title: Pilot multi-reader study demonstrating potential for dose reduction in dual energy hepatic CT using non-linear blending of mixed kV image datasets.
abstract: OBJECTIVE
  To determine the potential for radiation dose reduction using sigmoidally-blended mixed-kV images from dual energy (DE) hepatic CT.
  
  
  METHODS
  Multiple contrast-enhanced, DE (80 kV/140 kV) datasets were reconstructed from 34 patients undergoing clinically-indicated examinations using routine CTDI(vol). Noise was inserted in projection-space to simulate six dose levels reflecting 25-100% of the original dose. Three radiologists, blinded to dose, evaluated image preference, image quality, and diagnostic confidence (scale 1 to 5) using sigmoidally-blended, mixed-kV images, identifying the lowest acceptable dose (both image quality and confidence scores ≥4). At this lowest acceptable dose, the sigmoidal, 0.5 and 0.3 linear blended images were ranked in order of preference.
  
  
  RESULTS
  Radiation dose level correlated with image preference (correlation coefficients = 0.94, 0.81, 0.94). However, 82% (28/34) and 97% (33/34) of examinations corresponding to dose reductions of 45% and 30%, respectively, yielded acceptable image quality and confidence for all three radiologists. These frequencies were similar whether or not a lesion was present. Each radiologist had specific preferences between mixed-kV image display techniques (p ≤ 0.006), with two most often preferring sigmoidally-blended images.
  
  
  CONCLUSIONS
  There is potential for further dose reduction utilizing DE hepatic CT. Radiologist visual preference for mixed-kV images is idiosyncratic.
authors.affiliation: Siemens Healthcare USA, Malvern, PA, USA.
authors.forename: Anja
authors.initials: A
authors.lastname: Apel
authors.forename: Joel G
authors.initials: JG
authors.lastname: Fletcher
authors.forename: Jeff L
authors.initials: JL
authors.lastname: Fidler
authors.forename: David M
authors.initials: DM
authors.lastname: Hough
authors.forename: Lifeng
authors.initials: L
authors.lastname: Yu
authors.forename: Luis S
authors.initials: LS
authors.lastname: Guimaraes
authors.forename: Matthias E
authors.initials: ME
authors.lastname: Bellemann
authors.forename: Cynthia H
authors.initials: CH
authors.lastname: McCollough
authors.forename: David R
authors.initials: DR
authors.lastname: Holmes
authors.forename: Christian D
authors.initials: CD
authors.lastname: Eusemann
mesh_terms: D001822:Body Burden; D003287:Contrast Media; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008107:Liver Diseases / Q000000981:diagnostic imaging*; D008297:Male; D015588:Observer Variation; D010865:Pilot Projects; D011829:Radiation Dosage; D011835:Radiation Protection / 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