Contrast-enhanced MRI improves the diagnostic performance for vaginal fornix invasion in cervical carcinoma

Objective To investigate the added diagnostic value of contrast-enhanced MRI (CE-MRI) to T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) for evaluating vaginal fornix invasion (VFI) in cervical carcinoma (CC). Materials and methods We retrospectively enrolled 149 consecutive CC patients (training cohort) and 37 external patients (validation cohort) who underwent radical hysterectomy and preoperative MRI (T2WI, DWI, and CE-MRI). Two radiologists independently assessed VFI first using T2WI + DWI, then T2WI + DWI + CE-MRI, with histopathology as reference. Diagnostic metrics were compared with the McNemar test; interobserver agreement was evaluated via the kappa statistic. Subgroup analyses and multivariate logistic regression were performed to validate CE-MRI’s added value. Results Histopathology confirmed VFI in 68/149 patients (45.6%) in the training cohort and 6/37 (16.2%) in the external validation cohort. CE-MRI clearly visualized vaginal fornix mucosal continuity and the tumor-fornix boundary, improving lesion differentiation. Interobserver agreement improved significantly from good (κ = 0.778) to excellent (κ = 0.917) with CE-MRI (Δκ = 0.139, 95% CI: 0.062–0.220, p = 0.003). CE-MRI significantly improved diagnostic accuracy and specificity for both observers (all p < 0.001), while high sensitivity remained unchanged ( p > 0.05). Multivariate regression confirmed CE-MRI as an independent positive factor for accurate VFI diagnosis (OR = 4.05, 95% CI: 2.34–6.98, p < 0.001). Subgroup analysis demonstrated accuracy improvements across most clinical subgroups (all p < 0.05). Consistent results were obtained in the external validation cohort, with diagnostic accuracy significantly improved by CE-MRI ( p < 0.001). Conclusion Adding CE-MRI to T2WI + DWI significantly improves the diagnostic performance for VFI in CC. Critical relevance statement Combining CE-MRI with T2WI + DWI significantly improves diagnostic accuracy for VFI while enhancing interobserver agreement, which will minimize miss-staging of early-stage CC, optimize treatment planning, and ultimately improve patient outcomes by reducing recurrence risk and preserving fertility when appropriate. Key Points Accurate assessment of vaginal fornix invasion is critical but remains radiologically challenging. Contrast-enhanced MRI facilitates assessing vaginal fornix mucosal continuity and superficial invasion. Combining contrast-enhanced MRI with T2WI + DWI enhances staging accuracy for cervical carcinoma management.