title: Toward biphasic computed tomography (CT) enteric contrast: material classification of luminal bismuth and mural iodine in a small-bowel phantom using dual-energy CT.
abstract: OBJECTIVE
  To develop dual-energy computed tomography methods for identification of hyperenhancing, hypoenhancing, and nonenhancing small-bowel pathologies.
  
  
  METHODS
  Small-bowel phantoms simulating varying patient sizes and polyp types (hyperenhancing, hypoenhancing, and nonenhancing) contained bismuth suspension in the lumen. Dual-energy CT was performed at 80/140 kV and 100/140 kV. Computed tomographic number ratios (CT numbers at low/high kilovoltage) were calculated. Two radiologists evaluated polyp detection and conspicuity using bismuth-only, iodine-only, iodine-overlay, and mixed-kilovoltage displays.
  
  
  RESULTS
  Computed tomographic ratios for bismuth and iodine did not overlap. For hyperenhancing and nonenhancing polyps at 80/140 kV, iodine-overlay display yielded higher detection rate (96%, 94%) and conspicuity score (3.5, 3.1) than mixed-kilovoltage images (88%, 68%; 1.5, 2.7). Mixed-kV images performed slightly better for hypoenhancing polyps (92%, 3.4 vs. <80%, <2.9). Similar results were observed at 100/140kV.
  
  
  CONCLUSIONS
  Dual-energy CT and a bismuth-containing enteric contrast permitted simultaneous identification of hyperenhancing, hypoenhancing, and nonenhancing polyps over a range of patient sizes.
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Mingliang
authors.initials: M
authors.lastname: Qu
authors.forename: Eric
authors.initials: E
authors.lastname: Ehman
authors.forename: Joel G
authors.initials: JG
authors.lastname: Fletcher
authors.forename: James E
authors.initials: JE
authors.lastname: Huprich
authors.forename: Amy K
authors.initials: AK
authors.lastname: Hara
authors.forename: Alvin C
authors.initials: AC
authors.lastname: Silva
authors.forename: Gianrico
authors.initials: G
authors.lastname: Farrugia
authors.forename: Paul
authors.initials: P
authors.lastname: Limburg
authors.forename: Cynthia H
authors.initials: CH
authors.lastname: McCollough
mesh_terms: D001729:Bismuth; D003287:Contrast Media; D006801:Humans; D007421:Intestine, Small / Q000000981:diagnostic imaging*; D007472:Iohexol; D019047:Phantoms, Imaging; D010865:Pilot Projects; D011857:Radiographic Image Interpretation, Computer-Assisted; D012984:Software; D013535:Suspensions; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D013535:Suspensions; D007472:Iohexol; D001729:Bismuth