Introduction Sonography is the technique of choice for routine evaluation of the brain in premature infants and for the study of a broad range of pathological condi- tions in full-term neonates. Improvements in image resolution and the use of additional acoustic win- dows, such as the posterior and mastoid fontanelles, now allow proper visualization of the brain stem and posterior fossa. Familiarity with the sono- graphic brain anatomy and artifacts related to the technique is essential for proper interpretation of the studies. This pictorial essay illustrates several normal struc- tures, anatomic variants and scanning artifacts related to the ventricular system, choroid plexus and brain parenchyma, which can mimic pathology on neonatal cranial sonography. The work is based on cranial US studies that were performed on a routine basis on 176 premature neonates and on 26 full-term newborns to investigate brain pathology. We used the anterior, posterior and mastoid fontanelles as acoustic windows. All the images referred to as pitfalls belonged to infants who were followed up using US and found to be neurologically and developmentally normal on clini- cal assessment. Images of several brain disorders are included for comparison purposes. ORIGINAL ARTICLE Pediatr Radiol (2003) 33: 110–117 DOI 10.1007/s00247-002-0836-y Goya Enrı´quez Flavia Correa Javier Lucaya Joaquim Piqueras Celestino Aso Aranzazu Ortega Potential pitfalls in cranial sonography Received: 8 February 2002 Accepted: 29 August 2002 Published online: 22 November 2002 Ó Springer-Verlag 2002 G. Enrı´quez (&) Æ F. Correa Æ J. Lucaya J. Piqueras Æ C. Aso Department of Pediatric Radiology, Hospital Vall d’Hebron, Ps. Vall d’Hebron 119-129, 08035 Barcelona, Spain E-mail: enriquez@cs.vhebron.es Tel.: +34-93-2746793 Fax: +34-93-2746775 A. Ortega Department of Pathology, Hospital Vall d’Hebron, Ps. Vall d’Hebron 119-129, 08035 Barcelona, Spain Abstract Background: We present several anatomic variants of the brain and artifacts related to scan- ning techniques which could be misinterpreted as lesions on neonatal cranial sonography. Materials and methods: The findings were derived from US studies performed on 176 premature infants and 26 full-term newborns, using the anterior, posterior and mastoid fontanelles as acoustic windows. Results: The pseudolesions are divided into three groups: ventricular system (asymmetric lateral ventricle size and coarctation of the lateral ventricles); choroid plexus (‘‘split’’ choroid, ‘‘truncated’’ choroid and choroid cyst); and brain paren- chyma (peritrigonal blush, thalamic pseudolesion, pseudo-absence of the inferior vermis, occipital pseudomass and calcar avis simu- lating intraventricular clot). We provide images of these pseudole- sions and clues to their differentia- tion from true brain pathology. Images of several brain disorders are included for comparison. Knowledge of these potential pitfalls is essential for proper inter- pretation of US brain studies and will help to avoid the use of other more invasive diagnostic tests. Conclusions: Misleading images seen on US examination of the neonatal brain that could be misinterpreted as pathology are presented, with clues to their differentiation from true lesions. Keywords Ultrasound Æ Brain Æ Variants Æ Pitfalls