Survival rates for preterm infants have risen dramatically owing to the latest prenatal and postnatal treatments and modern, well-equipped and well-staffed neonatal intensive care units (1). Cranial sonography (US) is the primary imaging technique for evaluation of the brain in these patients (2-4).

Although anterior fontanel imaging is the main imaging approach of the neonatal cranial US, this traditional approach has some limitations in demonstrating posterior fossa pathologies (5). The mastoid fontanel is the thinnest region of the temporal bone at the junction of the squamosal, lambdoid, and occipital sutures and does not fuse until 2 years of age (6). Visualization of posterior fossa anatomy and pathologies of the neonatal brain is best achieved by obtaining images through the mastoid fontanel (Fig. 1). This magic window also gives some information about some supratentorial pathologies.