Radiological evaluation of the posterior fossa is an essential part of the routine fetal assessment, including vermian maturity assessment.
Ultrasonography is a readily available diagnostic tool in the assessment of the fetal posterior fossa but is sometimes limited due to a variety of pathologies that can look similar and even identical on standard axial ultrasonography. Also, true sagittal and coronal views of the posterior fossa are difficult to achieve, leading to false positive vermian pathologies 1. The use of fetal MRI is extremely useful in difficult cases.
The role of MRI includes 2:
- documentation of the normal MRI landmarks of developing fetal posterior fossa
- prediction of poor neurological prognosis by assessment of the degree of lobulation
- diagnostic strategy in difficult cases, e.g. Dandy-Walker continuum, vermian hypoplasia, mega cisterna magna, posterior fossa arachnoid cyst
MRI assessment of vermian maturity includes 3:
- 1. Carroll SG, Porter H, Abdel-Fattah S, Kyle PM, Soothill PW. Correlation of prenatal ultrasound diagnosis and pathologic findings in fetal brain abnormalities. Ultrasound in obstetrics &gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 16 (2): 149-53. doi:10.1046/j.1469-0705.2000.00199.x - Pubmed
- 2. Adamsbaum C, Moutard ML, André C, Merzoug V, Ferey S, Quéré MP, Lewin F, Fallet-Bianco C. MRI of the fetal posterior fossa. Pediatric radiology. 35 (2): 124-40. doi:10.1007/s00247-004-1316-3 - Pubmed
- 3. Robinson AJ, Blaser S, Toi A, Chitayat D, Halliday W, Pantazi S, Gundogan M, Laughlin S, Ryan G. The fetal cerebellar vermis: assessment for abnormal development by ultrasonography and magnetic resonance imaging. Ultrasound quarterly. 23 (3): 211-23. doi:10.1097/RUQ.0b013e31814b162c - Pubmed