Determination of the magnetic particle distribution in tumour tissue by means of x-ray tomography

Abstract

In biomedical applications of ferrofluids, the resulting distribution of the magnetic nanoparticles is a crucial parameter for the effect of the therapeutic approach. In order to increase the efficacy of local cancer treatments incorporating ferrofluids like magnetic drug targeting and hyperthermia, the bio-distribution of theses fluids in the respective tissue has to be optimized. Usually, the distribution of particles is determined by histological cuts of the investigated specimen, a technique which provides only local information about the overall distribution of the magnetic material, e.g. in a tumour. Radioscopic techniques based on gamma or x-rays are well established, suitable for in vivo examination and non-destructive, but only provide two-dimensional integral information in the direction of the beam. Here we have used micro-tomography—incorporating a conventional x-ray tube as well as monochromatic synchrotron radiation—as a tool for a three-dimensional analysis of the distribution of magnetic nanoparticles in biological applications. Compared to biological matter, the iron-based magnetic nanoparticles provide sufficiently high absorption for x-rays and thus serve as an intrinsic contrast agent for the examinations. The results show the principle feasibility of the method for a quantitative determination of the agglomeration behaviour of the nanoparticles within carcinogenic tissue after intravascular or intratumoural injection.