Heating in the MRI environment due to superparamagnetic fluid suspensions in a rotating magnetic field.
Heating in the MRI environment due to superparamagnetic fluid suspensions in a rotating magnetic field.
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DOI：
10.1016/j.jmmm.2009.10.050
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发表时间：
2010-03-01
影响因子：
2.7
通讯作者：
Zahn M
中科院分区：
文献类型：
--
作者：
Cantillon-Murphy P;Wald LL;Adalsteinsson E;Zahn M
在交变正弦或旋转磁场存在的情况下，磁性纳米颗粒会根据所施加的磁场重新调整其磁矩。这种重新排列的特征是纳米粒子的时间常数τ。随着磁场频率的增加，纳米粒子的磁矩在给定的频率Ω内落后于所施加磁场的恒定角度，单位为rad/S。与这种不对准相关的是增加块状磁性液体温度的功率耗散，这已被用作磁性纳米粒子热疗的一种方法，特别适用于低灌注组织(如乳腺)中的癌症，其中温度比体内环境温度高4°C至7°C会导致肿瘤热疗。这项工作研究了磁共振成像环境中磁性液体温度的上升，该环境的特征是大的直流场B0。用理论分析和模拟的方法预测了交变正弦磁场和旋转磁场对B0的影响。结果表明，在适当的磁流体浓度(固体体积分数0.002~0.01%)和纳米粒子半径(1~10 nm)范围内，小肿瘤(~1 cm半径)的预期温度升高。结果表明，在仔细选择旋转场或正弦场参数(场频率和幅度)的情况下，即使在磁流体饱和度不明显的低场MRI系统中，也可以发生显著的加热。这项工作表明，将低场磁共振与使用超顺磁性纳米氧化铁的磁热疗系统相结合可能是可行的。
In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle’s time constant, τ. As the magnetic field frequency is increased, the nanoparticle’s magnetic moment lags the applied magnetic field at a constant angle for a given frequency, Ω, in rad/s. Associated with this misalignment is a power dissipation that increases the bulk magnetic fluid’s temperature which has been utilized as a method of magnetic nanoparticle hyperthermia, particularly suited for cancer in low-perfusion tissue (e.g., breast) where temperature increases of between 4°C and 7°C above the ambient in vivo temperature cause tumor hyperthermia. This work examines the rise in the magnetic fluid’s temperature in the MRI environment which is characterized by a large DC field, B0. Theoretical analysis and simulation is used to predict the effect of both alternating-sinusoidal and rotating magnetic fields transverse to B0. Results are presented for the expected temperature increase in small tumors (~1 cm radius) over an appropriate range of magnetic fluid concentrations (0.002 to 0.01 solid volume fraction) and nanoparticle radii (1 to 10 nm). The results indicate that significant heating can take place, even in low-field MRI systems where magnetic fluid saturation is not significant, with careful selection of the rotating or sinusoidal field parameters (field frequency and amplitude). The work indicates that it may be feasible to combine low-field MRI with a magnetic hyperthermia system using superparamagnetic iron oxide nanoparticles.
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影响因子：
41.2
作者：
Seo, Won Seok;Lee, Jin Hyung;Dai, Hongjie
通讯作者：
Dai, Hongjie
影响因子：
2.7
作者：
Rosensweig, RE
通讯作者：
Rosensweig, RE
影响因子：
2.7
作者：
Andrä, W;d'Ambly, CG;Kaiser, WA
通讯作者：
Kaiser, WA
影响因子：
2.7
作者：
ZAHN, M;GREER, DR
通讯作者：
GREER, DR
影响因子：
2.7
作者：
Jordan, A;Scholz, R;Felix, R
通讯作者：
Felix, R