A new view of the neonatal brain: clinical utility of supplemental neurologic US imaging windows.

Anterior fontanelle imaging has traditionally been the mainstay of neonatal cranial ultrasonography (US). However, this traditional approach has limited diagnostic accuracy, which has led to increasing use of two alternate neurologic US imaging techniques: posterior fontanelle imaging and mastoid fontanelle imaging. These alternate techniques can help detect pathologic conditions and structural malformations in the neonatal brain. Posterior fontanelle imaging allows improved detection of intraventricular hemorrhage. This technique better demonstrates subtle differences in echogenicity between clot and a choroid glomus and depicts clot extending into the occipital and temporal horns. Mastoid fontanelle imaging is particularly useful in detecting hemorrhage involving the brainstem, cerebellum, and subarachnoid cisterns. It greatly facilitates clot detection in the fourth ventricle and cisterna magna because the tissues surrounding these structures are normally echogenic. Mastoid fontanelle imaging can also help distinguish holoprosencephaly from aqueductal stenosis and identify small malformations of the posterior fossa. Color Doppler US may help identify normal variants such as calcar avis and lobular choroid plexus, and adjunct magnetic resonance imaging can help distinguish normal structures from a true Dandy-Walker variant. Use of posterior fontanelle imaging and mastoid fontanelle imaging can significantly augment the diagnostic power of neurologic US.