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DOI: 10.1055/s-0041-1739764
The vermian-crest angle: towards the establishment of a prediction model for fetal posterior fossa anomalies
Background and purpose An accurate categorization of fetal upward rotation of the cerebellar vermis remains a challenge in prenatal medicine. Recently, a new parameter of the posterior fossa (PF), based on the internal occipital crest, the Vermian-Crest Angle (VCA), has been evaluated at three-dimensional ultrasound (3D-US) (1) and prenatal MRI (2). Our aim was to test the VCA in fetuses with a pathological PF at 3D-US and assess agreement with MRI.
Materials and Methods We measured by multiplanar 3D-US the VCA in fetuses with any PF anomaly and compared it to 3D-US published reference values for normal cases (1); we assessed agreement to MRI published values as well (2). Statistical analyses were performed using Student’s t-test and the one-way analysis of variance (ANOVA) with the Bonferroni adjustment [1] [2].
Results Seventy fetuses at 24.5±5.45 weeks with Blake’s pouch cyst (BPC) (n=18), Dandy–Walker Malformation (DWM) (n=11), Mega Cisterna Magna (MCM) (n=28) and Vermian Hypoplasia (VH) (n=13) were identified. The VCA changed significantly in the DWM (130.58°±16.75°; p≤0.01) and BPC (93.57°±20.09°; p≤0.05) sub-groups of anomalies, in comparison to 3D-US published reference values for normal cases; the angle increased progressively with the severity of the condition:a measurement of>88° was found in BPCs, while a VCA>109° was suggestive of a DWM. On the contrary, the VCA did not change in cases of VH (70.01±11.98; p=0.95) nor in cases of MCM (66.78 ± 12.82; p=0.84). Comparing subgroups with the respective published MRI data (2), we found a high agreement with 3D-US (p=0.76 MCM, p=0.88 VH, p=0.67 BPC, p=0.79 DWM).
Conclusions The VCA does provide valuable additional information for the assessment of vermian position within the PF at 3D-US. The high agreement with MRI measurments reinforces the synergy between 3D-US and MRI in the diagnostic work-up of PF anomalies. In combination with the other existing parameters, the VCA may be helpful for addressing the differential diagnosis and categorization of PF anomalies.


Publication History
Article published online:
26 November 2021
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References
- 1 Spinelli M. et al. The Vermian-Crest Angle: A New Method to Assess Fetal Vermis Position within the Posterior Fossa Using 3-Dimensional Multiplanar Sonography. Fetal Diagn Ther 2019; 46 (04) 223-230
- 2 Spinelli M. et al. The “vermian-crest angle”: does it allow accurate categorisation of fetal upward rotation of cerebellar vermis on intrauterine MRI. A pilot study. Clin Radiol 2019; 74 (06) 489.e1-489.e7