AbstractPurposeThe 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.MethodsThree 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.ResultsThe 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.ConclusionsThese 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.