title: Improving visualization of the central compartment of the hip with direct MR arthrography under axial leg traction: a feasibility study.
abstract: OBJECTIVE
  To evaluate the feasibility of a modified approach for direct magnetic resonance (MR) arthrography of the hip under leg traction in achieving a sufficient femoroacetabular interface and improving the visualization of the ligamentum teres.
  
  
  METHODS
  Forty-six MR arthrograms of 44 patients who underwent MR arthrography with and without leg traction were included into the study. Traction approach included injection of 18-27 mL of fluid (local anesthetic, contrast agent), application of weight-adapted traction load (15-23 kg), and the use of a supporting plate. Patients were instructed to report on pain and complications with an integer pain scale. Joint distraction was measured on coronal images obtained with and without traction, and two radiologists independently evaluated whether femoroacetabular cartilage layers and the ligamentum teres could be seen as distinct entities. McNemar test was used and interobserver agreement was assessed.
  
  
  RESULTS
  No patient asked for termination of the examination. There were no cases of neuropraxia. Mean difference in distraction was 3.7 mm/3.6 mm (reader 1/reader 2). Cartilage layers could be seen as distinct entities in 43/43 (93.5%/93.5%) and 6/8 (13%/17.4%) of the joints with/without traction (P < .001/P < .001), respectively. The ligamentum teres could be differentiated in 33/30 (71.7%/65.2%) cases with traction, in 33/30 (71.7%/65.2%) cases without traction (P < .999/P < .999), and in 40/37 (87%/80.4%) cases with both the techniques combined.
  
  
  CONCLUSIONS
  Traction MR arthrography is safe and technically feasible. It enabled the differentiation between femoroacetabular cartilage layers in most cases. Visualization of the ligamentum teres was optimal by combining imaging with both modalities.
authors: Section for Rheuma- and Sports Imaging, Department of Radiology, Medical University Innsbruck, Anichstraße 35, 6020 Innsbruck, Austria. Electronic address: florian.schmaranzer@student.i-med.ac.at.
authors: Florian
authors: F
authors: Schmaranzer
authors: Section for Rheuma- and Sports Imaging, Department of Radiology, Medical University Innsbruck, Anichstraße 35, 6020 Innsbruck, Austria.
authors: Andrea
authors: A
authors: Klauser
authors: Department of Radiology, District Hospital St. Johann in Tyrol, St. Johann in Tyrol, Austria.
authors: Michael
authors: M
authors: Kogler
authors: Department of Radiology, Medical University Innsbruck, Innsbruck, Austria.
authors: Benjamin
authors: B
authors: Henninger
authors: Department for Applied Systems Research and Statistics, Johannes Kepler University, Linz, Austria.
authors: Thomas
authors: T
authors: Forstner
authors: Department of Orthopedic Surgery, District Hospital St.Johann in Tyrol, St. Johann in Tyrol, Austria.
authors: Markus
authors: M
authors: Reichkendler
authors: Department of Radiology, District Hospital St. Johann in Tyrol, St. Johann in Tyrol, Austria.
authors: Ehrenfried
authors: E
authors: Schmaranzer
mesh_terms: D000465:Algorithms; D018771:Arthralgia / Q000175:diagnosis / Q000209:etiology; D001175:Arthrography / Q000379:methods; D002358:Cartilage, Articular / Q000473:pathology*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008023:Ligaments, Articular / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015588:Observer Variation; D056888:Patient Positioning / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014143:Traction / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*
keywords: MR arthrography; articular cartilage; hip joint; ligamentum teres; traction