title: Dose reduction does not affect detection of bone marrow lesions with dual-energy CT virtual noncalcium technique.
abstract: OBJECTIVE
  The aim of this study was to evaluate if a dose-reduced, dose-neutral dual-energy computed tomographic (CT) virtual noncalcium technique can equally detect posttraumatic bone marrow lesions (BMLs) of the knee.
  
  
  METHODS
  Fifty patients underwent DE CT imaging with either a standard dose (group A) or a dose equal to that of a single-energy CT scan (group B) (28% dose reduction) and magnetic resonance imaging for knee trauma workup. Calcium was virtually subtracted from the images. Two radiologists rated the presence of abnormal soft tissue-like attenuation in the bone marrow in a total of 12 femoral and tibial regions and performed Hounsfield unit measurements thereafter. Receiver-operating characteristic curve analysis was used for four-point rating scores and Hounsfield unit measurements. Fractures were classified.
  
  
  RESULTS
  Magnetic resonance imaging depicted 170 BMLs (35 femoral, 135 tibial). Mean age, number of fractures, attenuation values and number of regions with BMLs were not significantly different between the groups. Visual rating revealed overall areas under the curves of 0.983 and 0.979 for observers 1 and 2, respectively. Visual judgment was superior to attenuation measurements for femoral regions regardless of the dose applied. Analysis of variance of all CT values revealed a significant influence for the presence of edema (P < .001) but no differences for the radiation dose used (P = .424). Interobserver agreement was excellent (κ = 0.944).
  
  
  CONCLUSIONS
  Dose reduction does not affect the detectability of posttraumatic BMLs with a dual-energy CT virtual noncalcium technique, thereby providing potential additional information compared with single-energy CT imaging without additional radiation dose.
authors.affiliation: Department of Radiology, University of Freiburg, Freiburg, Germany. gregor.pache@uniklinik-freiburg.de
authors.forename: Gregor
authors.initials: G
authors.lastname: Pache
authors.forename: Stefan
authors.initials: S
authors.lastname: Bulla
authors.forename: Tobias
authors.initials: T
authors.lastname: Baumann
authors.forename: Jörg
authors.initials: J
authors.lastname: Bayer
authors.forename: Kilian
authors.initials: K
authors.lastname: Reising
authors.forename: Peter
authors.initials: P
authors.lastname: Strohm
authors.forename: Mathias
authors.initials: M
authors.lastname: Langer
authors.forename: Philipp
authors.initials: P
authors.lastname: Blanke
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001853:Bone Marrow / Q000000981:diagnostic imaging* / Q000293:injuries / Q000473:pathology; D002118:Calcium; D003288:Contusions / Q000175:diagnosis / Q000000981:diagnostic imaging; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007718:Knee Injuries / Q000175:diagnosis / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D011829:Radiation Dosage; D013382:Subtraction Technique; D013977:Tibia / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
chemical_list: D002118:Calcium