title: MR arthrography of the hip with and without leg traction: Assessing the diagnostic performance in detection of ligamentum teres lesions with arthroscopic correlation.
abstract: OBJECTIVE
  To retrospectively assess the diagnostic performance of hip MR arthrography with and without traction in detecting ligamentum teres (LT) lesions with arthroscopic correlation and to evaluate the effect of traction on the imaging appearance of the LT.
  
  
  METHODS
  73 MR arthrograms (73 consecutive patients, mean age, 34.5 years; range, 14-55 years) obtained without and with leg traction (application of 15-23 kg, use of a supporting plate for the contralateral leg) were included. Two blinded readers independently evaluated LT lesions on MR arthrograms on separate occasions: coronal images without traction; coronal images with traction; a multiplanar traction protocol. MR findings were correlated with arthroscopic records. Sensitivity/specificity of traction and non-traction imaging was compared on coronal images with the exact McNemar test. Imaging appearance of the LT with and without traction was assessed in consensus and compared on coronal images using McNemar and McNemar-Bowker tests. (p<0.05, * corrected for type I error).
  
  
  RESULTS
  With arthroscopy 29 (40%) LT lesions were identified in 73 patients. Sensitivity was 72%/90% (without traction/with traction; p=0.25*), specificity was 89%/77% (p=0.25*) for reader 1 in assessing coronal images and for reader 2 sensitivity was 59%/86% (p=0.044*) and specificity was 93%/82% (p=0.25*). Alterations in fiber orientation, signal intensity, surface, dimension, fiber continuity after application of traction were observed in 33/73 (45%, p=0.002*), 6/73 (8%, p=0.223), 9/73 (12%, p=0.36*), 6/73 (8%, p=0.031) respectively 9/73 (12%, p=0.003) cases. Traction-related alterations in at least one criterion were observed in 41/73 (56%) cases.
  
  
  CONCLUSIONS
  Application of traction can considerably alter the imaging appearance of the LT and resulted in higher rates of true-positive and false-positive findings compared to conventional MR arthrography.
authors.affiliation: Inselspital, University of Bern, Department of Orthopaedic Surgery, Freiburgstrasse, 3010 Bern, Switzerland; Medical University Innsbruck, Department of Radiology, Anichstraße 35, 6020 Innsbruck, Austria. Electronic address: forian.schmaranzer@insel.ch.
authors.forename: Florian
authors.initials: F
authors.lastname: Schmaranzer
authors.affiliation: Medical University Innsbruck, Department of Radiology, Anichstrasse 35, 6020 Innsbruck, Austria. Electronic address: andrea.klauser@i-med.ac.at.
authors.forename: Andrea
authors.initials: A
authors.lastname: Klauser
authors.affiliation: District Hospital St. Johann in Tyrol, Department of Radiology, Bahnhofstraße 14, 6380 St. Johann in Tyrol, Austria. Electronic address: kogler@khsj.at.
authors.forename: Michael
authors.initials: M
authors.lastname: Kogler
authors.affiliation: Medical University Innsbruck, Department of Radiology, Anichstrasse 35, 6020 Innsbruck, Austria. Electronic address: benjamin.henninger@i-med.ac.at.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Henninger
authors.affiliation: Johannes Keppler University, Department for Applied Systems Research and Statistics, Altenbergerstraße 69, 4040 Linz, Austria. Electronic address: thomas.forstner@jku.at.
authors.forename: Thomas
authors.initials: T
authors.lastname: Forstner
authors.affiliation: District Hospital St. Johann in Tyrol, Department of Orthopedic Surgery, Bahnhofstraße 14, 6380 St. Johann in Tyrol, Austria. Electronic address: praxis@doc-reichkendler.at.
authors.forename: Markus
authors.initials: M
authors.lastname: Reichkendler
authors.affiliation: District Hospital St. Johann in Tyrol, Department of Radiology, Bahnhofstraße 14, 6380 St. Johann in Tyrol, Austria. Electronic address: schmaranzer@khsj.at.
authors.forename: Ehrenfried
authors.initials: E
authors.lastname: Schmaranzer
mesh_terms: D000293:Adolescent; D000328:Adult; D001175:Arthrography / Q000379:methods*; D001182:Arthroscopy / Q000379:methods*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D025981:Hip Injuries / Q000473:pathology*; D006621:Hip Joint / Q000473:pathology; D006801:Humans; D007089:Image Enhancement; D007479:Iopamidol; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D000069590:Round Ligaments / Q000293:injuries* / Q000473:pathology*; D012680:Sensitivity and Specificity; D014143:Traction; D055815:Young Adult
chemical_list: D003287:Contrast Media; D007479:Iopamidol; D019786:Gadolinium DTPA
keywords: Arthrography; Hip joint; Ligamentum teres; Magnetic resonance imaging; Traction