Hemodynamic Mechanisms in Venous Pulsatile Tinnitus: A 4D Flow MRI Analysis of Transverse‐Sigmoid Sinus Abnormalities

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BACKGROUND: Venous pulsatile tinnitus (VPT) is associated with transverse-sigmoid sinus (TSS) anomalies, bone dehiscence (BD), and hemodynamic disturbances. 4D Flow MRI enables comprehensive TSS evaluation, but causal relationships among TSS morphology, hemodynamics, and BD in VPT onset and progression remain unquantified. Reliable imaging predictors for VPT progression and BD's mediating role are unestablished. PURPOSE: To construct a directed acyclic graph (DAG) testing whether stenosis-induced hemodynamic abnormalities and bone changes predict VPT occurrence and 6-month progression. STUDY TYPE: Prospective longitudinal cohort study. POPULATION: 126 unilateral VPT patients (36 [31-44] years; 73.0% female) and 83 matched non-VPT participants (35 [28-42] years; 71.1% female); all VPT patients completed 6-month symptom follow-up. FIELD STRENGTH/SEQUENCE: 3 T multi-shot turbo field echo 4D Flow MRI and fast field echo phase-contrast MR venography (PC MRV). ASSESSMENT: Three blinded neuroradiologists independently assessed TSS morphology, hemodynamic indices, and petrous BD using PC MRV, 4D Flow MRI, and high-resolution CT multiplanar reconstruction. Interobserver reliability was evaluated with discrepancies resolved by consensus. STATISTICAL TESTS: Kolmogorov-Smirnov, Chi-Square, Mann-Whitney U test, FDR-corrected correlation analysis, linear/logistic regression, mediation analysis, and ROC curve analysis. SIGNIFICANCE: p < 0.05. RESULTS: 74.6% of VPT patients had 6-month progression (increased Tinnitus Handicap Inventory, THI score vs. baseline). Peak flow velocity (38.79 cm/s cut-off) independently predicted 6-month progression (area under the curve, AUC = 0.840; 95% confidence interval, CI: 0.755-0.925). TSS stenosis combined with hemodynamic parameters predicted VPT occurrence (AUC = 0.895, 95% CI: 0.855-0.936). Mediation analysis confirmed BD mediated the effect of wall shear stress on THI. Hierarchical causal pathways among TSS morphology, hemodynamics, BD, and VPT were identified to verify quantifiable DAG. DATA CONCLUSION: TSS stenosis initiates hemodynamic disturbances and bone changes, which collectively drive VPT occurrence and 6-month progression. Integrating these morphological and hemodynamic parameters yields accurate predictive models. EVIDENCE LEVEL: 4. TECHNICAL EFFICACY: Stage 3.

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