Bilateral asymmetry of multifidus fat infiltration in cervical ossification of the posterior longitudinal ligament: A cross-sectional MRI analysis for risk stratification and clinical decision support.

BACKGROUND

Symptom severity in cervical ossification of the posterior longitudinal ligament (OPLL) often correlates poorly with anatomical compression alone.

PURPOSE: To quantify bilateral multifidus fat infiltration asymmetry on T2-weighted MRI and develop a three-tier risk stratification system.

METHODS

This retrospective study included 115 cervical OPLL patients and 35 controls. Two blinded radiologists segmented the multifidus at the level of maximal compression (ICC 0.92-0.95). Fat infiltration asymmetry was defined as |FIR < sub > more symptomatic</sub> - FIR < sub > less symptomatic</sub>|. The optimal threshold was determined by ROC analysis, and model stability was validated via 10-fold cross-validation.

RESULTS

Asymmetry was higher in patients (5.7 ± 4.2%) than controls (1.4 ± 1.8%, p < 0.001) and correlated strongly with VAS neck pain (r = 0.78). A 10% cut-off (AUC 0.83) yielded three tiers: low (<6%), intermediate (6-12%), high (>12%). Severe-symptom prevalence rose from 3% to 84% across tiers. Continuous-type OPLL showed the greatest asymmetry (8.5%).

CONCLUSION

Bilateral multifidus fat infiltration asymmetry is a readily quantifiable MRI biomarker that surpasses canal diameter in stratifying OPLL symptom severity. Embedding the 6% and 12% thresholds into PACS reports offers radiologists an evidence-based tool for prognostic communication and surgical triage.