title: Possible Contrast Media Reduction with Low keV Monoenergetic Images in the Detection of Focal Liver Lesions: A Dual-Energy CT Animal Study.
abstract: OBJECTIVE
  To investigate the feasibility of dual-energy CT for contrast media (CM) reduction in the diagnosis of hypervascular and hypovascular focal liver lesions (FLL).
  
  
  METHODS
  The Institutional Animal Care and Use Committee approved this study. VX2 tumors were implanted in two different segments of the liver in 13 rabbits. After 2 weeks, two phase contrast enhanced CT scans including the arterial phase (AP) and portal-venous phase (PVP) were performed three times with 24-hour intervals with three different concentrations of iodine, 300 (I(300)), 150 (I(150)) and 75 mg I/mL (I(75)). The mean HU and standard deviation (SD) were measured in the liver, the hypervascular portion of the VX2 tumor which represented hypervascular tumors, and the central necrotic area of the VX2 tumor which represented hypovascular tumors in 140 kVp images with I(300) as a reference standard and in monoenergetic images (between 40 keV and 140 keV) with I(150) and I(75). The contrast-to-noise ratio (CNR) for FLLs and the ratio of the CNRs (CNR(ratio)) between monoenergetic image sets with I(150) and I(75), and the reference standard were calculated.
  
  
  RESULTS
  For hypervascular lesions, the CNR(ratio) was not statistically different from 1.0 between 40 keV and 70 keV images with I(150), whereas the CNR(ratio) was significantly lower than 1.0 in all keV images with I(75). For hypovascular lesions, the CNR(ratio) was similar to or higher than 1.0 between 40 keV and 80 keV with I(150) and between 40 keV and 70 keV with I(75)..
  
  
  CONCLUSIONS
  With dual-energy CT, the total amount of CM might be halved in the diagnosis of hypervascular FLLs and reduced to one-fourth in the diagnosis of hypovascular FLLs, while still preserving CNRs.
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Yong Eun
authors.initials: YE
authors.lastname: Chung
authors.affiliation: Department of Emergency medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Je Sung
authors.initials: JS
authors.lastname: You
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hye-Jeong
authors.initials: HJ
authors.lastname: Lee
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Joon Seok
authors.initials: JS
authors.lastname: Lim
authors.affiliation: Biostatistics Collaboration Unit, Department of Research Affairs, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hye Sun
authors.initials: HS
authors.lastname: Lee
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Song-Ee
authors.initials: SE
authors.lastname: Baek
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Myeong-Jin
authors.initials: MJ
authors.lastname: Kim
mesh_terms: D000818:Animals; D001027:Aortography; D003287:Contrast Media / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005240:Feasibility Studies; D007472:Iohexol / Q000008:administration & dosage; D008114:Liver Neoplasms, Experimental / Q000098:blood supply / Q000000981:diagnostic imaging*; D061330:Multidetector Computed Tomography / Q000379:methods*; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging; D011817:Rabbits; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol