Inductive heating of ferrimagnetic particles and magnetic fluids: Physical evaluation of their potential for hyperthermia

International Journal of Hyperthermia (Impact Factor: 2.65). 11/2009; 25(7):499-511. DOI: 10.3109/02656730903287790
Source: PubMed


The potential of colloidal subdomain ferrite particle suspensions (SDP) ('magnetic fluids'), exposed to an alternating magnetic field, is evaluated for hyperthermia. Power absorption measurements of different magnetic fluids are presented in comparison to multidomain ferrite particles (MDP). Variations with frequency as well as magnetic field strength have been investigated. The experimental results clearly indicate a definite superiority of even non-optimized magnetic fluids over MDP ferrites regarding their specific absorption rate (SAR). Based on the work of [Shliomis, Pshenichnikov, Morozov, Shurubor. Magnetic properties of ferrocolloids. J Magn Magn Mater 1990; 85: 40-46 and [Hanson The frequency dependence of the complex susceptibility of magnetic fluids. J Magn Magn Mater, 1991; 96 (In press).], a solid-state physical model is applied to explain the specific properties of magnetic fluids with respect to a possible use in hyperthermia. The experimentally determined SAR data on magnetic fluids are used to estimate the heating capabilities of a magnetic induction heating technique assuming typical human dimensions and tissue parameters. It is considered that for a moderate concentration of 5 mg ferrite per gram tumour (i.e. 0.5% w/w) and clinically acceptable magnetic fields, intratumoral power absorption is comparable to RF heating with local applicators and superior to regional RF heating (by comparison with clinical SAR measurements from regional and local hyperthermia treatments). Owing to the high particle density per volume, inductive heating by magnetic fluids can improve temperature distributions in critical regions. Furthermore, localized application of magnetic fluids in a tumour might be easier and less traumatic than interstitial implantation techniques.

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Available from: Andreas Jordan
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    • "Magnetic induction hyperthermia is a new technique for interstitial hyperthermia and thermoablation based on magnetic field-induced excitation of biocompatible media [Jordan et al., 2006]. Magnetic nanoparticles (MNPs) are directly injected into the tumor tissue, where they generate heat when subjected to an alternating magnetic field (AMF) due to Brownian and Néel relaxation [Johannsen et al., 1993, 2007; Rosensweig, 2002]. Unlike laser and microwave hyperthermia treatment, magnetic hyperthermia treatment (MHT) can selectively heat a localized tumor region without damaging normal tissue because only the MNPs absorb the magnetic energy [Johannsen et al., 2007]. "
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    ABSTRACT: We investigated the relative contributions of temperature and a 300 kHz alternating magnetic field (AMF) on magnetic hyperthermia treatment (MHT). Our system consisted of an induction coil, which generated AMF by electric current flow, and a newly developed, temperature-controlled circulating water-jacketed glass bottle placed inside the coil. The AMF generator operated at a frequency of 300 kHz with variable field strength ranging from 0 to 11 mT. Four treatment conditions were employed: (A) control (37 °C, 0 mT), (B) AMF exposure (37 °C, 11 mT), (C) hyperthermia (46 °C, 0 mT), and (D) hyperthermia plus AMF exposure (46 °C, 11 mT) for 30 min. Cell viability and apoptotic death rate were estimated. The relative contributions or interactions of hyperthermia (46 °C) and AMF (11 mT) on MHT were evaluated using 2 × 2 factorial experiment analysis. Group A was statistically different (P < 0.05) from each of the other treatments. The observed effects on both cell viability and apoptotic cell death were influenced by temperature (97.36% and 92.15%, respectively), AMF (1.78% and 4.99%, respectively), and the interactions between temperature and AMF (0.25% and 2.36%, respectively). Thus, the effect of hyperthermia was significant. Also, AMF exposure itself might play a role in MHT, although these observations were made in vitro. These findings suggest a possible presence of an AMF effect during clinical magnetic hyperthermia. Bioelectromagnetics. © 2012 Wiley Periodicals, Inc.
    Full-text · Article · Feb 2013 · Bioelectromagnetics
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    • "The eddy currents losses contribution may be neglected due to the low electrical conductivity that characterizes ferroor ferrimagnetic materials and due to the small particle radius [5] [6] [7] [8] [9]. "
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    ABSTRACT: This study analytically analyzes the changes in the temperature profile of a homogenous and isotropic medium having the same thermal parameters as a muscular tissue, due to the heat released by a single magnetic nanoparticle (MNP) to its surroundings when subject to different magnetic field profiles. Exploring the temperature behavior of a heated MNP can be very useful predicting the temperature increment of it immediate surroundings. Therefore, selecting the most effective magnetic field profile (MFP) in order to reach the necessary temperature for cancer therapy is crucial in hyperthermia treatments. In order to find the temperature profile caused by the heated MNP immobilized inside a homogenous medium, the 3D diffusive-heat-flow equation (DHFE) was solved for three different types of boundary conditions (BCs). The change in the BC is caused by the different MF profiles (MFP), which are analyzed in this article. The analytic expressions are suitable for describing the transient temperature response of the medium for each case. The analysis showed that the maximum temperature increment surrounding the MNP can be achieved by radiating periodic magnetic pulses (PMPs) on it, making this MFP more effective than the conventional cosine profile.
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    • "The concept of MMH was initially described by Gilchrist et al (Gilchrist 1957) 1959 MMH with magnetic particles was carried out on rabbits in which inguinal lymph modes were successfully targeted with heat (Medal 1959) 1979 The concept of intracellular hyperthermia was first proposed by Gondon et al (Gondon 1979) 1993 Jordan A et al published the first fundamental work describing the real potential of magnetic fluids for hyperthermia (Jordan 1993) 2003~2005 MagForce Nanotechnology AG carried out the phase I clinical trials of MFH in Germany (Hauff-Maier 2007; Johannsen 2007; Wust 2006) 2005 MagForce Nanotechnology AG initiated the Phase II clinical trials of MFH in Germany 2008 The concept of Nanothermotherapy was first proposed (Gazeau 2008) 2009 The first report of post-mortem neuropathological findings of GBM patients undergone MFH was reported (Landeghem 2009) 2009 Ethical discussion on MFH for brain cancer was published (Muller 2009) "

    Full-text · Chapter · Apr 2011
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