The Copenhagen Standardised MRI protocol to assess the pubic symphysis and adductor regions of athletes: outline and intratester and intertester reliability

Background There is currently no standardised MRI evaluation protocol for athletes who present with symptoms that may relate to the pubic symphysis, the pubic bones, and the adductor muscle insertions. We outline the protocol and reliability data. Material and methods Three musculoskeletal radiologists developed an 11-element MRI evaluation protocol defined according to precise criteria and illustrated in a pictorial atlas. Eighty-six male athletes (soccer players and non-soccer players) underwent standardised 3 Tesla MRI of the pelvis. Two external musculoskeletal radiologists were trained to use the protocol and pictorial atlas during two sessions of 2-4 h each. Each radiologist rated all 86 MRI independently. One radiologist evaluated the scans once, the other twice 2 months apart. Cohen. statistics were used to determine intraobserver and interobserver agreement. Results The main findings were (1) substantial intraobserver (kappa range 0.65-0.67) and moderate interobserver (kappa range 0.45-0.52) agreement in rating pubic bone marrow oedema, (2) substantial to moderate intraobserver (kappa range 0.49-0.72) and moderate-to-fair interobserver (kappa range 0.21-0.52) agreement in rating most other MRI findings, (3) slight intraobserver and interobserver (kappa range -0.06-0.05) agreement in rating adductor longus tendinopathy. Conclusions The Copenhagen Standardised MRI protocol demonstrated moderate-to-substantial reliability in rating bone marrow oedema, and varied from fair-to-substantial agreement for the majority of MRI features, but showed only slight agreement in rating adductor longus tendinopathy. This rigorous investigation also confirms that while MRI evaluation seems to provide reasonable reliability in rating pubic bone marrow oedema, the evaluation of adductor tendinopathy in a clinical and research setting needs further resolution by continued development and testing of MRI acquisition protocols.