Three-dimensional Ultrasonographic Evaluation of the Fetal Posterior Fossa

Posterior fossa malformations can be considered as very frequent brain anomalies.Irrespective of the rapid development of fetal imaging, the frequency of both false-negative and false-positive diagnoses of posterior fossa anomalies did not change, making the diagnosis difficult.Fetal posterior fossa abnormalities may be broadly divided into hindbrain malformations, including diseases with cerebellar or vermian agenesis, aplasia or hypoplasia, and cystic posterior fossa anomalies, and cranial vault malformations or Chiari malformations.Categorization of posterior fossa anomalies is still controversial and there is no uniform approach.Multidimensional mode in fetal neurosonography by 3D probes has several advantages over standard 2D probes.Unlimited offline analysis by using three orthogonal planes of the fetal brain, tomographic ultrasound imaging (TUI), and volume contrast imaging (VCI) may be obtained by a single 3D acquired data.These neuroimaging modes allow obtaining more precise information on fetal posterior fossa and the results are comparable to those obtained with fetal magnetic resonance imaging (MRI).Three-dimensional ultrasonography is an invaluable instrument for differential diagnosis of posterior fossa anomalies.Transabdominal or transvaginal 3D ultrasonography allows thorough assessment of the complex anatomic structures of the posterior fossa and improves diagnostic accuracy and diagnostic confidence having a positive clinical effect in most of the cases.