The Fetal Taenia–Tela Choroidea Complex: A Radiologic–Pathologic Correlation from Normal Anatomy to Dandy-Walker Malformation

Background: The taenia-tela choroidea-choroid plexus (TTC) complex has been proposed as an imaging marker to differentiate Dandy-Walker malformation (DWM) from Blake’s pouch cyst on prenatal MRI. However, radiologic-pathologic correlation remains limited. Objective: To characterize the TTC complex in normal and DWM fetuses and assess its visibility on routine prenatal MRI. Materials and methods: Nine fetal autopsy specimens with DWM and eight gestational age-matched controls with normal posterior fossa were reviewed for TTC characteristics and correlated with available MRI. Separately, 100 fetal brain MRIs (gestational age 21–38 weeks) including normal cases and posterior fossa cystic malformations were retrospectively and independently reviewed by two pediatric neuroradiologists. Visibility of the tela choroidea and fourth ventricular choroid plexus was scored as confident, borderline, or not visible. Interobserver agreement was calculated using weighted kappa with 95% confidence intervals (CI). Results: The choroid plexus in the normal fetal posterior fossa is located adjacent to the inferior medullary velum, while in DWM it is displaced inferolaterally. Histology of the tela choroidea in normal controls, demonstrates a thin tela choroidea consisting of a single-layered, arachnoid membrane, while in DWM, the tela choroidea is thick, consisting of two layers of arachnoid membrane lined by attenuated choroid plexus epithelium . On fetal MRI, the tela was confidently visible in 28 – 33% of cases, with moderate agreement (κ 0.49, 95% CI 0.34–0.62 ). The choroid plexus was confidently visible in 21 – 27% of cases, with fair agreement (κ 0.27 , 95% CI 0.09 – 0.43). Conclusion: The tela choroidea is outstretched, thickened with inferolateral displacement of the choroid plexus in DWM. TTC visibility on prenatal MRI is variable, reducing its reliability as a diagnostic marker for posterior fossa cystic malformations.