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Imaging of Guerin Carcinoma During Magnetic Nanotherapy.

Valerii Orel et al.

Nanotechnology holds tremendous promise for the diagnostics and treatment of cancer. For example, nanotechnology applications may improve drug delivery, imaging contrast, and tumor hyperthermia compared with conventional cancer treatments. Magnetic nanocomplexes (MNC) containing iron oxide (magnetite) Fe3O4 have been used for both targeted magnetic drug delivery and induction of tumor hyperthermia. In targeted magnetic drug delivery, iron oxide containing nanoparticles are loaded with a therapeutic agent such as the antitumor anthracycline antibiotic doxorubicin (DOX). Application of a static magnetic field guides the iron oxide containing nanoparticles to a tumor and holds them there. In order to expose the particles to the highest possible traction force, magnetic drug targeting uses magnets with inhomogeneous fields. The goal of magnetic drug targeting is to concentrate the active ingredient specifically in the tumor region while at the same time minimizing the side effects of chemotherapy. In addition, tumor hyperthermia can be induced by heating the magnetic nanoparticles with a low and medium frequency external magnetic field (providing local hyperthermia), which weakens the tumor and increases the cytotoxic effects of chemotherapeutic drugs. Thus, permanent magnetic gradient fields have been used for nanoparticle-mediated drug delivery, whereas a low-frequency alternating field is required for nanoparticle induced hyperthermia. The application of the alternating magnetic field generates heat via Brownian motion, Néel relaxation and/or due to magnetic hysteresis losses. A number of imaging technologies can be used to monitor tumor biology before and after nanotherapy. Such monitoring can provide direct evidence of the distribution and accumulation of nanoparticles in the tissue of interest and help fine-tune the condition and properties of the nanotherapy. Useful imaging technologies include nuclear medical imaging, magnetic resonance imaging (MRI), and ultrasound (US). Nuclear medicine techniques can be used to estimate the effective (integrated/total) tumor perfusion. In our previous studies, using 99mTc-MIBI and 99mTc-pyrophosphate, we have shown in principle the possibility of increasing the accumulation of magnetic nanoparticles in a tumor by application of moderate radiofrequency hyperthermia and a static magnetic field.3 In our previous study nuclear medicine techniques made it possible to estimate the percentage of drug accumulation in the tumor and the integral and local speed hemodynamic parameters. However, due to the low resolution of the gamma camera and the relatively small size of the tumor, it was not possible estimate the spatial distribution of the radiopharmaceutical in the tumor with tissue heterogeneity function.

Valerii Orel et al.
Head of Medical Physics and Bioengineering Research Laboratory, National Cancer Institute/33/43 Lomonosova Street, Kyiv 03022, Ukraine
National Technical University of Ukraine 'Kyiv Polytechnic Institute'/37 Prospect Peremogy, Kyiv, 03056, Ukraine
Journal of Nanopharmaceutics and Drug Delivery. – 2014. – Vol. 2. – p. 1–11.

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