title: CT Image Contrast of High-Z Elements: Phantom Imaging Studies and Clinical Implications.
abstract: OBJECTIVE
  To quantify the computed tomographic (CT) image contrast produced by potentially useful contrast material elements in clinically relevant imaging conditions.
  
  
  METHODS
  Equal mass concentrations (grams of active element per milliliter of solution) of seven radiodense elements, including iodine, barium, gadolinium, tantalum, ytterbium, gold, and bismuth, were formulated as compounds in aqueous solutions. The compounds were chosen such that the active element dominated the x-ray attenuation of the solution. The solutions were imaged within a modified 32-cm CT dose index phantom at 80, 100, 120, and 140 kVp at CT. To simulate larger body sizes, 0.2-, 0.5-, and 1.0-mm-thick copper filters were applied. CT image contrast was measured and corrected for measured concentrations and presence of chlorine in some compounds.
  
  
  RESULTS
  Each element tested provided higher image contrast than iodine at some tube potential levels. Over the range of tube potentials that are clinically practical for average-sized and larger adults-that is, 100 kVp and higher-barium, gadolinium, ytterbium, and tantalum provided consistently increased image contrast compared with iodine, respectively demonstrating 39%, 56%, 34%, and 24% increases at 100 kVp; 39%, 66%, 53%, and 46% increases at 120 kVp; and 40%, 72%, 65%, and 60% increases at 140 kVp, with no added x-ray filter.
  
  
  CONCLUSIONS
  The consistently high image contrast produced with 100-140 kVp by tantalum compared with bismuth and iodine at equal mass concentration suggests that tantalum could potentially be favorable for use as a clinical CT contrast agent.
authors.affiliation: From the Radiation Systems Lab (P.F.F.), Emission Chemistry and Catalysis Lab (R.E.C., P.J.B.), Department of CT, X-ray and Functional Imaging (P.M.E.), and GE Ventures (A.S.T.), GE Global Research, One Research Circle, Niskayuna, NY 12309; and Department of Radiology and Biomedical Imaging, University of California-San Francisco, San Francisco, Calif (J.W.L., B.M.Y.).
authors.forename: Paul F
authors.initials: PF
authors.lastname: FitzGerald
authors.affiliation: From the Radiation Systems Lab (P.F.F.), Emission Chemistry and Catalysis Lab (R.E.C., P.J.B.), Department of CT, X-ray and Functional Imaging (P.M.E.), and GE Ventures (A.S.T.), GE Global Research, One Research Circle, Niskayuna, NY 12309; and Department of Radiology and Biomedical Imaging, University of California-San Francisco, San Francisco, Calif (J.W.L., B.M.Y.).
authors.forename: Robert E
authors.initials: RE
authors.lastname: Colborn
authors.affiliation: From the Radiation Systems Lab (P.F.F.), Emission Chemistry and Catalysis Lab (R.E.C., P.J.B.), Department of CT, X-ray and Functional Imaging (P.M.E.), and GE Ventures (A.S.T.), GE Global Research, One Research Circle, Niskayuna, NY 12309; and Department of Radiology and Biomedical Imaging, University of California-San Francisco, San Francisco, Calif (J.W.L., B.M.Y.).
authors.forename: Peter M
authors.initials: PM
authors.lastname: Edic
authors.affiliation: From the Radiation Systems Lab (P.F.F.), Emission Chemistry and Catalysis Lab (R.E.C., P.J.B.), Department of CT, X-ray and Functional Imaging (P.M.E.), and GE Ventures (A.S.T.), GE Global Research, One Research Circle, Niskayuna, NY 12309; and Department of Radiology and Biomedical Imaging, University of California-San Francisco, San Francisco, Calif (J.W.L., B.M.Y.).
authors.forename: Jack W
authors.initials: JW
authors.lastname: Lambert
authors.affiliation: From the Radiation Systems Lab (P.F.F.), Emission Chemistry and Catalysis Lab (R.E.C., P.J.B.), Department of CT, X-ray and Functional Imaging (P.M.E.), and GE Ventures (A.S.T.), GE Global Research, One Research Circle, Niskayuna, NY 12309; and Department of Radiology and Biomedical Imaging, University of California-San Francisco, San Francisco, Calif (J.W.L., B.M.Y.).
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Torres
authors.affiliation: From the Radiation Systems Lab (P.F.F.), Emission Chemistry and Catalysis Lab (R.E.C., P.J.B.), Department of CT, X-ray and Functional Imaging (P.M.E.), and GE Ventures (A.S.T.), GE Global Research, One Research Circle, Niskayuna, NY 12309; and Department of Radiology and Biomedical Imaging, University of California-San Francisco, San Francisco, Calif (J.W.L., B.M.Y.).
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Bonitatibus
authors.affiliation: From the Radiation Systems Lab (P.F.F.), Emission Chemistry and Catalysis Lab (R.E.C., P.J.B.), Department of CT, X-ray and Functional Imaging (P.M.E.), and GE Ventures (A.S.T.), GE Global Research, One Research Circle, Niskayuna, NY 12309; and Department of Radiology and Biomedical Imaging, University of California-San Francisco, San Francisco, Calif (J.W.L., B.M.Y.).
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Yeh
mesh_terms: D001464:Barium / Q000737:chemistry; D001729:Bismuth / Q000737:chemistry; D003287:Contrast Media / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry; D006801:Humans; D007455:Iodine / Q000737:chemistry; D019047:Phantoms, Imaging; D013635:Tantalum / Q000737:chemistry; D014057:Tomography, X-Ray Computed / Q000379:methods*; D015018:Ytterbium / Q000737:chemistry
chemical_list: D003287:Contrast Media; D001464:Barium; D013635:Tantalum; D007455:Iodine; D005682:Gadolinium; D015018:Ytterbium; D001729:Bismuth