title: Iodine removal in intravenous dual-energy CT-cholangiography: is virtual non-enhanced imaging effective to replace true non-enhanced imaging?
abstract: OBJECTIVE
  To evaluate whether virtual non-enhanced imaging (VNI) is effective to replace true non-enhanced imaging (TNI) applying iodine removal in intravenous dual-energy CT-cholangiography.
  
  
  METHODS
  From April 2009 until February 2010, fifteen potential donors for living-related liver transplantation (mean age 37.6±10.8 years) were included. Potential donors underwent a two-phase CT-examination of the liver. The first phase consisted of a single-energy non-enhanced CT-acquisition that provided TNI. After administration of hepatobiliary contrast agent, the second phase was performed as a dual-energy cholangiographic CT-acquisition. This provided VNI. Objective image quality (attenuation values [bile ducts and liver parenchyma] and contrast-to-noise ratio) and subjective overall image quality (1 - excellent; 5 - non diagnostic) were evaluated. Effective radiation dose was compared.
  
  
  RESULTS
  For TNI and VNI, attenuation values for bile ducts were 16.8±11.2HU and 5.5±17.0HU (p<0.05) and for liver parenchyma 55.3±8.4HU and 58.1±10.6HU (n.s.). For TNI and VNI, contrast-to-noise ratio was 2.6±0.6HU and 6.9±2.1HU (p<0.001). For VNI, subjective overall image quality was 1 in ten datasets, 2 in four datasets and 3 in one dataset. Effective radiation dose for the dual-energy cholangiographic CT-acquisition was 3.6±0.9mSv and for two-phase single-energy CT-cholangiography 5.1±1.3mSv (p<0.001).
  
  
  CONCLUSIONS
  In this study on iodine removal in intravenous dual-energy CT-cholangiography, subjective image quality is equivalent, contrast-to-noise ratio is improved and effective radiation dose is reduced when VNI is performed. The differences between TNI and VNI with respect to attenuation values seem to have limited clinical relevance and therefore we consider VNI as effective to replace TNI.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany. cmsommer@gmx.com
authors.forename: Christof M
authors.initials: CM
authors.lastname: Sommer
authors.forename: Christoph B
authors.initials: CB
authors.lastname: Schwarzwaelder
authors.forename: Wolfram
authors.initials: W
authors.lastname: Stiller
authors.forename: Sebastian T
authors.initials: ST
authors.lastname: Schindera
authors.forename: Ulrike
authors.initials: U
authors.lastname: Stampfl
authors.forename: Nadine
authors.initials: N
authors.lastname: Bellemann
authors.forename: Maria
authors.initials: M
authors.lastname: Holzschuh
authors.forename: Jan
authors.initials: J
authors.lastname: Schmidt
authors.forename: Juergen
authors.initials: J
authors.lastname: Weitz
authors.forename: Lars
authors.initials: L
authors.lastname: Grenacher
authors.forename: Hans U
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Boris A
authors.initials: BA
authors.lastname: Radeleff
mesh_terms: D000328:Adult; D002758:Cholangiography / Q000379:methods*; D003287:Contrast Media; D006801:Humans; D007458:Iodipamide / Q000031:analogs & derivatives*; D008099:Liver / Q000000981:diagnostic imaging*; D016031:Liver Transplantation / Q000000981:diagnostic imaging*; D019520:Living Donors; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
chemical_list: D003287:Contrast Media; C012386:meglumine iotroxinate; D007458:Iodipamide