title: Dual energy CT (DECT) of the liver: conventional versus virtual unenhanced images.
abstract: OBJECTIVE
  To compare image quality and noise of conventional unenhanced (CU) and virtual unenhanced (VU) images in patients who underwent hepatic dual energy computed tomography (DECT) and to assess potential radiation dose reduction.
  
  
  METHODS
  Forty consecutive patients were studied. Mean CU and VU image quality and noise were analyzed by two blinded radiologists using a five-point grade scale. The effective radiation dose of a triple-phase protocol (CU, arterial and DE portal phases) were compared with that of a dual-phase protocol (arterial and DE portal phases).
  
  
  RESULTS
  No significant difference in mean image quality was observed between VU (3.92 ± 0.85) and CU images (4.20 ± 0.72). A significant difference in mean image noise was observed between VU and CU (P < 0.01). The dose reduction achieved by omitting the unenhanced acquisition was 30.47 ± 7.07% (P < 0.01). In 6 patients, a complete VU liver image was not obtained.
  
  
  CONCLUSIONS
  VU images can be obtained with similar image quality as CU. This approach favors a reduction in patient's radiation exposure. Nevertheless, a complete abdominal DECT is possible only in patients with a low body mass index, due technical limitations of the present DECT systems.
authors.affiliation: Department of Cardiovascular Radiology, Ospedale San Camillo-Forlanini, Circonvallazione Gianicolense, 87, 00152, Rome, Italy, carlodececco@gmail.com.
authors.forename: Carlo Nicola
authors.initials: CN
authors.lastname: De Cecco
authors.forename: Vitaliano
authors.initials: V
authors.lastname: Buffa
authors.forename: Stefano
authors.initials: S
authors.lastname: Fedeli
authors.forename: Monica
authors.initials: M
authors.lastname: Luzietti
authors.forename: Andrea
authors.initials: A
authors.lastname: Vallone
authors.forename: Roberto
authors.initials: R
authors.lastname: Ruopoli
authors.forename: Vittorio
authors.initials: V
authors.lastname: Miele
authors.forename: Marco
authors.initials: M
authors.lastname: Rengo
authors.forename: Pasquale
authors.initials: P
authors.lastname: Paolantonio
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Maurizi Enrici
authors.forename: Andrea
authors.initials: A
authors.lastname: Laghi
authors.forename: Vincenzo
authors.initials: V
authors.lastname: David
mesh_terms: D003287:Contrast Media; D006801:Humans; D007479:Iopamidol / Q000031:analogs & derivatives*; D008099:Liver / Q000000981:diagnostic imaging*; D008113:Liver Neoplasms / Q000000981:diagnostic imaging*; D008875:Middle Aged; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods; D011856:Radiographic Image Enhancement / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; C057937:iomeprol; D007479:Iopamidol