title: Indirect MR arthrography of anterior shoulder instability in the ABER and the apprehension test positions: a prospective comparative study of two different shoulder positions during MRI using intravenous gadodiamide contrast for enhancement of the joint fluid.
abstract: OBJECTIVE
  The value of MRI for the evaluation of anterior shoulder instability can be enhanced by shoulder positions that stress the stabilising structures. The ABER position is one that has been described in combination with intra-articular gadopentetate dimeglumine arthrography. We believe that MRI in the Apprehension test position with 90 degrees abduction and maximal tolerable external rotation provides maximum tension on the anterior stabilising structures and with this technique it is sufficient to use indirect gadodiamide arthrography following intravenous injection of the contrast medium. The purpose of this study was to make a prospective comparative evaluation of the ABER and Apprehension test positions when using indirect arthrography with intravenous gadodiamide administration in shoulders with anterior instability.
  
  
  METHODS
  Sixteen patients with persistent anterior instability after recurrent shoulder dislocations were examined in an open MRI unit (0.2 T) following 0.1 mmol/kg of intravenous gadodiamide. Oblique axial T1-weighted imaging was used for analysis. Operative findings were used for correlation.
  
  
  RESULTS
  Both the ABER and the Apprehension test position were useful techniques in detecting capsulolabral pathology and Hill-Sachs lesions. The Apprehension test position produced significantly better gadodiamide-enhanced joint fluid in the region of pathology in both the capsulolabral lesion and the Hill-Sachs lesion. It also visualised the size of the Hill-Sachs lesion significantly better than did the ABER position.
  
  
  CONCLUSIONS
  MRI examination of anterior shoulder instability in the Apprehension test position was more beneficial than examination in the ABER position in visualising capsulolabral and Hill-Sachs lesions when using indirect arthrography.
authors.affiliation: Department of Orthopaedics, Uppsala University Hospital, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Wintzell
authors.forename: H
authors.initials: H
authors.lastname: Larsson
authors.forename: S
authors.initials: S
authors.lastname: Larsson
mesh_terms: D000293:Adolescent; D000328:Adult; D001175:Arthrography / Q000379:methods; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000209:etiology; D008279:Magnetic Resonance Imaging; D008297:Male; D011187:Posture; D011446:Prospective Studies; D012783:Shoulder Dislocation / Q000150:complications; D012785:Shoulder Joint / Q000473:pathology*
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA