Detection of Iron Oxide Nanoparticles for Local Chemotherapeutic Treatment Employing Coded Magnetomotive Ultrasound

摘要

Research in biomedical nanotechnology led already to a variety of applications of nanoparticles in diagnosis as well as in therapy. One of these medical applications is Magnetic Drug Targeting (MDT), a cancer treatment technique that allows local chemotherapy of cancerous tissue. For this purpose, chemotherapeutic drugs are bound to magnetic nanoparticles and are accumulated in the tumor region by external magnetic fields. Magnetic nanoparticles can indirectly serve as ultrasound contrast agents. Thus, sonographic technologies can be used as visualization technique for MDT. As nanoparticles are not visible directly using ultrasound imaging techniques due to their weak backscattering, the sonographic detection of nanoparticles has to be attributed to the detection of tissue movements, due to magnetically evoked nanoparticle movements. In this context, a sinusoidal magnetic excitation field is disadvantageous in terms of distinctness of particle induced movements, as naturally occurring movements may match the magnetic field frequency and may lead to mismeasurements. Thus, in this contribution the use of coded magnetic excitation signals, which own a major recognition value, is investigated. Here, frequency coded signals are used as magnetic excitation signals, whereat the frequency modulation is carried out with a Barker sequence offering outstanding correlation properties. We show that coded magnetic fields enable the detection of magnetic nanoparticles even if further tissue movements are superposed.