title: Assessment of the diagnostic value of dual-energy CT and MRI in the detection of iatrogenically induced injuries of anterior cruciate ligament in a porcine model.
abstract: BACKGROUND
  Magnetic resonance imaging (MRI) is the standard of reference for the non-invasive evaluation of ligament injuries of the knee. The development of dual-energy CT (DE-CT) made it possible to differentiate between tissues of different density by two simultaneous CT measurements with different tube voltages. This approach enables DE-CT to discriminate ligament structures without intra-articular contrast media injection.                 The aims of this study were on the one hand to determine the delineation of the anterior cruciate ligament (ACL) and on the other hand to assess the diagnostic value of DE-CT and MRI in the detection of iatrogenically induced injury of the ACL in a porcine knee joint model.
  
  
  METHODS
  Twenty porcine hind legs, which were placed in a preformed cast in order to achieve a standardized position, were scanned using DE-CT. Thereafter, a 1.5-T MRI using a standard protocol was performed. The imaging procedures were repeated with the same parameters after inducing defined lesions (total or partial incision) on the ACL arthroscopically. After post-processing, two radiologists and two orthopedic surgeons first analyzed the delineation of the ACL and then, using a consensus approach, the iatrogenically induced lesions. The result of the arthrotomy was defined as the standard of reference.
  
  
  RESULTS
  The ACL could be visualized both on DE-CT and MRI in 100% of the cases. As for the MRI, the sensitivity and specificity of detecting the cruciate ligament lesion respectively compared with the defined arthrotomy was 66.7% and 78.6% for intact cruciate ligaments, 100% and 75% in the case of a complete lesion, 33.3% and 78.6% for lesions of the anteromedial bundle, and 0% and 100% for lesions of the posterolateral bundle.                 In comparison, DE-CT demonstrated a sensitivity and specificity of 66.7% and 71.4% in the case of intact cruciate ligaments, 75% and 68.8% in the case of completely discontinued ACLs, 0% and 92.9% in the case of lesions of the anteromedial bundle, and 25% and 87.5% in the case of lesions of the posterolateral bundle.
  
  
  CONCLUSIONS
  The present ex vivo experiment shows that both study modalities (DE-CT and MRI) are equal with regard to the delineation of the ACL, while MRI achieved higher sensitivity and specificity regarding iatrogenically induced complete ACL lesions. DE-CT could be a possible alternative to MRI for certain indications in the diagnosis of a knee ligament injury.
authors.affiliation: Center of Orthopaedics and Traumatology, University Medical Center Mannheim, Mannheim, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Fickert
authors.forename: M
authors.initials: M
authors.lastname: Niks
authors.forename: D J
authors.initials: DJ
authors.lastname: Dinter
authors.forename: M
authors.initials: M
authors.lastname: Hammer
authors.forename: S
authors.initials: S
authors.lastname: Weckbach
authors.forename: S O
authors.initials: SO
authors.lastname: Schoenberg
authors.forename: L
authors.initials: L
authors.lastname: Lehmann
authors.forename: S
authors.initials: S
authors.lastname: Jochum
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging / Q000473:pathology; D000070598:Anterior Cruciate Ligament Injuries; D066298:In Vitro Techniques; D007718:Knee Injuries / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*