Magnetorelaxometry for In-Vivo Quantification of Magnetic Nanoparticle Distributions after Magnetic Drug Targeting in a Rabbit Carcinoma Model

Multi-channel magnetorelaxometry (MRX) is demonstrated to locate and quantify several foci of a magnetic nanoparticle (MNP) distribution after magnetic drug targeting (MDT) in an in-vivo rabbit carcinoma model. By this non-invasively technique MNP accumulations of lateral extensions up to 20 x 30 cm

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can easily be accessed in biological tissue. The total measurement duration of about 20 min including preparation of the rabbit and measurement of two regions of interests (ROI), tumor and thorax (liver, lung and spleen), enables a high throughput of animals. Modelling the MNP distribution either by magnetic point dipoles (ROI tumor) or by an extended, homogenously magnetized body (ROI thorax) of simple geometry, e.g. cuboid, the total magnetic moment and location of each focus is determined by minimum norm estimation. Simultaneously, vital functions like respiration and heart activity can be monitored directly and non-invasively during the MRX measurements. Thus, our MRX procedure gains valuable information for monitoring of MDT procedures in large scale animal models.