The present invention provides particulate contrast media for use in CT imaging. In an exemplary embodiment, the invention provides an enteric contrast medium formulation based on particles of low-Z elements selected from microparticles and nanoparticles. 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. 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.