title: MRI diagnosis of ACL bundle tears: value of oblique axial imaging.
abstract: OBJECTIVE
  To investigate the diagnostic accuracy of oblique axial intermediate weighting MR imaging in detecting partial thickness anterior cruciate ligament (ACL) bundle tears.
  
  
  METHODS
  The study protocol was approved by the institutional ethics committee. Sixty-one subjects (43 male, 18 female; mean age 27.4 years; range 9 to 57 years) with clinically suspected ACL tear or meniscal tear between September 2009 and January 2011 were studied with MRI and arthroscopy. Detection of partial tear for the ACL as a whole and for each ACL bundle by protocol A (standard orthogonal sequences) and protocol B (standard orthogonal sequences plus oblique axial intermediate weighted imaging) was compared in a blinded fashion. Performance characteristics for protocol A and protocol B were compared using sensitivity, specificity, accuracy and ROC curves. A two-tailed p value of <0.05 indicated statistical significance.
  
  
  RESULTS
  Fifteen (24.6%) normal, 15 (24.6%) partial and 31 complete tears were diagnosed by arthroscopy. Sensitivity, specificity and accuracy of protocol A for the diagnosis of partial tear of the ACL was 33%, 87% and 74%, while for protocol B the values were 87%, 87% and 87% respectively. The area under the curve (AUC) for the diagnosis of partial ACL tear and individual bundle tear was higher for protocol B, although this difference did not reach statistical significance (p > 0.05).
  
  
  CONCLUSIONS
  The addition of oblique axial imaging to standard MR imaging improves diagnostic accuracy for detecting partial tears of the ACL as well as individual bundle tears of the ACL.
authors.affiliation: Department of Imaging and Interventional Radiology, Prince of Wales Hospital, Chinese University of Hong Kong, 30-32 Ngan Shing Street, Shatin, NT, Hong Kong SAR, China. alex@sunghim.com
authors.forename: Alex W H
authors.initials: AW
authors.lastname: Ng
authors.forename: James F
authors.initials: JF
authors.lastname: Griffith
authors.forename: Esther H Y
authors.initials: EH
authors.lastname: Hung
authors.forename: Kan Yip
authors.initials: KY
authors.lastname: Law
authors.forename: Patrick S H
authors.initials: PS
authors.lastname: Yung
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000473:pathology*; D000070598:Anterior Cruciate Ligament Injuries; D002648:Child; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007718:Knee Injuries / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult