MRI detection of free-contrast agent nanoparticles

The integration of nanotechnology into biomedical imaging has significantly advanced diagnostic and theranostic capabilities. However, nanoparticle detection in imaging relies on functionalization with appropriate probes. In this work, a new approach to visualize free-label nanoparticles using MRI and MRS techniques is described, consisting of detecting by ¹H CSI specific proton signals belonging to the components naturally present in most of the nanosystems used in preclinical and clinical research.

Three different nanosystems, namely lipid-based micelles, liposomes, and perfluorocarbon-based nanoemulsions, were synthesized, characterized by high resolution NMR and then visualized by ¹H CSI at 300 MHz. Subsequently the best ¹H CSI performing system was administered to murine models of cancer to evaluate the possibility of tracking the nanosystem by looking at its proton associated signal. Furthermore, an in vitro comparison between ¹H CSI and ¹⁹F MRI was carried out.

The study successfully demonstrates the feasibility of detecting nanoparticles using MRI/MRS without probe functionalization, employing ¹H CSI. Among the nanosystems tested, the perfluorocarbon-based nanoemulsion exhibited the highest SNR. Consequently, it was evaluated in vivo, where its detection was achievable within tumors and inflamed regions via ¹H CSI, and in lymph nodes via PRESS.

These findings present a promising avenue for nanoparticle imaging in biomedical applications, offering potential enhancements to diagnostic and theranostic procedures. This non-invasive approach has the capacity to advance imaging techniques and expand the scope of nanoparticle-based biomedical research. Further exploration is necessary to fully explore the implications and applications of this method.