In a magnetic hyperthermia treatment, malignant cancerous cells are ablated by the heat production of magnetic nanoparticles (MNP) under an external magnetic field. This novel approach is a promising tool to eliminate the tumor cells by a higher temperature inside the tumor microenvironment. MNPs are needed inside the tumor microenvironment to increase the heat, and this could be possible with intravenous drug injection. However, tumors with necrosis regions are more resistant to drug penetration, and this can cause inadequate and non-homogeneous temperature distribution in the tumor. Hence, in this study, we used numerical methods to investigate the Spatio-temporal temperature field distribution in the necrotic tumor and its surrounding tissue. To this end, an intravenous bolus injection is used to simulate the effect of systemic drug delivery in tumors with necrosis region. Results show that the temperature field with the necrosis region with 10% of the tumor radius is more prone to higher temperature values. The hypoxia region is affected by the high temperature despite the necrosis region in the tumor. However, a broader necrosis region impedes drug penetration inside the inner layers of tumors, which leads to a lower heat generation by the MNPs. Results also demonstrate that only 15.5% of MNP concentration distributed to the necrosis with 50% of tumor radius, leading a temperature of 42∘C in the necrosis region, which is not sufficient for the tumor ablation. Therefore, the temperature distribution is dependant on the sizes of necrosis regions in tumors, and tumors with a larger necrotic region (over 20% of tumor radius) are challenging to treat with hyperthermia treatment. This study could help the future in vitro and in vivo studies of hyperthermia treatment in necrotic tumors.

中文翻译：

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肿瘤热疗中坏死区对磁性纳米粒子全身给药影响的数值模拟

在磁热疗中，恶性癌细胞在外部磁场下通过磁性纳米粒子 (MNP) 的热量产生而被消融。这种新方法是一种很有前途的工具，可以通过提高肿瘤微环境内的温度来消除肿瘤细胞。肿瘤微环境中需要 MNPs 来增加热量，这可以通过静脉注射药物来实现。然而，具有坏死区域的肿瘤对药物渗透的抵抗力更强，这会导致肿瘤内温度分布不充分和不均匀。因此，在本研究中，我们使用数值方法来研究坏死肿瘤及其周围组织的时空温度场分布。为此，静脉推注用于模拟全身给药对坏死区肿瘤的作用。结果表明，具有10%肿瘤半径的坏死区的温度场更容易出现较高的温度值。尽管肿瘤中有坏死区，但缺氧区仍受高温影响。然而，更广泛的坏死区域阻碍了药物渗透到肿瘤内层，这导致 MNP 产生的热量较低。结果还表明，只有15.5%的MNP浓度分布在50%肿瘤半径的坏死区，导致坏死区温度达到42∘C，不足以进行肿瘤消融。因此，温度分布取决于肿瘤坏死区域的大小，具有较大坏死区域（超过肿瘤半径的 20%）的肿瘤难以用热疗治疗。这项研究可能有助于未来对坏死性肿瘤进行热疗治疗的体外和体内研究。