Poster 105: MRI Demonstrates Similar Diagnostic Value to MR Arthrogram for Determining Labral Tear Extent up to 2 Weeks Following Shoulder Dislocation

• Published in: Orthopaedic journal of sports medicine Vol. 12; no. 7_suppl2
• Main Authors: Cong, Ting, Charles, Shaquille, Greiner, Justin, Cordle, Andrew, Andrews, Carol, Darwiche, Sophie, Reddy, Rajiv, Como, Matthew, Drain, Nicholas, Hughes, Jonathan D, Lesniak, Bryson, Lin, Albert
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01-07-2024; Sage Publications Ltd
• Subjects: Accuracy; Magnetic resonance imaging
• DOI: 10.1177/2325967124S00075
• EISSN: 2325-9671

Objectives:
The aim of this study was to determine the comparative accuracy and precision of routine Magnetic Resonance Imaging (MRI) versus magnetic resonance (MR) arthrogram in measuring labral tear size as function of time from shoulder dislocation, and to identify a time threshold after which MR arthrogram supersedes MRI in diagnostic utility.
Methods:
We retrospectively evaluated consecutive patients who underwent primary arthroscopic labral repair between 2012 and 2021 and completed a preoperative MRI or MR arthrogram of the shoulder within 60 days of injury, and subsequently underwent arthroscopic repair within 6 months of imaging. Arthroscopic labral tear size and location was used as standard comparison. Three musculoskeletal radiologists independently interpreted tear extent using clock-face convention. Accuracy and precision of MR labral tear measurements were defined by location and size of the tear, respectively. Accuracy and precision were compared between MRI and MR arthrogram, as a function of time from dislocation.
Results:
Thirty-two MRI and 65 MR arthrogram (total n=97) were independently assessed by radiologists. Multivariate analysis demonstrated that intraoperative tear size, early imaging, and arthrogram status were associated with increased MR accuracy and precision (p<0.05). Ordering surgeons preferred arthrogram for delayed imaging (p=0.018). For routine MRI, error in accuracy increased by 3.4° per day and error in precision increased by 2.3° per day (p<0.001) from time of injury. MR arthrogram, however, was not temporally influenced (Figure 1). Significant loss of accuracy and precision of routine MRI compared to MR arthrogram occurs at 2 weeks after acute shoulder dislocation.
Conclusions:
For determining shoulder labral tear size after acute dislocation, routine MRI has similar diagnostic value for measuring labral tear extent as MR arthrogram up to approximately 2 weeks postacute shoulder dislocation, after which it significantly loses accuracy and precision, possibly due to resolving posttraumatic effusion. MR arthrogram accuracy and precision were not temporally influenced.