Ultrafine nanoparticles as multimodal contrast agent

A noninvasive method of imaging of a lung tumor in a human patient or an animal patient, comprising the following steps:

• (i) administering to said human or animal patient, via the human or animal patient's airways, an effective amount of ultrafine nanoparticles having the following properties:
• said ultrafine nanoparticles comprise a polyorganosiloxane matrix;
• said ultrafine nanoparticles comprise a chelating agent complexing cations Mn+, M being a rare earth metal, n being an integer between 2 and 4, and optionally doping cations Dm+, D being a rare earth metal other than M, an actinide or a transition element, m being an integer between 2 and 6;
• and
• said ultrafine nanoparticles have a mean diameter having been reduced to a value between 1 and 5 nm by dissolution of all or a part of a precursor nanoparticle comprising a core made of a metal oxide or oxyhydroxide of M;
• and,
• (ii) capturing MRI images using an appropriate MRI sequence, wherein said tumor is located in said human or animal patient's lungs.

A method for monitoring the therapeutic efficacy of a therapeutic treatment of a lung tumor in a human or animal, said method comprising the following steps:

• (i) at the initiation of a treatment of a human or animal, administering an effective amount of ultrafine nanoparticles as an imaging agent, said ultrafine nanoparticles having the following properties:
• said ultrafine nanoparticles comprise a polyorganosiloxane matrix,
• said ultrafine nanoparticles also comprise a chelating agent complexing cations Mn+, M being a rare earth metal, n being an integer between 2 and 4, and optionally doping cations Dm+, D being a rare earth metal other than M, an actinide or a transition element, m being an integer between 2 and 6, and
• said ultrafine nanoparticles have a mean diameter having been reduced to a value between 1 and 5 nm by dissolution of all or part of a precursor nanoparticle comprising a core made of a metal oxide or oxyhydroxide of M,
• (ii) capturing images of the imaging agent using an appropriate imaging technique in order to visualize the tumor, said tumor being located in the lungs of said human or animal,
• (iii) repeating steps (i) and (ii) during the treatment of the human or animal, and
• (iv) comparing the change in said tumor during the treatment, thereby deducing the therapeutic efficacy of the treatment.