MRI sign of venous varicosity aids in diagnosis of quadrilateral space syndrome: A comparative study

BACKGROUND: The diagnosis of quadrilateral space syndrome (QSS) is difficult due to its vague symptoms and lacking of simple imaging signs. This study aimed to assess the diagnostic value of venous varicosity as an indirect MRI marker for QSS. METHODS: Two blinded independent observers compared MRI findings of venous varicosity at quadrilateral space between QSS patients and controls. Consecutive QSS patients from July 2023 to July 2024 were included. Consecutive normal subjects from January 2020 to July 2024 and rotator cuff tear patients from June 2024 to July 2024 were included in control group. Venous tortuosity, engorgement, and maximum venous diameter, were evaluated on coronal and sagittal slices. Tortuous and engorged veins were recognized as varicosities. STUDY DESIGN: retrospective comparative study; level of evidence, 3. RESULTS: A total of 31 QSS patients were compared to 119 control subjects. The intraclass correlation coefficient (ICC) of intra-rater reliability for the first observer was 0.90 (95% CI, 0.85-0.94; p < 0.001) for venous tortuosity and 0.96 (95% CI, 0.93-0.98; p < 0.001) for venous engorgement. The ICC of intra-rater reliability for the second observer was 0.85 (95% CI, 0.78-0.90; p < 0.001) for venous tortuosity and 0.92 (95% CI, 0.87-0.95; p < 0.001) for venous engorgement. The ICC of inter-rater reliability was 0.85 (95% CI, 0.77-0.90; p < 0.001) for venous tortuosity and 0.82 (95% CI, 0.72-0.88; p < 0.001) for venous engorgement. There was significant difference in maximum venous diameter between QSS group and control group (3.0 ± 0.7 mm vs. 2.2 ± 0.5 mm, p < 0.001). CONCLUSION: Venous varicosity posterior to the quadrilateral space on MRI is a simple and specific sign aiding in diagnosis of QSS.