Enteric CT contrast material based on low-z atoms
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.
1. A method of acquiring a contrast enhanced X-ray computed tomography image of a subject's gastrointestinal tract, said method comprising:
(a) orally administering to said subject a diagnostically effective amount of an enteric contrast medium formulation comprising:
(i) a plurality of non-iodinated, non-barium, water-insoluble particles of the enteric contrast medium, selected from microparticles and nanoparticles, consisting of a core of an oxide of a single element with an atomic number from 12-39,
wherein a region of the image of the subject's gastrointestinal tract containing said enteric contrast medium has an 80:140 kVp CT number ratio from about 0.9 to about 1.4 and
wherein said particles are coated with a polymer which is a member selected from a poly(alkylene oxide), a poly(amino acid), a poly(ester) polymer, a polysaccharide, polyvinylpyrrolidone, a poly(vinyl) polymer, a poly(ethylene imine) polymer, a poly(acrylic) polymer, a poly(siloxane) polymer, a protein, a dendrimer and a combination thereof,
said particles constituting from about 30% (w/w) to about 70% (w/w) of said formulation; and
(ii) a pharmaceutically acceptable vehicle in which said particles are dispersed; and
(b) acquiring said X-ray computed tomography image of said gastrointestinal tract of said subject, wherein said image is an image of a region selected from the abdomen and pelvis of said subject.
2. The method according to claim 1 , wherein said oxide of a single element is silicon oxide.
3. The method of claim 1 , wherein said coating comprises poly(alkylene oxide).
4. The method of claim 1 , wherein said polymer has a molecular weight of less than about 3,000 daltons.
5. The method of claim 1 , wherein the size of said particles is from about 1 nm to about 500 microns.
6. The method of claim 5 , wherein the size of said particles is from about 1 micron to about 50 microns.
7. The method of claim 1 , wherein said enteric contrast medium has an 80:140 kVp CT number ratio from about 1.3 to about 1.4.
8. The method of claim 1 , wherein said enteric contrast medium has an 80:140 kVp CT number ratio from about 0.9 to about 1.3.
9. The method of claim 1 , wherein said formulation is an unit dosage oral formulation.
10. The method according to claim 1 , wherein said method further comprises administering to said subject a second contrast medium different from said enteric contrast medium, and said second contrast medium is administered through a route selected from oral administration, intrathecal administration, intravesicular administration, enteric administration, anal administration and intravascular administration.
11. The method according to claim 10 , wherein said second contrast medium is a member selected from an iodinated contrast medium, a Ba-, Gd- W-, Bi-, and a Ta-based contrast medium.