Examination of Signal Behaviour of Different Nanoparticles in MRI

Daniel Sachtler, Andreas Melzer, INSITE Med, University of Applied Sciences, Gelsenkirchen, Germany &

Christian Mayer, University of Duisburg, Germany

Andreas Langer, University of Duisburg; Germany

Background

Examination of signal behaviour of nanoparticle dilutions in preparation to visualize cells and medical devices in MRI.

Material & Methods

Iron-cobalt (7 vol%; d=10nm - Liquids Research), iron-platinum and iron-oxide particles (1-4 mass%) were investigated. Dispersions were diluted with distilled water and placed into test container. Imaging was done in a Philips at 1.0 and 1.5T. Spin (TR/TE=555/15ms) and gradient (TR/TE/FA=100/6ms/50°) echo was obtained using the head coil. Signal enhancement was analyzed using OSIRIS DICOM viewer and own written software. Contrast to water was plotted against particles per µl.

Results

Iron-cobalt particles achieved contrast of up to 200% at optimum concentration (2.8E+8/µl). Signal enhancement from 2E+7 to 2E+9 part/µl. Iron-oxide particles produced signal enhancement from 5E+10 to 3.7E+12 part/µl; contrast to water up to 320% (510% if stabilized with citric acid). Optimum concentration at 5E+11 p/µl. Iron-platinum particles began to enhance signal at 1.8E+13 p/µl. Maximum concentration examined was 3.6E+14 p/µl (260% contrast to water). No artefacts, so that optimum might be at even more p/µl.

Conclusion

Iron-oxides produced best contrast. Data to be reproduced; larger amounts of particle dispersion are needed for further investigations. Tests should also be done at 3.0T. Examination of cyto-toxicity and bio-compatibility is necessary.

Keywords

nanoparticles, contrast enhanced imaging, positive contrast, USPIO, SPIO