TITLE:
Inter Observer Variability in the Specificity of Magnetic Resonance Imaging for External Impingement of the Shoulder—Is There Agreement among Radiologists?
AUTHORS:
N. Baraza, K. Goswam, S. A. Shahban
KEYWORDS:
Shoulder Pain, Impingement, External Impingement, MRI Scanning in Shoulders, Shoulder Imaging, Specificity of MRI in External Impingement
JOURNAL NAME:
Open Access Library Journal,
Vol.4 No.4,
April
27,
2017
ABSTRACT: Purpose: External impingement in the shoulder is a condition
characterised by tenderness in the antero-lateral aspect of the shoulder on arm
elevation due to an absolute or relative decrease in the subacromial space.
Magnetic resonance imaging (MRI) is frequently utilised to confirm the
condition and rule out other differential diagnoses. We conducted a study to
look at the inter observer variability in specificity of MRI scanning in impingement
of the shoulder. Methods:
Twenty-six shoulders aged
between 20 and 34 who all presented with shoulder instability only were
included in the study. Three experienced consultant musculoskeletal
radiologists were then asked to comment on the presence or absence of impingement
on reviewing their MRI scans. Results: Radiologist 1 (R1) diagnosed 7 shoulders with
impingement and 19 shoulders without. Radiologist 2 (R2) observed that 13
shoulders had radiological signs of impingement and 13 did not, and radiologist
3 (R3) suspected impingement in 20 shoulders with 6 shoulders normal. For R1
and R2, the agreement was 0.58 with a kappa value of 0.16. Between R2 and R3,
the agreement was also 0.58 with a kappa value of 0.16. Comparing R1 and R3,
the agreement was 0.46 and the kappa value was 0.14. Across all three
radiologists, there was agreement in 8 out of the 26 MRI scans (31%) but only
in 4 out of the 26 (15.4%) did they all agree that impingement was not present.
Conclusion:
MRI should be used
judiciously in the work up of patients with external impingement of the
shoulder.