瘤成像的目的。基于磁性粒子的非线性磁化特性及其磁化的频率特性，提出了一种磁粒子检测信号三次谐波的差分检测方法。对其进行建模与分析，研究交变磁场下磁性粒子的非线性磁化响应特性以及磁粒子信号的频谱特性。同时，研究了各谐波与医用磁性纳米粒子样本量之间的关系。在此基础上，搭建了信号检测实验系统，分析检测信号的频谱特性和功率谱密度，研究信号与激励频率之间的关系。采用上述方法进行信号检测实验。实验结果表明，在交变激励磁场下，医用磁性纳米粒子会产生高于背景传感信号的尖峰信号，且磁粒子信号存在于检测信号频谱的奇次谐波中。并且频谱能量集中在三次谐波处，即能够实现满足医用检测要求的三次谐波磁粒子信号检测。此外，各谐波与粒子样本体积之间呈正增长关系，可根据该关系确定所检测的医用磁性纳米粒子样本体积。同时，激励频率的选择受系统灵敏度的限制，在1kHz激励频率下达到检测信号三次谐波的检测峰值。为磁粒子成像研究中医用磁性纳米粒子成像信号的检测提供了理论和技术支持。
