title: Dual-energy CT virtual noncalcium technique: detecting posttraumatic bone marrow lesions--feasibility study.
abstract: OBJECTIVE
  To evaluate traumatized bone marrow with a dual-energy (DE) computed tomographic (CT) virtual noncalcium technique.
  
  
  METHODS
  In this prospective institutional review board-approved study, 21 patients with an acute knee trauma underwent DE CT and magnetic resonance (MR) imaging. A software application was used to virtually subtract calcium from the images. Presence of fractures was noted, and presence of bone bruise was rated on a four-point scale for six femoral and tibial regions by two radiologists. CT numbers were obtained in the same regions. Consensus reading of independently read MR images served as the reference standard. Image ratings and CT numbers were subjected to receiver operating characteristic curve analysis.
  
  
  RESULTS
  After exclusion of 16 regions owing to artifacts, MR imaging revealed 59 bone bruises in the remaining 236 regions (19 of 114 femoral, 40 of 122 tibial). Fractures were present in eight patients. Visual rating revealed areas under the curve of 0.886 and 0.897 in the femur and 0.974 and 0.953 in the tibia for observers 1 and 2, respectively. For CT numbers, the respective areas under the curve were 0.922 and 0.974. If scores of 1 and 2 (strong or mild bone bruise) were counted as positive, sensitivities were 86.4% and 86.4% and specificities were 94.4% and 95.5% for observers 1 and 2, respectively. The kappa statistic demonstrated good to excellent agreement (femur, kappa = 0.78; tibia, kappa = 0.87).
  
  
  CONCLUSIONS
  This DE CT virtual noncalcium technique can subtract calcium from cancellous bone, allowing bone marrow assessment and potentially making posttraumatic bone bruises of the knee detectable with CT.
authors.affiliation: Department of Diagnostic Radiology, University Hospital Freiburg, Hugstetter Str. 55, 79104 Freiburg, Germany. gregor.pache@uniklinik-freiburg.de
authors.forename: Gregor
authors.initials: G
authors.lastname: Pache
authors.forename: Bernhard
authors.initials: B
authors.lastname: Krauss
authors.forename: Peter
authors.initials: P
authors.lastname: Strohm
authors.forename: Ulrich
authors.initials: U
authors.lastname: Saueressig
authors.forename: Philipp
authors.initials: P
authors.lastname: Blanke
authors.forename: Stefan
authors.initials: S
authors.lastname: Bulla
authors.forename: Oliver
authors.initials: O
authors.lastname: Schäfer
authors.forename: Peter
authors.initials: P
authors.lastname: Helwig
authors.forename: Elmar
authors.initials: E
authors.lastname: Kotter
authors.forename: Mathias
authors.initials: M
authors.lastname: Langer
authors.forename: Tobias
authors.initials: T
authors.lastname: Baumann
mesh_terms: D000328:Adult; D001853:Bone Marrow / Q000293:injuries* / Q000473:pathology*; D005260:Female; D050723:Fractures, Bone / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007718:Knee Injuries / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult