The present invention provides particulate contrast media for use in CT imaging. The contrast media are based on particles of low-Z elements. In an exemplary embodiment, the invention provides an enteric contrast medium formulation. An exemplary formulation comprises, (a) an enteric contrast medium comprising essentially water-insoluble particles of a material selected from microparticles and nanoparticles. Exemplary particles comprise a material comprising a plurality of atoms of an element with an atomic number from 6 to 52. In various embodiments, the particles are coated with a material compatible with enteric administration of the formulation to a subject in need of such administration. In an exemplary embodiment, the contrast medium is incorporated into a pharmaceutically acceptable vehicle in which the particles are suspended. The invention also provides methods for imaging of body parts simultaneously enhanced with contrast media of the invention and with other contrast media of a different type using CT imaging, including dual energy or spectral CT imaging. The invention also provides methods for the digital separation of CT signal produced by the contrast media of the invention from the CT signal produced by other contrast media or bodily tissues, to generate multiple resultant CT images with individual contrast materials subtracted or highlighted.La présente invention porte sur des milieux de contraste particulaire pour une utilisation en imagerie de tomographie assistée par ordinateur (CT). Les milieux de contraste sont basés sur des particules d'éléments de Z moins élevé. Selon un mode de réalisation donné à titre d'exemple, la présente invention porte sur une formulation de milieu de contraste entérique. Une formulation donnée à titre d'exemple comprend, (a) un milieu de contraste entérique comprenant des particules essentiellement insolubles dans l'eau d'une matière sélectionnée parmi des microparticules et des nanoparticules. Des particules données à
