title: Early small-bowel ischemia: dual-energy CT improves conspicuity compared with conventional CT in a swine model.
abstract: OBJECTIVE
  To compare dual-energy computed tomography (CT) with conventional CT for the detection of small-bowel ischemia in an experimental animal model.
  
  
  METHODS
  The study was approved by the animal care and use committee and was performed in accordance with the Guide for Care and Use of Laboratory Animals issued by the National Research Council. Ischemic bowel segments (n = 8) were created in swine (n = 4) by means of surgical occlusion of distal mesenteric arteries and veins. Contrast material-enhanced dual-energy CT and conventional single-energy CT (120 kVp) sequences were performed during the portal venous phase with a single-source fast-switching dual-energy CT scanner. Attenuation values and contrast-to-noise ratios of ischemic and perfused segments on iodine material-density, monospectral dual-energy CT (51 keV, 65 keV, and 70 keV), and conventional 120-kVp CT images were compared. Linear mixed-effects models were used for comparisons.
  
  
  RESULTS
  The attenuation difference between ischemic and perfused segments was significantly greater on dual-energy 51-keV CT images than on conventional 120-kVp CT images (mean difference, 91.7 HU vs 47.6 HU; P < .0001). Conspicuity of ischemic segments was significantly greater on dual-energy iodine material-density and 51-keV CT images than on 120-kVp CT images (mean contrast-to-noise ratios, 4.9, 4.3, and 2.1, respectively; P < .0001). Although attenuation differences on dual-energy 65- and 70-keV CT images were not significantly different from those on 120-kVp images (55.0 HU, 45.8 HU, and 47.6 HU, respectively; 65 keV vs 120 kVp, P = .15; 70 keV vs 120 kVp, P = .46), the contrast-to-noise ratio was greater for the 65- and 70-keV images than for the 120-kVp images (4.4, 4.1, and 2.1 respectively; P < .0005).
  
  
  CONCLUSIONS
  Dual-energy CT significantly improved the conspicuity of the ischemic bowel compared with conventional CT by increasing attenuation differences between ischemic and perfused segments on low-kiloelectron volt and iodine material density images.
authors.affiliation: From the Departments of Radiology (T.A.P., C.L.B., M.G.L., L.A.S., B.J.W., F.T.L.), Biomedical Engineering (C.L.B.), and Medical Physics (C.L.B.), University of Wisconsin-Madison, E3/366 Clinical Science Center, 600 Highland Ave, Madison, WI 53792.
authors.forename: Theodora A
authors.initials: TA
authors.lastname: Potretzke
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Brace
authors.forename: Meghan G
authors.initials: MG
authors.lastname: Lubner
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Sampson
authors.forename: Bridgett J
authors.initials: BJ
authors.lastname: Willey
authors.forename: Fred T
authors.initials: FT
authors.lastname: Lee
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage; D018592:Cross-Over Studies; D004195:Disease Models, Animal; D007421:Intestine, Small / Q000098:blood supply / Q000000981:diagnostic imaging; D007472:Iohexol / Q000008:administration & dosage; D007511:Ischemia / Q000000981:diagnostic imaging*; D011857:Radiographic Image Interpretation, Computer-Assisted; D012680:Sensitivity and Specificity; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*; D018615:Ultrasonography, Doppler, Color
chemical_list: D003287:Contrast Media; D007472:Iohexol