Evaluation of vermian lobulation is essential in assessment of the vermian maturity. MRI is a useful tool in assessment of the fetal posterior fossa.
Normal Vermian lobulation by weeks 1:
- By 21 weeks - Prepyramidal fissure can be seen between the tuber and pyramis.
- 21 to 22 weeks - Preculminate fissure can be seen in between the central lobule and culmen.
- 24 weeks - Secondary fissure can be seen between the pyramis and uvula
- From 27 weeks - all vermian lobules and fissures become visible