title: Dual-energy computed tomography of cruciate ligament injuries in acute knee trauma.
abstract: OBJECTIVE
  To examine dual-energy computed tomography (DECT) in evaluating cruciate ligament injuries. More specifically, the purpose was to assess the optimal keV level in DECT gemstone spectral imaging (GSI) images and to examine the usefulness of collagen-specific color mapping and dual-energy bone removal in the evaluation of cruciate ligaments and the popliteus tendon.
  
  
  METHODS
  At a level 1 trauma center, a 29-month period of emergency department DECT examinations for acute knee trauma was reviewed by two radiologists for presence of cruciate ligament injuries, visualization of the popliteus tendon and the optimal keV level in GSI images. Three different evaluating protocols (GSI, bone removal and collagen-specific color mapping) were rated. Subsequent MRI served as a reference standard for intraarticular injuries.
  
  
  RESULTS
  A total of 18 patients who had an acute knee trauma, DECT and MRI were found. On MRI, six patients had an ACL rupture. DECT's sensitivity and specificity to detect ACL rupture were 79% and 100%, respectively. The DECT vs. MRI intra- and interobserver proportions of agreement for ACL rupture were excellent or good (kappa values 0.72-0.87). Only one patient had a PCL rupture. In GSI images, the optimal keV level was 63 keV. GSI of 40-140 keV was considered to be the best evaluation protocol in the majority of cases.
  
  
  CONCLUSIONS
  DECT is a usable method to evaluate ACL in acute knee trauma patients with rather good sensitivity and high specificity. GSI is generally a better evaluation protocol than bone removal or collagen-specific color mapping in the evaluation of cruciate ligaments and popliteus tendon.
authors.affiliation: Department of Radiology, Helsinki Medical Imaging Center, Helsinki University Hospital, Töölö Trauma Center, Topeliuksenkatu 5, Helsinki, PL 266, 00029 HUS, Finland, erno.peltola@fimnet.fi.
authors.forename: Erno K
authors.initials: EK
authors.lastname: Peltola
authors.forename: Seppo K
authors.initials: SK
authors.lastname: Koskinen
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging*; D000070598:Anterior Cruciate Ligament Injuries; D001175:Arthrography / Q000379:methods; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013708:Tendon Injuries / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult