title: Monochromatic energy computed tomography image for active intestinal hemorrhage: a model investigation.
abstract: OBJECTIVE
  To investigate the value of computed tomography (CT) spectral imaging in the evaluation of intestinal hemorrhage.
  
  
  METHODS
  Seven blood flow rates were simulated in vitro. Energy spectral CT and mixed-energy CT scans were performed for each rate (0.5, 0.4, 0.3, 0.2, 0.1, 0.05 and 0.025 mL/min). The detection rates and the contrast-to-noise ratios (CNRs) of the contrast agent extravasation regions were compared between the two scanning methods in the arterial phase (AP) and the portal venous phase (PVP). Comparisons of the CNR values between the PVP and the AP were made for each energy level and carried out using a completely random t test. A χ (2) test was used to compare the detection rates obtained from the two scanning methods.
  
  
  RESULTS
  The total detection rates for energy spectral CT and mixed-energy CT in the AP were 88.57% (31/35) and 65.71% (23/35), respectively, and the difference was significant (χ (2) = 5.185, P = 0.023); the total detection rates in the PVP were 100.00% (35/35) and 91.4% (32/35), respectively, and the difference was not significant (χ (2) = 1.393, P = 0.238). In the AP, the CNR of the contrast agent extravasation regions was 3.58 ± 2.09 on the mixed-energy CT images, but the CNRs were 8.78 ± 7.21 and 8.83 ± 6.75 at 50 and 60 keV, respectively, on the single-energy CT images, which were significantly different (3.58 ± 2.09 vs 8.78 ± 7.21, P = 0.031; 3.58 ± 2.09 vs 8.83 ± 6.75, P = 0.029). In the PVP, the differences between the CNRs at 40, 50 and 60 keV different monochromatic energy levels and the polychromatic energy images were significant (19.35 ± 10.89 vs 11.68 ± 6.38, P = 0.010; 20.82 ± 11.26 vs 11.68 ± 6.38, P = 0.001; 20.63 ± 10.07 vs 11.68 ± 6.38, P = 0.001). The CNRs at the different energy levels in the AP and the PVP were significantly different (t = -2.415, -2.380, -2.575, -2.762, -2.945, -3.157, -3.996 and -3.189).
  
  
  CONCLUSIONS
  Monochromatic energy imaging spectral CT is superior to polychromatic energy images for the detection of intestinal hemorrhage, and the detection was easier in the PVP compared with the AP.
authors.affiliation: Wen-Dong Liu, Xing-Wang Wu, Jun-Mei Hu, Bin Liu, Department of Radiology, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui Province, China.
authors.forename: Wen-Dong
authors.initials: WD
authors.lastname: Liu
authors.affiliation: Wen-Dong Liu, Xing-Wang Wu, Jun-Mei Hu, Bin Liu, Department of Radiology, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui Province, China.
authors.forename: Xing-Wang
authors.initials: XW
authors.lastname: Wu
authors.affiliation: Wen-Dong Liu, Xing-Wang Wu, Jun-Mei Hu, Bin Liu, Department of Radiology, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui Province, China.
authors.forename: Jun-Mei
authors.initials: JM
authors.lastname: Hu
authors.affiliation: Wen-Dong Liu, Xing-Wang Wu, Jun-Mei Hu, Bin Liu, Department of Radiology, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui Province, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.affiliation: Wen-Dong Liu, Xing-Wang Wu, Jun-Mei Hu, Bin Liu, Department of Radiology, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui Province, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D016009:Chi-Square Distribution; D003287:Contrast Media; D006471:Gastrointestinal Hemorrhage / Q000000981:diagnostic imaging* / Q000503:physiopathology; D066298:In Vitro Techniques; D007410:Intestinal Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007421:Intestine, Small / Q000098:blood supply* / Q000000981:diagnostic imaging*; D023421:Models, Animal; D061330:Multidetector Computed Tomography / Q000379:methods*; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D013152:Splanchnic Circulation; D013552:Swine
chemical_list: D003287:Contrast Media
keywords: Computed tomography; Monochromatic energy imaging; Small bowel bleeding; Spectral imaging