MRI features of ERSA (exercise-related signal abnormality) lesions in professional soccer players
Bibliographic record
Abstract
OBJECTIVE: This study aims to describe the prevalence, anatomy and morphology of ERSA (exercise-related signal abnormality) lesions, a previously undescribed pattern of muscle signal changes on MRI in professional soccer players with suspected acute thigh muscle injury. METHODS: A multicenter retrospective review was performed of 287 MRIs of professional soccer players referred for suspected acute thigh injury from August 2017 to February 2020. MR images were reviewed for muscle signal abnormalities corresponding to a peritendinous ovoid region or a subfascial ring of faint increased signal on fluid-sensitive MR images. Imaging features including anatomical site, morphology, and craniocaudal length were recorded. Concomitant acute muscle injury was graded in accordance with the British Athletics Muscle Injury Classification (BAMIC). RESULTS: ERSA lesions comprising a peritendinous ovoid region, a subfascial ring, or both, were identified in 40 muscles across 31/287 studies (10.8%). These lesions had a mean length of 15.8 cm and were predominantly located in the proximal or mid-portions of muscles. Affected muscles were rectus femoris (n = 22), adductor longus (n = 11), semitendinosus (n = 6) and biceps femoris (n = 1). 21/31 studies (67.7%) had a BAMIC grade 1-4 injury in a separate muscle, which were largely (81%) in a separate anatomic compartment or contralateral. CONCLUSION: ERSA lesions were evident on MRI in 10.8% of our cohort of professional soccer players referred for suspected acute thigh muscle injury. Characteristic morphology and the longitudinal length (mean 15.8 cm) distinguish ERSA lesions from recognized patterns of acute muscle injury.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".