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

The Fetal Taenia–Tela Choroidea Complex: A Radiologic–Pathologic Correlation from Normal Anatomy to Dandy-Walker Malformation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The Fetal Taenia–Tela Choroidea Complex: A Radiologic–Pathologic Correlation from Normal Anatomy to Dandy-Walker Malformation Caroline Rutten, Yael Fisher, Patrick Shannon, Vivek Pai, Pradeep Krishnan, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7624319/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract 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. Choroid Plexus Dandy-Walker malformation Magnetic Resonance Imaging Neuroanatomy Prenatal Diagnosis Tela choroidea Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction The taenia-tela choroidea complex (TTC) has been described inconsistently across the literature, leading to potential confusion [ 1 ]. Recently, its anatomical location has emerged as a potentially valuable imaging marker to differentiate Dandy-Walker malformation (DWM) from Blake’s pouch cyst (BPC) on prenatal ultrasound [ 2 , 3 ] and MRI [ 4 ]. The most recent imaging criteria for DWM include inferior-predominant vermian hypoplasia, an obtuse fastigial recess, an enlarged tegmentovermian angle, the tail sign (inconstant) and inferolateral displacement of the TTC and choroid plexus away from the vermis, while posterior fossa size and torcular location have been excluded [ 5 ]. In contrast, BPC is characterized by a normal-sized vermis, an enlarged tegmentovermian angle and TTC/choroid plexus positioned along the inferomedial cerebellar margin. The prognosis of DWM is highly variable, ranging from normal development to severe disability. Poor outcomes are more likely in the presence of additional central nervous system anomalies, hydrocephalus, severe vermian hypoplasia or an underlying genetic diagnosis. In contrast, BPC is generally considered benign, with a favourable neurodevelopmental outcome [ 6 , 7 ]. Prenatal distinction between these entities can be challenging. There is considerable phenotypical overlap, and mild structural abnormalities can be subtle. BPC can skew vermian height measurements, tegmentovermian angles can overlap between entities and fastigial recess assessment can be very challenging in the second trimester. The ability to distinguish these malformations early in gestation significantly impacts prognosis counseling. Despite its imaging promise, the tela choroidea remains poorly characterized and comprehensive studies correlating radiological findings with pathological examination are limited. Advancements in fetal MRI have greatly improved our ability to visualize complex neuroanatomy. However, identifying smaller, delicate structures such as the tela choroidea can remain technically challenging. Factors such as gestational age, image resolution, and motion artifacts can influence the detectability and reliability of these anatomical components in clinical practice. Given the proposed significance of the TTC/choroid plexus location in distinguishing posterior fossa malformations, a thorough investigation into the visibility and consistency of these markers on routine prenatal MRI seems warranted. This study had two main objectives. The first was to examine the histology and pathology-radiology correlation of the TTC in the normal fetal posterior fossa and in DWM. The second was to evaluate how consistently the TTC can be visualized on routine prenatal MRI, as interpreted by experienced fetal radiologists. By addressing these objectives, the study aims to improve our understanding of the normal TTC, clarify its morphological characteristics and discuss its diagnostic value in fetal posterior fossa malformations. Materials and Methods This retrospective study was approved by the institutional ethics board (REB #1000080667, REB # 80667), with a waiver of informed consent. Histology and Radiologic-Pathologic Correlation of the Tela Choroidea-Choroid Plexus Complex Cases of Dandy-Walker spectrum malformations were identified from fetal autopsy archives (2007–2024) using keyword searches for “Dandy-Walker” and “Blake’s Pouch Cyst”. Cases with complex central nervous system malformations or lacking high-quality sagittal sections of the brainstem and cerebellum were excluded. A few cases initially diagnosed as BPC on prenatal ultrasound were excluded because macroscopic examination demonstrated a normal cerebellum and the brainstem and cerebellum had been sectioned in the axial plane. A control group of normal cases was established by selecting consecutive age-matched specimens with an intact brainstem and cerebellum, and a visible membranous roof of the fourth ventricular outflow. Specimens were inked, sectioned in the sagittal plane, and photographed. To assess whether our findings were specific to DWM, we also searched for other posterior fossa malformations involving the cerebellar vermis using the keywords “Chiari” and “Joubert”. Cases were included if midsagittal sections of the brainstem and cerebellum were available and the TTC remained intact. The following variables were extracted from pathology reports: gestational age, fetal sex and results of genetic testing when available. All included specimens were reviewed for the following features: location and distribution of the choroid plexus (midline to dentate, at level of dentate and paramedian to dentate), integrity of the tela choroidea (ruptured vs. intact), spatial relationship between the tela choroidea and the inferior medullary velum, lamination pattern of the tela choroidea (unilaminar vs. bilaminar), and morphology of the cerebellum and fastigium. Selected specimens underwent immunohistochemical staining with antibodies to nestin (polyclonal), glial fibrillary acidic protein (GFAP), and cytokeratin. Availability of fetal MRI was recorded, and radiologic-pathologic correlation was performed when imaging was available. Fetal MRI Study Population A sample size of 96 MRI cases was calculated based on an estimated 50% visibility rate of the tela choroidea, with 80% power and a 5% significance level. To identify eligible cases, 972 fetal neuroimaging MRI reports between May 2018 and February 2025 were screened. Cases of normal posterior fossa were included, defined by age-appropriate cerebellar and vermian biometry and morphology with a tegmento-vermian angle < 8°. Cases of posterior fossa cystic malformation included DWM, BPC, inferior vermian hypoplasia and mega cisterna magna. Cases were excluded if they demonstrated posterior fossa abnormalities outside the DWM spectrum (Chiari 2 malformation, rhombencephalosynapsis, Joubert syndrome, posterior fossa arachnoid cyst), supratentorial anomalies or significant motion degradation precluding reliable posterior fossa assessment. Two pediatric neuroradiologists (P.K., 10 years post-fellowship experience, E.M., 20 years post-fellowship experience) blinded to initial interpretations independently evaluated the MRI studies using a standardized reading grid. They assessed two parameters: visibility of the tela choroidea and the fourth ventricular choroid plexus on T2-weighted images across all 3 orthogonal planes. Visibility was scored on a standardized three-point scale: confident, borderline confident or not confident/not visible. Fetal MRI protocol Fetal MRI protocol Our institutional protocol is as follows: sagittal, coronal and axial single-shot fast spin-echo T2-weighted images (repetition time/echo time [TR/TE]: 1500/177 ms; 3–4-mm slice thickness); axial T1 SNAP (repetition time/echo time [TR/TE]: 9500/5.3 ms; inversion time [TI]: 200 ms; 5.0-mm slice thickness); axial diffusion-weighted images (repetition time/echo time [TR/TE]: 3200/60 ms; 5.0-mm slice thickness); axial susceptibility-weighted images (TR/TE: 143/19.8 ms; 5-mm slice thickness). Images were acquired on a 1.5T MAGNETOM Avanto Fit or 3.0T MAGNETOM Skyra (Siemens Healthcare, Erlangen, Germany). Statistics Baseline characteristics were summarized using descriptive statistics: categorical data using counts and percentages and continuous data using median and range. The interreader agreement for MRI findings among the two readers was assessed using weighted Cohen’s kappa statistic, with interpretation as follows: κ ≤ 0.20, poor; >0.20 and ≤ 0.40, fair; >0.40 and ≤ 0.60, moderate; >0.60 and ≤ 0.80, good; >0.80 excellent [ 8 ]. Statistical analyses were performed using Excel software version 16.95. Results Pathologic examination Study Population Twelve autopsy cases of DWM were identified through keyword search. Three cases were excluded for technical quality or complex malformations, leaving a total of nine DWM pathology specimens (gestational age 20–24 weeks) with MRI correlation available for five. Two specimens were siblings (ID 2 and 6). The control group included eight age-matched normal posterior fossa controls (gestational age 21–24 weeks) with MRI correlation available for one. Histologic features of the tela choroidea and choroid plexus differed between groups (Table 1 ). Table 1 Characteristics of the study population, including histologic features of the tela choroidea and choroid plexus. The choroid plexus columns (“Medial to dentate,” “At dentate,” “Lateral to dentate”) indicate the location of the choroid plexus bulk relative to the dentate nucleus. MRI availability is indicated. Patients 2 and 6 are siblings. Abbreviations: DW = Dandy–Walker malformation; N = normal posterior fossa; GA = gestational age in weeks; M = male; F = female; IMV = inferior medullary velum; MRI = magnetic resonance imaging; NA = not available ID Group GA Sex Choroid plexus Tela choroidea Relationship to IMV Lamination Cerebellum Fastigium Medial to dentate At dentate Lateral to dentate MRI 1 DW 20 F Inferiorly displaced Ruptured NA Bilaminar Hypoplastic Blunted Small bulk Larger bulk None Yes 2 DW 21 M Inferiorly displaced Ruptured Outstretched Bilaminar Hypoplastic Obtuse Small bulk Larger bulk Small bulk Yes 3 DW 21 F Inferiorly displaced Ruptured NA NA Hypoplastic Blunted Small bulk Large bulk NA No 4 DW 22 F Inferiorly displaced Ruptured Outstretched NA Hypoplastic Obtuse Trace None Small bulk Yes 5 DW 23 + 4 F Inferiorly displaced Intact NA Bilaminar Hypoplastic Obtuse Small bulk NA NA No 6 DW 23 + 5 M Inferiorly displaced Ruptured Outstretched NA Hypoplastic Obtuse Minute bulk None None Yes 7 DW 24 F Inferiorly displaced Ruptured Outstretched Bilaminar Hypoplastic Obtuse Small bulk Larger bulk None Yes 8 DW 23 M Inferiorly displaced Intact Outstretched Bilaminar Hypoplastic Obtuse Small bulk Small bulk None No 9 DW 21 F Inferiorly displaced Intact NA Bilaminar Hypoplastic Blunted NA NA NA No 10 Normal 21 F Normal Ruptured Intact NA Normal Normal Small bulk Larger bulk None No 11 Normal 21 M Normal Intact Intact Delaminated roof Normal Normal Small bulk Larger bulk None No 12 Normal 21 + 4 M Normal Ruptured Intact Delaminated roof Normal Normal Small bulk Small bulk Larger bulk No 13 Normal 22 M Normal Ruptured Intact NA Normal Normal Large bulk Large bulk None No 14 Normal 22 + 2 M Normal Ruptured NA NA Normal Normal Small bulk Small bulk None No 15 Normal 22 + 2 M Normal Intact Intact Delaminated roof Normal Normal Large bulk Small bulk None No 16 Normal 24 M Normal Ruptured Intact NA Normal Normal Small bulk Larger bulk None Yes 17 Normal 24 F Normal Ruptured Intact Delaminated roof Normal Normal Large bulk Large bulk None No Normal tela choroidea-choroid plexus complex In all eight normal posterior fossa fetal specimens, the germinal trigone was located within the fourth ventricle, immediately adjacent to the choroid plexus. The tela choroidea was intact in 2/8 cases and detached in the remaining 6/8 cases. Histologically, the tela was continuous with the overlying arachnoid of the vermis. We identified a separation between the two layers of arachnoid at the ventrocaudal aspect of the inferior vermis (Fig. 1 ). The inner layer extended under the inferior vermis and supported the choroid plexus, whereas the outer layer formed the membranous roof of the fourth ventricular outflow, attaching to the taenia and converging at the obex. Immunohistochemical stains for GFAP, cytokeratin and nestin confirmed the absence of glial, neuroepithelial and endothelial cells in the membranous roof, consistent with a composition of a single meningeal layer. The choroid plexus, continuous with the inner layer of arachnoid was located in the fourth ventricle adjacent to the inferior medullary velum, extending to the ventro-caudal aspect of the vermis. In most cases, the largest choroid plexus bulk was located medial to, or at the level of the dentate nucleus, with one exception where the largest bulk was seen lateral to the dentate nucleus. Tela choroidea-choroid plexus complex in Dandy-Walker malformation Macroscopic images of the Dandy-Walker cyst were available for six cases. These all showed inferior displacement of the tela choroidea and choroid plexus (Fig. 2 , 3 ). On histology, the tela choroidea was outstretched and thickened by apposition of the inner and outer layers of arachnoid. Embryonic capillaries, positive for nestin immunohistochemical stain, were present in between the double layer of arachnoid [ 9 ]. This double-layered membrane was lined by choroid plexus epithelium (i.e. a ciliated cuboidal epithelium, cytokeratin positive, GFAP negative, continuous with fronds of choroid plexus) facing towards the fourth ventricle, with the main bulk attenuated, outstretched and laterally displaced. In two cases (ID 8 and 9), hemosiderin-laden macrophages were seen along the tela choroidea, between the arachnoid layers and within the choroid plexus. In one of these, there was evidence of an organising subarachnoid hemorrhage over the posteroinferior cerebellar vermis, without underlying cortical injury, likely dating to the early second trimester (Fig. 4 ). Radiologic-pathologic correlation MRI correlation was available for 6/15 cases (Fig. 2 , 3 ). Although the tela choroidea was not visible on MRI for these cases, inferolateral displacement of the choroid plexus was consistently noted in cases of DWM. Tela choroidea in other posterior fossa malformations Seven cases with other brainstem malformations were identified, four with Chiari 2 malformation and three with Joubert syndrome. Macroscopically, when the tela choroidea was visible, it was along the cerebellar hemispheres. The tela choroidea was inferiorly displaced, similar to DWM; however, the lamination was normal with separation between the two layers of arachnoid (Fig. 5 , 6 ). MRI reading A total of 100 fetal MRIs were included, with gestational ages ranging from 21 + 2 to 38 + 1 weeks (median 29.5 weeks). The tela was rated as confidently visible on T2-weighted images in 28–33% of cases, and as either confident or borderline confident in 53–72% (Table 2 ). Interobserver agreement was moderate (κ = 0.49). On gradient-echo images, the tela choroidea was only visible in 12–20% of cases, with poor agreement between readers (κ = 0.19). The choroid plexus was rated as confidently visible in 23–30% of cases, with fair agreement (κ = 0.27). When asked whether the orientation of the taenia–tela choroidea complex aided diagnosis or differentiation of BPC from DWM, one reader found it useful in a single case, and the other in none. Agreement for final diagnostic categorization was excellent across both readers. Table 2 Interobserver agreement for tela choroidea and choroid plexus visibility on prenatal MRI. Data are presented as number of cases per category for each reader with Cohen’s kappa values indicating agreement. Abbreviations: CI = confidence interval; TTC = Taenia-tela choroidea complex Item Category Reader 1 (n) Reader 2 (n) Weighted k (95% CI) Tela Choroidea Visibility on T2-weighted images Confident 28 33 0.49 (0.34–0.62) Borderline confident 25 39 Not confident / Not visible 47 28 Tela Choroidea Visibility on gradient echo images Visible 20 12 0.19 (-0.04-0.42) Not visible 80 88 Choroid Plexus Visibility Confident 23 30 0.27 (0.10–0.44) Borderline confident 40 58 Not confident / Not visible 37 12 Usefulness of TTC orientation Yes 0 1 No 100 99 Final diagnosis Normal 73 75 0.83 (0.74–0.94) Mega cisterna magna 3 1 Blake pouch cyst 7 8 Dandy-Walker malformation 14 14 Inferior vermian hypoplasia 3 2 Total 100 100 Discussion Detailed descriptions of the taenia-tela choroidea complex (TTC) in the literature are inconsistent. The term tela, from the Latin "tēla," meaning "web" or “loom”, refers to a thin, weblike tissue layer. Despite its routine use in standard anatomical descriptions, the tela choroidea remains poorly characterized. Its architecture has been variably described, ranging from a pure epithelial layer to a double fold of pia mater, a non-pial connective tissue structure or a combination of pia mater, epithelium and associated vasculature. Functionally, it has been described as either a passive component of the ventricular roof or an active contributor to choroid plexus development [ 1 ]. Developmentally, the plica choroidalis becomes discernible around post-conception week 7 as an indentation between the anterior and posterior membranous areas [ 10 ]. Histologic studies from Bayer and Altman’s atlases show that the posterior membranous area, initially lined by neuroepithelium, progressively attenuates, and by week 9 is reduced to a thin arachnoid layer without neuroepithelial lining [ 11 ]. The history of Dandy-Walker malformation (DWM) is a complex one, marked by evolving definitions and ongoing debate. Historically, it was attributed to congenital atresia of the foramina of Luschka and Magendie, leading to cystic dilation of the fourth ventricle and secondary cerebellar hypoplasia [ 12 , 13 ]. Later, DWM was thought to derive from failure of regression of the area membranacea anterior [ 14 ]. Subsequent recognition of variable degrees of vermian hypoplasia and fourth ventricular expansion led to the concept of the Dandy-Walker spectrum [ 15 ]. The most recent developmental model, supported by analyses of human fetal tissue, suggests that DWM results from disrupted development of the rhombic lip [ 6 ]. The timing of this disruption is thought to determine the resulting malformation: early insults (before postconceptional 14 weeks) lead to severe vermian underdevelopment with an obtuse fastigial angle typical of DWM, whereas later insults result in milder vermian hypoplasia. The underlying cause remains unclear, with proposed mechanisms including genetic anomalies, prenatal environmental exposure and posthemorrhagic cerebellar injury [ 16 ]. At the mildest end of the spectrum, the status of Blake's pouch cyst (BPC) remains controversial, with ongoing debate as to whether it represents a distinct entity or falls within the same continuum [ 17 ]. Recent efforts to refine the imaging criteria for DWM identified the location of the TTC as a potential imaging biomarker for distinguishing DWM from BPC [ 4 ]. In normal anatomy of the TTC, the arachnoid separates into an outer layer forming the membranous roof of the fourth ventricular outflow and an inner layer continuous with the choroid plexus. In DWM, this delamination is absent, and the tela choroidea is thickened by apposition of its inner and outer layers. The choroid plexus along the inner arachnoid layer is similarly outstretched and attenuated. When intact, a point of separation between the two layers of arachnoid can still be seen near the obex. In all DWM cases in this cohort, we observed a lack of “internalization” of the rhombic lip, as previously described by Haldipur et al [ 18 ]. However, it appears that the abnormal development of the tela choroidea-choroid plexus complex is a constant feature as well. This suggests a possible role for the tela choroidea itself as a potential contributor to its pathogenesis. We can hypothesize that thickening and lack of fenestration of the tela could lead to fourth ventricular outlet obstruction, which may contribute to the variable degrees of posterior fossa enlargement seen in this spectrum. To complement these observations, we examined other posterior fossa malformations, with distinct pathogenesis, including Joubert syndrome [ 19 , 20 ] and Chiari 2 malformation. Despite the presence of significant vermian abnormalities, these cases also showed inferior displacement of the tela choroidea, but the inner and outer arachnoid layers remained distinct. This preliminary observation supports the specificity of membrane apposition to DWM, although a larger study is needed to confirm these findings. Inferolateral displacement of the choroid plexus has been reported as a feature of DWM [ 4 ]. As opposed to the previously reported findings on MRI, the utility of lateralization of the choroid plexus as a diagnostic marker of DWM in fetal autopsy appears limited. Although we observed a tendency toward lateral displacement of the choroid plexus in our pathology specimens, this finding should be interpreted with caution as the choroid plexus may be artifactually displaced during handling of the specimen as well. As such, this feature may be more robust on in vivo MRI when anatomical relationships are preserved. However, even on MRI, the diagnostic utility of this sign may be limited by the attenuated and outstretched configuration of the choroid plexus, which can make it less visible and more difficult to assess with confidence. Although no BPC specimens were available for histologic review in our series, Nelson et al. [ 14 ] reported that the BPC cyst wall contains ependyma, arachnoid, glial tissue and choroid plexus, consistent with its origin as an outpouching of the fourth ventricle. In the same series, the DWM cyst wall was described as containing all the same elements except choroid plexus. However, our observations in fetal studies showed no evidence of ependyma or glial tissue within the DWM cyst wall at midgestation; choroid plexus epithelium was present in all specimens. This would suggest failure in proper development of the posterior membranous area into the attenuated unilayered arachnoid at the late embryonic phase of development. While the pathogenesis of DWM remains unclear, we observed differences in the distribution of blood vessels in the TTC, suggestive of a possible role for vascular factors. In normal fetal specimens, the choroid plexus contains arborizing blood vessels, which are absent from the single layer of arachnoid comprising the membranous roof. In DWM, by contrast, blood vessels are present between the two layers of arachnoid in a simplified configuration, underlying the attenuated choroid plexus. Two of our cases exhibited hemosiderin-laden macrophages, possibly suggesting a role of early subarachnoid hemorrhage in the pathogenesis of DWM. Similar mechanism has been proposed in prior reports of posthemorrhagic cerebellar disruption [ 21 ]. On imaging, differentiating posterior fossa cystic malformations can be challenging, particularly in the prenatal period, with diagnostic criteria that have evolved over time and overlap between different entities [ 22 ]. Even the most recent imaging classification criteria acknowledge this ambiguity, noting overlap in tegmentovermian angle between DWM and BPC, vermian biometry between cerebellar vermian hypoplasia (CVH) and BPC [ 23 ], and including hybrid categories such as CVH with BPC [ 5 ]. Within this context, the rhombic lip hypothesis provides a unifying framework that DWM and CVH reflect different severities and timing of a common disruption. This perspective invites a shift away from rigid categorical labels toward a more spectrum-based framework, potentially prompting reconsideration of traditional nomenclature - including whether the term “Dandy-Walker” remains appropriate within a developmental continuum. Furthermore, the imaging features proposed for Dandy-Walker malformation are not unique and can overlap with other posterior fossa anomalies which are not encompassed in the imaging criteria such as Joubert syndrome, PHACES syndrome or pontocerebellar hypoplasia [ 24 ]. The status of BPC within the DWM continuum remains controversial, with ongoing debate as to whether it represents a separate entity. Although typically associated with more favorable neurodevelopmental outcomes, overlap in prognosis with DWM has been documented, underscoring the limitations of categorical distinctions. Imaging signs proposed to aid differentiation between these entities, such as the location of the TTC or lateral displacement of the choroid plexus [ 4 ], may be helpful in selected cases. However, we found visibility of the TTC is limited on routine prenatal MRI, even amongst experienced readers. In our series, the tela choroidea was confidently or borderline confidently visualized on prenatal MRI in only 53–72% of cases, with moderate interreader agreement. Choroid plexus visibility was lower, achieved only fair agreement. These rates are lower than those reported in a prior pediatric and prenatal study for TTC location (k = 0.73) and choroid plexus location (k = 0.85) between two readers [ 4 ]. The discrepancy may reflect differences in study design, including our prenatal-only cohort and use of a more granular scoring system which may have introduced greater variability. These findings highlight the challenges of consistently visualizing this delicate anatomic structure and suggest that its diagnostic utility seems constrained by technical factors and interreader variability. Thinner slices (≤ 3 mm) may improve TTC delineation. This study has the inherent limitations of a retrospective study. The number of adequate autopsy specimens was limited, and imaging data for pathology-radiology correlation was not obtainable across all cases. The diagnostic criteria for posterior fossa cystic malformations have evolved over time, which may have led to undersampling of cases due to variability in labeling. For example, some cases initially diagnosed as BPC would today be reclassified within the DWM spectrum. At our institution, when the cerebellum appeared normal, specimens were typically sampled using axial sections of the brainstem and cerebellum, causing potential underrepresentation of milder cases of DW spectrum in our cohort. The tela choroidea is a very delicate structure prone to rupture during sectioning, which complicates its detailed analysis, particularly in specimens that were reviewed retrospectively. Additionally, the specimens were processed using sagittal sectioning, which limited our ability to assess it in the other planes, and the variability in paramedian slicing across specimens limits reproducibility. Notably, no cases of BPC were available, as these are less likely to undergo termination of pregnancy and subsequent fetal autopsy. Conclusion The tela choroidea is a thin arachnoid membrane that normally delaminates along the inferior nodulus into an inner layer continuous with the choroid plexus and an outer layer forming the membranous roof of the fourth ventricular outflow. In Dandy-Walker malformation, these two layers fail to separate, resulting in a thickened, outstretched membranous roof lined by attenuated, inferiorly displaced choroid plexus epithelium. Such failure in tela delamination suggests a possible role of the tela choroidea itself in Dandy-Walker malformation pathogenesis. Impaired delamination and fenestration of the fourth ventricular outlet could result in obstruction and contribute to the variable degrees of posterior fossa enlargement. On prenatal MRI, tela visibility is variable, limiting its reliability as a diagnostic marker for posterior fossa cystic malformations. Further exploration of tela choroidea fenestration may represent a promising avenue for future investigations into posterior fossa cystic malformations. Declarations Author Contribution C.R. and Y.F. wrote the main manuscript text and prepared the figures. V.P., P.K., and E.M. performed the imaging review. Y.F. and P.S. performed the pathologic review. S.S. critically reviewed the manuscript. All authors reviewed and approved the final manuscript. 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Surg Neurol Int 5:112. https://doi.org/10.4103/2152-7806.137533 Haldipur P, Bernardo S, Aldinger KA et al (2021) Evidence of disrupted rhombic lip development in the pathogenesis of Dandy-Walker malformation. Acta Neuropathol 142:761–776. https://doi.org/10.1007/S00401-021-02355-7 Poretti A, Snow J, Summers AC et al (2017) Joubert syndrome: Neuroimaging findings in 110 patients in correlation with cognitive function and genetic cause. J Med Genet 54:521–529. https://doi.org/10.1136/JMEDGENET-2016-104425 Juric-Sekhar G, Adkins J, Doherty D, Hevner RF (2012) Joubert syndrome: Brain and spinal cord malformations in genotyped cases and implications for neurodevelopmental functions of primary cilia. Acta Neuropathol 123:695–709. https://doi.org/10.1007/S00401-012-0951-2 Limperopoulos C, Folkerth R, Barnewolt CE et al (2010) Posthemorrhagic Cerebellar Disruption Mimicking Dandy-Walker Malformation: Fetal Imaging and Neuropathology Findings. Semin Pediatr Neurol 17:75–81. https://doi.org/10.1016/J.SPEN.2010.02.015 Kau T, Marterer R, Kottke R et al (2020) Blakeʼs Pouch Cysts and Differential Diagnoses in Prenatal and Postnatal MRI: A Pictorial Review. Clin Neuroradiol 30:435–445. https://doi.org/10.1007/S00062-019-00871-4 Paladini D (2021) The hidden story of the fourth ventricular choroid plexus: the flower basket of an old anatomist… Ultrasound in. Obstet Gynecol 58:505–508. https://doi.org/10.1002/UOG.23726 Zakaria RBM, Malta M, Pelletier F et al (2024) Classic PCH Genes are a Rare Cause of Radiologic Pontocerebellar Hypoplasia. Cerebellum 23:418–430. https://doi.org/10.1007/S12311-023-01544-2 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7624319","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":516736693,"identity":"69a2be00-f2a8-457f-a881-f394150a43a2","order_by":0,"name":"Caroline Rutten","email":"","orcid":"","institution":"The Hospital for Sick Children","correspondingAuthor":false,"prefix":"","firstName":"Caroline","middleName":"","lastName":"Rutten","suffix":""},{"id":516736694,"identity":"74d14774-5461-4fc3-a218-7fd7a33ebf42","order_by":1,"name":"Yael Fisher","email":"","orcid":"","institution":"University of 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1","display":"","copyAsset":false,"role":"figure","size":1203375,"visible":true,"origin":"","legend":"\u003cp\u003eNormal tela choroidea at 22 weeks and 2 days’ gestation (ID 15).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Posterolateral macroscopic view of the brainstem and cerebellum. The tela choroidea, inked green, is a thin membrane that forms the thin inferior roof of the fourth ventricle outflow.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb\u003c/strong\u003e Mid-sagittal macroscopic view. Cranially, the tela choroidea is continuous with the arachnoid overlying the inferior vermis and caudally, it attaches along the inferolateral borders of the fourth ventricular outflow, at ridges known as taeniae, that converge at the obex. The choroid plexus is visible at the caudal opening of the fourth ventricle, between the cerebellum and dorsal brainstem (arrow).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ec\u003c/strong\u003e Histological mid-sagittal section. The membranous roof of the fourth ventricle outflow consists of a thin layer of arachnoid that delaminates into two layers at the inferior margin of the nodulus: an inner layer continuous with the choroid plexus and an outer layer forming the membranous roof that attaches to the taeniae (arrow).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ed\u003c/strong\u003e Medium-magnification mid-sagittal section through the fourth ventricle showing delamination of the tela choroidea into inner (arrowhead) and outer (arrow) layers near the ventral-inferior margin of the cerebellum.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ee \u003c/strong\u003eHigh-magnification mid-sagittal section of the tela choroidea near the taenia highlights its normal unilaminar configuration (the dark green pigment represents the ink seen in macroscopic images).\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-7624319/v1/cf62ca2d45a0851416bfb8d1.png"},{"id":92194611,"identity":"81b0becf-c671-4735-96f9-6b22e0bdccf5","added_by":"auto","created_at":"2025-09-25 15:39:57","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1426460,"visible":true,"origin":"","legend":"\u003cp\u003eAbnormal tela choroidea in Dandy-Walker malformation at 24 weeks’ gestation (ID 7).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Mid-sagittal T2-weighted fetal MRI demonstrates hallmark features of Dandy-Walker malformation, including inferior-predominant vermian hypoplasia with an obtuse fastigial angle, a tail sign, an enlarged tegmentovermian angle and a dilated fourth ventricle within a moderately enlarged posterior fossa.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb, c\u003c/strong\u003e Mid-sagittal macroscopic (b) and histological (c) sections through the brainstem and cerebellum show a hypoplastic vermis, with a blunted, obtuse fastigial angle (b, arrowhead). The tail sign corresponds to a partially formed posterior lobule attached, continuous with an inferiorly displaced germinal trigone (b, c, black arrow). The tela choroidea appears thickened (b, white arrow), composed of a double-layered arachnoid and attenuated choroid plexus.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ed\u003c/strong\u003e Medium-magnification mid-sagittal section demonstrates a bilaminar configuration of the tela choroidea. The membranes are negative for GFAP immunostaining, confirming the absence of astroglial elements within the membrane.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ee\u003c/strong\u003e High-magnification mid-sagittal section of the abnormally bilaminated tela choroidea. Nestin immunohistochemical stain highlights the endothelium of blood vessels between the two layers of arachnoid (arrowhead).\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-7624319/v1/96e6b5ed2e6e711decffefa8.png"},{"id":92194612,"identity":"0a92e3a4-8cf7-422d-a9c9-c9833386816e","added_by":"auto","created_at":"2025-09-25 15:39:57","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":3986285,"visible":true,"origin":"","legend":"\u003cp\u003eAbnormal tela choroidea in Dandy-Walker malformation at 20 weeks’ gestation (ID 1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Mid-sagittal T2-weighted fetal MRI shows characteristic features of Dandy-Walker malformation, including inferior-predominant vermian hypoplasia with an obtuse fastigial angle, an enlarged tegmentovermian angle and a dilated fourth ventricle within a moderately enlarged posterior fossa. No tail sign is identified.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb\u003c/strong\u003e Macroscopic view of the posterior fossa showing inferolateral displacement of the choroid plexus (arrowheads)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ec\u003c/strong\u003e Macroscopic mid-sagittal section through the brainstem and cerebellum. The vermis is hypoplastic and superiorly rotated, with an almost flattened fastigial angle (arrowhead). The tela choroidea appears thickened (white arrow), similar to Fig. 2.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ed\u003c/strong\u003e Mid-sagittal histological section. The tela choroidea is detached from the dorsal brainstem and extends from the germinal trigone, overlaid by attenuated choroid plexus (arrow).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ee\u003c/strong\u003e Paramedian sagittal section through the lateral recess of the fourth ventricle. A prominent bulk of choroid plexus is located along the inferior ventral margin of the cerebellum (arrow), with smaller bulks (arrowheads) distributed along the outstretched cyst wall.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-7624319/v1/8ae37bec3f6b1b6dae9be269.png"},{"id":92194620,"identity":"d781e601-1c01-427c-ac43-252e8889f8fb","added_by":"auto","created_at":"2025-09-25 15:39:57","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":3621150,"visible":true,"origin":"","legend":"\u003cp\u003eAbnormal tela choroidea in Dandy-Walker malformation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea, b, c\u003c/strong\u003e Macroscopic view of the posterior fossa, mid-sagittal histological section and high-magnification mid-sagittal section of the tela choroidea with cytokeratin staining in a fetus at 23 + 4 weeks’ gestation (ID 5). The vermis is dysplastic with a large fourth ventricular opening and inferiorly displaced choroid plexus (a, arrows). The mid-sagittal histological section shows an outstretched tela (b, arrow). Near the obex, there is a short segment of single-layered arachnoid, unlined by choroid plexus, followed by a small bulk of choroid plexus (c, arrow).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ed, e, f\u003c/strong\u003e Macroscopic view of the posterior fossa, midsagittal histological section and high-magnification sagittal section of the tela choroidea in a fetus at 23 weeks’ gestation (ID 8). An organising subarachnoid hemorrhage overlies the right cerebellar hemisphere and vermis (d, black arrow). The tela choroidea is thick and irregular (d, white arrows) and the choroid plexus is visibly displaced inferiorly (e, arrowhead). Hemosiderin-laden macrophages are seen along the tela choroidea, between the arachnoid layers (f, arrows).\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-7624319/v1/de4d55b4bd210b623c884b58.png"},{"id":92195230,"identity":"36e0f53d-5d8c-4e99-9327-33af17596d20","added_by":"auto","created_at":"2025-09-25 15:47:57","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1114728,"visible":true,"origin":"","legend":"\u003cp\u003eTela choroidea in Joubert syndrome at 23 weeks’ gestation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Sagittal T2-weighted fetal MRI demonstrates characteristic features of Joubert syndrome, including a dysplastic vermis and thickened, horizontally oriented superior cerebellar peduncles. The tegmentovermian angle is enlarged and the fourth ventricle dilated within a moderately enlarged posterior fossa.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb \u003c/strong\u003ePosterior macroscopic view of the brainstem and cerebellum showing an enlarged opening of the fourth ventricle covered by a thin and transparent tela choroidea. The choroid plexus (arrows) is observed along the cerebellar hemispheres.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ec\u003c/strong\u003e Mid-sagittal macroscopic section through the brainstem and cerebellum showing vermian dysplasia at both anterior and posterior parts. The choroid plexus is visible at the caudal aspect of the fourth ventricle (arrow).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ed, e\u003c/strong\u003e Midsagittal histological sections show an intact tela choroidea with normal delamination into two distinct layers: an inner layer continuous with the choroid plexus and a thin outer layer (d, e, arrow) forming the membranous roof of the fourth ventricular outflow.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-7624319/v1/87845b80b2672abf8fdd56d4.png"},{"id":92194621,"identity":"54e17c93-69de-4b05-b494-3510c7f027de","added_by":"auto","created_at":"2025-09-25 15:39:57","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":977478,"visible":true,"origin":"","legend":"\u003cp\u003eTela choroidea in Chiari 2 malformation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Mid-sagittal T2-weighted fetal MRI at 27 weeks’ gestation demonstrates characteristic features of Chiari 2 malformation, including a small posterior fossa with caudal displacement of the cerebellum and lower brainstem into the upper cervical spinal canal. The tentorium has a low insertion and there is crowding of the neural structures at the level of the foramen magnum and upper cervical spine. The fourth ventricle, fastigial point and primary fissures are effaced, and the cisterna magna is obliterated.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb\u003c/strong\u003e Macroscopic posterior view of the posterior fossa in a different fetus at 25 weeks’ gestation. The vermis is herniated through the foramen magnum. The choroid plexus at the opening of the fourth ventricle appears congested (arrows).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ec, d \u003c/strong\u003eMid-sagittal histological sections through the brainstem and cerebellum demonstrate inferior displacement of the tela choroidea and choroid plexus (c, arrow). The tela retains a normal architecture with a clear separation between the choroid plexus and the single-layered arachnoid forming the membranous roof of the fourth ventricular outflow (d, arrow).\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-7624319/v1/c3fc39460c08236d56c908f7.png"},{"id":93157899,"identity":"c4262674-13e2-489c-b505-466bf6d84d51","added_by":"auto","created_at":"2025-10-09 15:53:51","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":16599584,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7624319/v1/f68cafa0-80d0-4108-a16f-f003f878dc44.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The Fetal Taenia–Tela Choroidea Complex: A Radiologic–Pathologic Correlation from Normal Anatomy to Dandy-Walker Malformation","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe taenia-tela choroidea complex (TTC) has been described inconsistently across the literature, leading to potential confusion [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Recently, its anatomical location has emerged as a potentially valuable imaging marker to differentiate Dandy-Walker malformation (DWM) from Blake\u0026rsquo;s pouch cyst (BPC) on prenatal ultrasound [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] and MRI [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The most recent imaging criteria for DWM include inferior-predominant vermian hypoplasia, an obtuse fastigial recess, an enlarged tegmentovermian angle, the tail sign (inconstant) and inferolateral displacement of the TTC and choroid plexus away from the vermis, while posterior fossa size and torcular location have been excluded [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. In contrast, BPC is characterized by a normal-sized vermis, an enlarged tegmentovermian angle and TTC/choroid plexus positioned along the inferomedial cerebellar margin.\u003c/p\u003e\u003cp\u003eThe prognosis of DWM is highly variable, ranging from normal development to severe disability. Poor outcomes are more likely in the presence of additional central nervous system anomalies, hydrocephalus, severe vermian hypoplasia or an underlying genetic diagnosis. In contrast, BPC is generally considered benign, with a favourable neurodevelopmental outcome [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Prenatal distinction between these entities can be challenging. There is considerable phenotypical overlap, and mild structural abnormalities can be subtle. BPC can skew vermian height measurements, tegmentovermian angles can overlap between entities and fastigial recess assessment can be very challenging in the second trimester.\u003c/p\u003e\u003cp\u003eThe ability to distinguish these malformations early in gestation significantly impacts prognosis counseling. Despite its imaging promise, the tela choroidea remains poorly characterized and comprehensive studies correlating radiological findings with pathological examination are limited. Advancements in fetal MRI have greatly improved our ability to visualize complex neuroanatomy. However, identifying smaller, delicate structures such as the tela choroidea can remain technically challenging. Factors such as gestational age, image resolution, and motion artifacts can influence the detectability and reliability of these anatomical components in clinical practice. Given the proposed significance of the TTC/choroid plexus location in distinguishing posterior fossa malformations, a thorough investigation into the visibility and consistency of these markers on routine prenatal MRI seems warranted.\u003c/p\u003e\u003cp\u003eThis study had two main objectives. The first was to examine the histology and pathology-radiology correlation of the TTC in the normal fetal posterior fossa and in DWM. The second was to evaluate how consistently the TTC can be visualized on routine prenatal MRI, as interpreted by experienced fetal radiologists. By addressing these objectives, the study aims to improve our understanding of the normal TTC, clarify its morphological characteristics and discuss its diagnostic value in fetal posterior fossa malformations.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eThis retrospective study was approved by the institutional ethics board (REB #1000080667, REB # 80667), with a waiver of informed consent.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eHistology and Radiologic-Pathologic Correlation of the Tela Choroidea-Choroid Plexus Complex\u003c/h2\u003e\u003cp\u003eCases of Dandy-Walker spectrum malformations were identified from fetal autopsy archives (2007\u0026ndash;2024) using keyword searches for \u0026ldquo;Dandy-Walker\u0026rdquo; and \u0026ldquo;Blake\u0026rsquo;s Pouch Cyst\u0026rdquo;. Cases with complex central nervous system malformations or lacking high-quality sagittal sections of the brainstem and cerebellum were excluded. A few cases initially diagnosed as BPC on prenatal ultrasound were excluded because macroscopic examination demonstrated a normal cerebellum and the brainstem and cerebellum had been sectioned in the axial plane.\u003c/p\u003e\u003cp\u003eA control group of normal cases was established by selecting consecutive age-matched specimens with an intact brainstem and cerebellum, and a visible membranous roof of the fourth ventricular outflow. Specimens were inked, sectioned in the sagittal plane, and photographed. To assess whether our findings were specific to DWM, we also searched for other posterior fossa malformations involving the cerebellar vermis using the keywords \u0026ldquo;Chiari\u0026rdquo; and \u0026ldquo;Joubert\u0026rdquo;. Cases were included if midsagittal sections of the brainstem and cerebellum were available and the TTC remained intact.\u003c/p\u003e\u003cp\u003eThe following variables were extracted from pathology reports: gestational age, fetal sex and results of genetic testing when available. All included specimens were reviewed for the following features: location and distribution of the choroid plexus (midline to dentate, at level of dentate and paramedian to dentate), integrity of the tela choroidea (ruptured vs. intact), spatial relationship between the tela choroidea and the inferior medullary velum, lamination pattern of the tela choroidea (unilaminar vs. bilaminar), and morphology of the cerebellum and fastigium. Selected specimens underwent immunohistochemical staining with antibodies to nestin (polyclonal), glial fibrillary acidic protein (GFAP), and cytokeratin. Availability of fetal MRI was recorded, and radiologic-pathologic correlation was performed when imaging was available.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eFetal MRI Study Population\u003c/h3\u003e\n\u003cp\u003eA sample size of 96 MRI cases was calculated based on an estimated 50% visibility rate of the tela choroidea, with 80% power and a 5% significance level. To identify eligible cases, 972 fetal neuroimaging MRI reports between May 2018 and February 2025 were screened.\u003c/p\u003e\u003cp\u003eCases of normal posterior fossa were included, defined by age-appropriate cerebellar and vermian biometry and morphology with a tegmento-vermian angle\u0026thinsp;\u0026lt;\u0026thinsp;8\u0026deg;. Cases of posterior fossa cystic malformation included DWM, BPC, inferior vermian hypoplasia and mega cisterna magna. Cases were excluded if they demonstrated posterior fossa abnormalities outside the DWM spectrum (Chiari 2 malformation, rhombencephalosynapsis, Joubert syndrome, posterior fossa arachnoid cyst), supratentorial anomalies or significant motion degradation precluding reliable posterior fossa assessment.\u003c/p\u003e\u003cp\u003eTwo pediatric neuroradiologists (P.K., 10 years post-fellowship experience, E.M., 20 years post-fellowship experience) blinded to initial interpretations independently evaluated the MRI studies using a standardized reading grid. They assessed two parameters: visibility of the tela choroidea and the fourth ventricular choroid plexus on T2-weighted images across all 3 orthogonal planes. Visibility was scored on a standardized three-point scale: confident, borderline confident or not confident/not visible.\u003c/p\u003e\n\u003ch3\u003eFetal MRI protocol\u003c/h3\u003e\n\u003cdiv class=\"Heading\"\u003eFetal MRI protocol\u003c/div\u003e\u003cp\u003eOur institutional protocol is as follows: sagittal, coronal and axial single-shot fast spin-echo T2-weighted images (repetition time/echo time [TR/TE]: 1500/177 ms; 3\u0026ndash;4-mm slice thickness); axial T1 SNAP (repetition time/echo time [TR/TE]: 9500/5.3 ms; inversion time [TI]: 200 ms; 5.0-mm slice thickness); axial diffusion-weighted images (repetition time/echo time [TR/TE]: 3200/60 ms; 5.0-mm slice thickness); axial susceptibility-weighted images (TR/TE: 143/19.8 ms; 5-mm slice thickness). Images were acquired on a 1.5T MAGNETOM Avanto Fit or 3.0T MAGNETOM Skyra (Siemens Healthcare, Erlangen, Germany).\u003c/p\u003e\n\u003ch3\u003eStatistics\u003c/h3\u003e\n\u003cp\u003eBaseline characteristics were summarized using descriptive statistics: categorical data using counts and percentages and continuous data using median and range. The interreader agreement for MRI findings among the two readers was assessed using weighted Cohen\u0026rsquo;s kappa statistic, with interpretation as follows: κ\u0026thinsp;\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u0026le;\u003c/span\u003e\u0026thinsp;0.20, poor; \u0026gt;0.20 and \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u0026le;\u003c/span\u003e\u0026thinsp;0.40, fair; \u0026gt;0.40 and \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u0026le;\u003c/span\u003e\u0026thinsp;0.60, moderate; \u0026gt;0.60 and \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e\u0026le;\u003c/span\u003e\u0026thinsp;0.80, good; \u0026gt;0.80 excellent [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Statistical analyses were performed using Excel software version 16.95.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003ePathologic examination\u003c/h2\u003e\u003cdiv id=\"Sec9\" class=\"Section3\"\u003e\u003ch2\u003eStudy Population\u003c/h2\u003e\u003cp\u003eTwelve autopsy cases of DWM were identified through keyword search. Three cases were excluded for technical quality or complex malformations, leaving a total of nine DWM pathology specimens (gestational age 20\u0026ndash;24 weeks) with MRI correlation available for five. Two specimens were siblings (ID 2 and 6).\u003c/p\u003e\u003cp\u003eThe control group included eight age-matched normal posterior fossa controls (gestational age 21\u0026ndash;24 weeks) with MRI correlation available for one. Histologic features of the tela choroidea and choroid plexus differed between groups (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCharacteristics of the study population, including histologic features of the tela choroidea and choroid plexus. The choroid plexus columns (\u0026ldquo;Medial to dentate,\u0026rdquo; \u0026ldquo;At dentate,\u0026rdquo; \u0026ldquo;Lateral to dentate\u0026rdquo;) indicate the location of the choroid plexus bulk relative to the dentate nucleus. MRI availability is indicated. Patients 2 and 6 are siblings. Abbreviations: DW\u0026thinsp;=\u0026thinsp;Dandy\u0026ndash;Walker malformation; N\u0026thinsp;=\u0026thinsp;normal posterior fossa; GA\u0026thinsp;=\u0026thinsp;gestational age in weeks; M\u0026thinsp;=\u0026thinsp;male; F\u0026thinsp;=\u0026thinsp;female; IMV\u0026thinsp;=\u0026thinsp;inferior medullary velum; MRI\u0026thinsp;=\u0026thinsp;magnetic resonance imaging; NA\u0026thinsp;=\u0026thinsp;not available\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"14\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eID\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGroup\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eGA\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSex\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eChoroid plexus\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTela choroidea\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eRelationship to IMV\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eLamination\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eCerebellum\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eFastigium\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eMedial to dentate\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u003cp\u003eAt dentate\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c13\"\u003e\u003cp\u003eLateral to dentate\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c14\"\u003e\u003cp\u003eMRI\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eInferiorly displaced\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eBilaminar\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eHypoplastic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eBlunted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eLarger bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eInferiorly displaced\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eOutstretched\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eBilaminar\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eHypoplastic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eObtuse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eLarger bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eInferiorly displaced\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eHypoplastic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eBlunted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eLarge bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eInferiorly displaced\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eOutstretched\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eHypoplastic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eObtuse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eTrace\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23\u0026thinsp;+\u0026thinsp;4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eInferiorly displaced\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eBilaminar\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eHypoplastic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eObtuse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23\u0026thinsp;+\u0026thinsp;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eInferiorly displaced\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eOutstretched\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eHypoplastic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eObtuse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eMinute bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eInferiorly displaced\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eOutstretched\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eBilaminar\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eHypoplastic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eObtuse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eLarger bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eInferiorly displaced\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eOutstretched\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eBilaminar\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eHypoplastic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eObtuse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eInferiorly displaced\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eBilaminar\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eHypoplastic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eBlunted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eLarger bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eDelaminated roof\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eLarger bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21\u0026thinsp;+\u0026thinsp;4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eDelaminated roof\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eLarger bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eLarge bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eLarge bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e22\u0026thinsp;+\u0026thinsp;2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e22\u0026thinsp;+\u0026thinsp;2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eDelaminated roof\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eLarge bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eSmall bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eLarger bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRuptured\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eIntact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eDelaminated roof\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eLarge bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003eLarge bulk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\n\u003ch3\u003eNormal tela choroidea-choroid plexus complex\u003c/h3\u003e\n\u003cp\u003eIn all eight normal posterior fossa fetal specimens, the germinal trigone was located within the fourth ventricle, immediately adjacent to the choroid plexus. The tela choroidea was intact in 2/8 cases and detached in the remaining 6/8 cases.\u003c/p\u003e\u003cp\u003eHistologically, the tela was continuous with the overlying arachnoid of the vermis. We identified a separation between the two layers of arachnoid at the ventrocaudal aspect of the inferior vermis (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The inner layer extended under the inferior vermis and supported the choroid plexus, whereas the outer layer formed the membranous roof of the fourth ventricular outflow, attaching to the taenia and converging at the obex. Immunohistochemical stains for GFAP, cytokeratin and nestin confirmed the absence of glial, neuroepithelial and endothelial cells in the membranous roof, consistent with a composition of a single meningeal layer. The choroid plexus, continuous with the inner layer of arachnoid was located in the fourth ventricle adjacent to the inferior medullary velum, extending to the ventro-caudal aspect of the vermis. In most cases, the largest choroid plexus bulk was located medial to, or at the level of the dentate nucleus, with one exception where the largest bulk was seen lateral to the dentate nucleus.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eTela choroidea-choroid plexus complex in Dandy-Walker malformation\u003c/h2\u003e\u003cp\u003eMacroscopic images of the Dandy-Walker cyst were available for six cases. These all showed inferior displacement of the tela choroidea and choroid plexus (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). On histology, the tela choroidea was outstretched and thickened by apposition of the inner and outer layers of arachnoid. Embryonic capillaries, positive for nestin immunohistochemical stain, were present in between the double layer of arachnoid [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. This double-layered membrane was lined by choroid plexus epithelium (i.e. a ciliated cuboidal epithelium, cytokeratin positive, GFAP negative, continuous with fronds of choroid plexus) facing towards the fourth ventricle, with the main bulk attenuated, outstretched and laterally displaced.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eIn two cases (ID 8 and 9), hemosiderin-laden macrophages were seen along the tela choroidea, between the arachnoid layers and within the choroid plexus. In one of these, there was evidence of an organising subarachnoid hemorrhage over the posteroinferior cerebellar vermis, without underlying cortical injury, likely dating to the early second trimester (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eRadiologic-pathologic correlation\u003c/h2\u003e\u003cp\u003eMRI correlation was available for 6/15 cases (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Although the tela choroidea was not visible on MRI for these cases, inferolateral displacement of the choroid plexus was consistently noted in cases of DWM.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eTela choroidea in other posterior fossa malformations\u003c/h2\u003e\u003cp\u003eSeven cases with other brainstem malformations were identified, four with Chiari 2 malformation and three with Joubert syndrome. Macroscopically, when the tela choroidea was visible, it was along the cerebellar hemispheres. The tela choroidea was inferiorly displaced, similar to DWM; however, the lamination was normal with separation between the two layers of arachnoid (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003eMRI reading\u003c/h2\u003e\u003cp\u003eA total of 100 fetal MRIs were included, with gestational ages ranging from 21\u0026thinsp;+\u0026thinsp;2 to 38\u0026thinsp;+\u0026thinsp;1 weeks (median 29.5 weeks). The tela was rated as confidently visible on T2-weighted images in 28\u0026ndash;33% of cases, and as either confident or borderline confident in 53\u0026ndash;72% (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Interobserver agreement was moderate (κ\u0026thinsp;=\u0026thinsp;0.49). On gradient-echo images, the tela choroidea was only visible in 12\u0026ndash;20% of cases, with poor agreement between readers (κ\u0026thinsp;=\u0026thinsp;0.19). The choroid plexus was rated as confidently visible in 23\u0026ndash;30% of cases, with fair agreement (κ\u0026thinsp;=\u0026thinsp;0.27). When asked whether the orientation of the taenia\u0026ndash;tela choroidea complex aided diagnosis or differentiation of BPC from DWM, one reader found it useful in a single case, and the other in none. Agreement for final diagnostic categorization was excellent across both readers.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eInterobserver agreement for tela choroidea and choroid plexus visibility on prenatal MRI. Data are presented as number of cases per category for each reader with Cohen\u0026rsquo;s kappa values indicating agreement. Abbreviations: CI\u0026thinsp;=\u0026thinsp;confidence interval; TTC\u0026thinsp;=\u0026thinsp;Taenia-tela choroidea complex\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eItem\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCategory\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eReader 1 (n)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eReader 2 (n)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eWeighted k (95% CI)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eTela Choroidea Visibility on T2-weighted images\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eConfident\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.49 (0.34\u0026ndash;0.62)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBorderline confident\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNot confident / Not visible\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTela Choroidea Visibility on gradient echo images\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVisible\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.19 (-0.04-0.42)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNot visible\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eChoroid Plexus Visibility\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eConfident\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.27 (0.10\u0026ndash;0.44)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBorderline confident\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNot confident / Not visible\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eUsefulness of TTC orientation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e\u003cp\u003eFinal diagnosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNormal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.83 (0.74\u0026ndash;0.94)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMega cisterna magna\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBlake pouch cyst\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDandy-Walker malformation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInferior vermian hypoplasia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eTotal\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eDetailed descriptions of the taenia-tela choroidea complex (TTC) in the literature are inconsistent. The term tela, from the Latin \"tēla,\" meaning \"web\" or \u0026ldquo;loom\u0026rdquo;, refers to a thin, weblike tissue layer. Despite its routine use in standard anatomical descriptions, the tela choroidea remains poorly characterized. Its architecture has been variably described, ranging from a pure epithelial layer to a double fold of pia mater, a non-pial connective tissue structure or a combination of pia mater, epithelium and associated vasculature. Functionally, it has been described as either a passive component of the ventricular roof or an active contributor to choroid plexus development [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Developmentally, the plica choroidalis becomes discernible around post-conception week 7 as an indentation between the anterior and posterior membranous areas [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Histologic studies from Bayer and Altman\u0026rsquo;s atlases show that the posterior membranous area, initially lined by neuroepithelium, progressively attenuates, and by week 9 is reduced to a thin arachnoid layer without neuroepithelial lining [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe history of Dandy-Walker malformation (DWM) is a complex one, marked by evolving definitions and ongoing debate. Historically, it was attributed to congenital atresia of the foramina of Luschka and Magendie, leading to cystic dilation of the fourth ventricle and secondary cerebellar hypoplasia [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Later, DWM was thought to derive from failure of regression of the area membranacea anterior [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Subsequent recognition of variable degrees of vermian hypoplasia and fourth ventricular expansion led to the concept of the Dandy-Walker spectrum [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The most recent developmental model, supported by analyses of human fetal tissue, suggests that DWM results from disrupted development of the rhombic lip [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The timing of this disruption is thought to determine the resulting malformation: early insults (before postconceptional 14 weeks) lead to severe vermian underdevelopment with an obtuse fastigial angle typical of DWM, whereas later insults result in milder vermian hypoplasia. The underlying cause remains unclear, with proposed mechanisms including genetic anomalies, prenatal environmental exposure and posthemorrhagic cerebellar injury [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. At the mildest end of the spectrum, the status of Blake's pouch cyst (BPC) remains controversial, with ongoing debate as to whether it represents a distinct entity or falls within the same continuum [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Recent efforts to refine the imaging criteria for DWM identified the location of the TTC as a potential imaging biomarker for distinguishing DWM from BPC [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn normal anatomy of the TTC, the arachnoid separates into an outer layer forming the membranous roof of the fourth ventricular outflow and an inner layer continuous with the choroid plexus. In DWM, this delamination is absent, and the tela choroidea is thickened by apposition of its inner and outer layers. The choroid plexus along the inner arachnoid layer is similarly outstretched and attenuated. When intact, a point of separation between the two layers of arachnoid can still be seen near the obex. In all DWM cases in this cohort, we observed a lack of \u0026ldquo;internalization\u0026rdquo; of the rhombic lip, as previously described by Haldipur et al [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. However, it appears that the abnormal development of the tela choroidea-choroid plexus complex is a constant feature as well. This suggests a possible role for the tela choroidea itself as a potential contributor to its pathogenesis. We can hypothesize that thickening and lack of fenestration of the tela could lead to fourth ventricular outlet obstruction, which may contribute to the variable degrees of posterior fossa enlargement seen in this spectrum.\u003c/p\u003e\u003cp\u003eTo complement these observations, we examined other posterior fossa malformations, with distinct pathogenesis, including Joubert syndrome [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] and Chiari 2 malformation. Despite the presence of significant vermian abnormalities, these cases also showed inferior displacement of the tela choroidea, but the inner and outer arachnoid layers remained distinct. This preliminary observation supports the specificity of membrane apposition to DWM, although a larger study is needed to confirm these findings.\u003c/p\u003e\u003cp\u003eInferolateral displacement of the choroid plexus has been reported as a feature of DWM [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. As opposed to the previously reported findings on MRI, the utility of lateralization of the choroid plexus as a diagnostic marker of DWM in fetal autopsy appears limited. Although we observed a tendency toward lateral displacement of the choroid plexus in our pathology specimens, this finding should be interpreted with caution as the choroid plexus may be artifactually displaced during handling of the specimen as well. As such, this feature may be more robust on in vivo MRI when anatomical relationships are preserved. However, even on MRI, the diagnostic utility of this sign may be limited by the attenuated and outstretched configuration of the choroid plexus, which can make it less visible and more difficult to assess with confidence.\u003c/p\u003e\u003cp\u003eAlthough no BPC specimens were available for histologic review in our series, Nelson et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] reported that the BPC cyst wall contains ependyma, arachnoid, glial tissue and choroid plexus, consistent with its origin as an outpouching of the fourth ventricle. In the same series, the DWM cyst wall was described as containing all the same elements except choroid plexus. However, our observations in fetal studies showed no evidence of ependyma or glial tissue within the DWM cyst wall at midgestation; choroid plexus epithelium was present in all specimens. This would suggest failure in proper development of the posterior membranous area into the attenuated unilayered arachnoid at the late embryonic phase of development.\u003c/p\u003e\u003cp\u003eWhile the pathogenesis of DWM remains unclear, we observed differences in the distribution of blood vessels in the TTC, suggestive of a possible role for vascular factors. In normal fetal specimens, the choroid plexus contains arborizing blood vessels, which are absent from the single layer of arachnoid comprising the membranous roof. In DWM, by contrast, blood vessels are present between the two layers of arachnoid in a simplified configuration, underlying the attenuated choroid plexus. Two of our cases exhibited hemosiderin-laden macrophages, possibly suggesting a role of early subarachnoid hemorrhage in the pathogenesis of DWM. Similar mechanism has been proposed in prior reports of posthemorrhagic cerebellar disruption [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eOn imaging, differentiating posterior fossa cystic malformations can be challenging, particularly in the prenatal period, with diagnostic criteria that have evolved over time and overlap between different entities [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Even the most recent imaging classification criteria acknowledge this ambiguity, noting overlap in tegmentovermian angle between DWM and BPC, vermian biometry between cerebellar vermian hypoplasia (CVH) and BPC [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], and including hybrid categories such as CVH with BPC [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Within this context, the rhombic lip hypothesis provides a unifying framework that DWM and CVH reflect different severities and timing of a common disruption. This perspective invites a shift away from rigid categorical labels toward a more spectrum-based framework, potentially prompting reconsideration of traditional nomenclature - including whether the term \u0026ldquo;Dandy-Walker\u0026rdquo; remains appropriate within a developmental continuum. Furthermore, the imaging features proposed for Dandy-Walker malformation are not unique and can overlap with other posterior fossa anomalies which are not encompassed in the imaging criteria such as Joubert syndrome, PHACES syndrome or pontocerebellar hypoplasia [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe status of BPC within the DWM continuum remains controversial, with ongoing debate as to whether it represents a separate entity. Although typically associated with more favorable neurodevelopmental outcomes, overlap in prognosis with DWM has been documented, underscoring the limitations of categorical distinctions. Imaging signs proposed to aid differentiation between these entities, such as the location of the TTC or lateral displacement of the choroid plexus [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], may be helpful in selected cases. However, we found visibility of the TTC is limited on routine prenatal MRI, even amongst experienced readers.\u003c/p\u003e\u003cp\u003eIn our series, the tela choroidea was confidently or borderline confidently visualized on prenatal MRI in only 53\u0026ndash;72% of cases, with moderate interreader agreement. Choroid plexus visibility was lower, achieved only fair agreement. These rates are lower than those reported in a prior pediatric and prenatal study for TTC location (k\u0026thinsp;=\u0026thinsp;0.73) and choroid plexus location (k\u0026thinsp;=\u0026thinsp;0.85) between two readers [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The discrepancy may reflect differences in study design, including our prenatal-only cohort and use of a more granular scoring system which may have introduced greater variability. These findings highlight the challenges of consistently visualizing this delicate anatomic structure and suggest that its diagnostic utility seems constrained by technical factors and interreader variability. Thinner slices (\u0026le;\u0026thinsp;3 mm) may improve TTC delineation.\u003c/p\u003e\u003cp\u003eThis study has the inherent limitations of a retrospective study. The number of adequate autopsy specimens was limited, and imaging data for pathology-radiology correlation was not obtainable across all cases. The diagnostic criteria for posterior fossa cystic malformations have evolved over time, which may have led to undersampling of cases due to variability in labeling. For example, some cases initially diagnosed as BPC would today be reclassified within the DWM spectrum. At our institution, when the cerebellum appeared normal, specimens were typically sampled using axial sections of the brainstem and cerebellum, causing potential underrepresentation of milder cases of DW spectrum in our cohort. The tela choroidea is a very delicate structure prone to rupture during sectioning, which complicates its detailed analysis, particularly in specimens that were reviewed retrospectively. Additionally, the specimens were processed using sagittal sectioning, which limited our ability to assess it in the other planes, and the variability in paramedian slicing across specimens limits reproducibility. Notably, no cases of BPC were available, as these are less likely to undergo termination of pregnancy and subsequent fetal autopsy.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe tela choroidea is a thin arachnoid membrane that normally delaminates along the inferior nodulus into an inner layer continuous with the choroid plexus and an outer layer forming the membranous roof of the fourth ventricular outflow. In Dandy-Walker malformation, these two layers fail to separate, resulting in a thickened, outstretched membranous roof lined by attenuated, inferiorly displaced choroid plexus epithelium. Such failure in tela delamination suggests a possible role of the tela choroidea itself in Dandy-Walker malformation pathogenesis. Impaired delamination and fenestration of the fourth ventricular outlet could result in obstruction and contribute to the variable degrees of posterior fossa enlargement. On prenatal MRI, tela visibility is variable, limiting its reliability as a diagnostic marker for posterior fossa cystic malformations. Further exploration of tela choroidea fenestration may represent a promising avenue for future investigations into posterior fossa cystic malformations.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eC.R. and Y.F. wrote the main manuscript text and prepared the figures. V.P., P.K., and E.M. performed the imaging review. Y.F. and P.S. performed the pathologic review. S.S. critically reviewed the manuscript. All authors reviewed and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eKoellmberger M, Witter K (2024) Use and meaning of the anatomical terms Plexus choroideus and Tela choroidea in veterinary and human medicine. Folia Morphol (Warsz) 83:757\u0026ndash;770. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5603/FM.98803\u003c/span\u003e\u003cspan address=\"10.5603/FM.98803\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePaladini D, Donarini G, Parodi S et al (2019) Hindbrain morphometry and choroid plexus position in differential diagnosis of posterior fossa cystic malformations. 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Clin Neuroradiol 30:435\u0026ndash;445. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/S00062-019-00871-4\u003c/span\u003e\u003cspan address=\"10.1007/S00062-019-00871-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePaladini D (2021) The hidden story of the fourth ventricular choroid plexus: the flower basket of an old anatomist\u0026hellip; Ultrasound in. Obstet Gynecol 58:505\u0026ndash;508. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/UOG.23726\u003c/span\u003e\u003cspan address=\"10.1002/UOG.23726\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZakaria RBM, Malta M, Pelletier F et al (2024) Classic PCH Genes are a Rare Cause of Radiologic Pontocerebellar Hypoplasia. Cerebellum 23:418\u0026ndash;430. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/S12311-023-01544-2\u003c/span\u003e\u003cspan address=\"10.1007/S12311-023-01544-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Choroid Plexus, Dandy-Walker malformation, Magnetic Resonance Imaging, Neuroanatomy, Prenatal Diagnosis, Tela choroidea","lastPublishedDoi":"10.21203/rs.3.rs-7624319/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7624319/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003eThe 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.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eObjective: \u003c/strong\u003eTo characterize the TTC complex in normal and DWM fetuses and assess its visibility on routine prenatal MRI.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMaterials and methods: \u003c/strong\u003eNine 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).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eThe 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\u003cstrong\u003e. \u003c/strong\u003eOn fetal MRI, the tela was confidently visible in 28\u003cstrong\u003e–\u003c/strong\u003e33% of cases, with moderate agreement (κ\u003cstrong\u003e 0.49, 95% CI 0.34–0.62\u003c/strong\u003e). The choroid plexus was confidently visible in 21\u003cstrong\u003e–\u003c/strong\u003e27% of cases, with fair agreement (κ 0.27\u003cstrong\u003e, 95% CI \u003c/strong\u003e0.09\u003cstrong\u003e–\u003c/strong\u003e0.43).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion: \u003c/strong\u003eThe 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.\u003c/p\u003e","manuscriptTitle":"The Fetal Taenia–Tela Choroidea Complex: A Radiologic–Pathologic Correlation from Normal Anatomy to Dandy-Walker Malformation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-25 15:39:53","doi":"10.21203/rs.3.rs-7624319/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"97bf2f32-4cc0-4186-81e1-4d0c350b160f","owner":[],"postedDate":"September 25th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-12-16T18:09:01+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-25 15:39:53","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7624319","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7624319","identity":"rs-7624319","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}