Magnetoacoustic imaging of magnetic iron oxide nanoparticles embedded in biological tissues with microsecond magnetic stimulation

Abstract

We present an experimental study on magnetoacoustic imaging of superparamagnetic iron oxide (SPIO) nanoparticles embedded in biological tissues. In experiments, a large-current-carrying coil is used to deliver microsecond pulsed magnetic stimulation to samples. The ultrasound signals induced by magnetic forces on SPIO nanoparticles are measured by a rotating transducer. The distribution of nanoparticles is reconstructed by a back-projection imaging algorithm. The results demonstrated the feasibility to obtain cross-sectional image of magnetic nanoparticle targets with faithful dimensional and positional information, which suggests a promising tool for tomographic reconstruction of magnetic nanoparticle-labeled diseased tissues (e.g., cancerous tumor) in molecular or clinic imaging.

Figure 1

(Color online) (a) Schematic diagram for magnetic nanoparticle imaging. (b) Recorded coil current waveform with charging voltage setting at 24 kV in the magnetic stimulator. (c) A transmission electron microscopy image of iron oxide magnetic nanoparticles in the EMG 304 ferrofluid.

Figure 2

(Color online) (a) Temporal induced ultrasound signal recorded by piezoelectric transducer. (b) Photograph of the gelatin phantom containing one magnetic nanoparticle target with cylindrical geometry (c) Reconstructed image of the phantom shown in (b). (d) Photograph of the gelatin phantom containing two magnetic nanoparticle targets with cylindrical geometry and rectangular geometry. (e) Reconstructed image of the phantom shown in (d).

Figure 3

(Color online) (a) Photograph of a pork fat phantom, which contains magnetic nanoparticle target with 7.5 mm diameter. (b) Reconstructed image of the sample shown in (a). (c) Photograph of gelatin phantom, which contains magnetic nanoparticles with diluted iron content of ∼6.8 mg/ml. (d) Reconstructed image of the phantom shown in (c).