Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin, Germany.
Phys Med Biol. 2010 Feb 7;55(3):623-33. doi: 10.1088/0031-9155/55/3/005. Epub 2010 Jan 13.
In magnetic heating treatments, intratumorally injected superparamagnetic iron oxide nanoparticles (MNP) exposed to an externally applied alternating magnetic field generate heat, specifically at the tumor region. This inactivates cancer cells with minimal side effects to the normal tissue. Therefore, the quantity of MNP needs to be thoroughly controlled to govern adequate heat production. Here, we demonstrate the capability of magnetorelaxometry (MRX) for the non-invasive quantification and localization of MNP accumulation in small animal models. The results of our MRX measurements using a multichannel vector magnetometer system with 304 SQUIDs (superconductive quantum interference device) on three mice hosting different carcinoma models (9L/lacZ and MD-AMB-435) are presented. The position and magnitude of the magnetic moment are reconstructed from measured spatial magnetic field distributions by a magnetic dipole model fit applying a Levenberg-Marquadt algorithm. Therewith, the center of gravity and the total amount of MNP accumulation in the mice are determined. Additionally, for a fourth mouse the distribution of MNP over individual organs and the tumor is analyzed by single-channel SQUID measurements, obtaining a sensitive spatial quantification. This study shows that magnetorelaxometry is well suited to monitor MNP accumulation before cancer therapy, with magnetic heating being an important precondition for treatment success.
在磁热治疗中，注射到肿瘤内的超顺磁氧化铁纳米颗粒（MNP）在外加交变磁场的作用下会产生热量，特别是在肿瘤区域。这会使癌细胞失活，而对正常组织的副作用最小。因此，需要彻底控制 MNP 的数量，以控制足够的产热。在这里，我们展示了磁弛豫测量（MRX）在小动物模型中定量和定位 MNP 积累的能力。我们使用带有 304 个超导量子干涉装置（SQUID）的多通道矢量磁力计系统在三只携带不同癌模型（9L/lacZ 和 MD-AMB-435）的小鼠上进行了 MRX 测量，结果表明。通过应用列文伯格-马夸特算法的磁偶极子模型拟合，从测量的空间磁场分布中重建磁矩的位置和大小。由此确定了小鼠体内 MNP 积累的重心和总量。此外，对于第四只小鼠，通过单通道 SQUID 测量分析了 MNP 在各个器官和肿瘤中的分布，实现了敏感的空间定量。这项研究表明，磁弛豫测量非常适合在癌症治疗前监测 MNP 的积累，而磁加热是治疗成功的重要前提。
