Magnetic Detection and Imaging, Technical Medical Centre, University of Twente, Enschede, The Netherlands.
KIST Europe, Saarbrucken, Germany.
Biomed Phys Eng Express. 2020 Dec 21;7(1). doi: 10.1088/2057-1976/abce90.
Superparamagnetic iron oxide nanoparticles (SPIONs) are promising for clinical applications, because they have a characteristic nonlinear magnetic response when an external magnetic field is applied. This nonlinearity enables the distinct detection of SPIONs and makes measurements less sensitive to the human body and surgical steel instruments. In clinical applications, only a limited field strength for the magnetic detection is allowed. The signal to noise ratios (SNRs) of four nonlinear magnetic detection methods are compared. These methods include differential magnetometry and three variations of magnetic particle spectroscopy: frequency mixing, second harmonic detection and third harmonic detection. All methods were implemented on the same hardware and experimentally compared for various field strengths. To make the comparison fair, the same power was supplied to the excitation coil each time. In general, the SNR increases with increasing field strength. The SNR per drive field of all methods stabilizes or even decreases for field strengths above 6 mT. The second harmonic detection has the best SNR and the most room for improvement.
超顺磁氧化铁纳米粒子（SPIONs）在临床应用中具有很大的前景，因为它们在外磁场作用下具有非线性的磁响应特性。这种非线性使得 SPIONs 的检测变得更加明显，并且使测量对人体和外科手术器械的影响更小。在临床应用中，只允许使用有限的磁场强度进行磁检测。比较了四种非线性磁检测方法的信噪比（SNR）。这些方法包括微分磁力计和三种变体的磁粒子光谱学：频率混合、二次谐波检测和三次谐波检测。所有方法都在相同的硬件上实现，并针对不同的场强进行了实验比较。为了使比较公平，每次向激励线圈提供相同的功率。一般来说，SNR 随场强的增加而增加。对于超过 6 mT 的场强，所有方法的 SNR 每驱动场的稳定或甚至降低。二次谐波检测具有最佳的 SNR 和最大的改进空间。
