OC028: The role of Tomographic Ultrasound Imaging (TUI) in transfrontal volume analysis of midline fetal cerebral structures

Abstract

Methods: This was a prospective study in 201 consecutive singleton pregnancies at 20–32 weeks of gestation (134 cases between 20–25 weeks and 67 between 26–32 weeks). In each case, we attempted within a period of 15 minutes to obtain a transabdominal transfrontal view (TF) by aligning the ultrasound beam with the patent metopic suture. The exact mid sagital plane was defined by the visualization of the entire corpus callosum, the cavum septi pellucidi, the third ventricle, the brain stem, the fourth ventricle (4v) and the cerebellar vermis (CV). Gentle manipulation of the fetal head was constantly used to allow access to the metopic suture. Results: The TF view was successfully obtained in 190/201 consecutively examined normal fetuses (94.5%). In 11 cases the fetal position was such that it was not possible, within the allocated 15 minutes, to image the fetal profile. All these 11 fetuses were in cephalic presentation. The structures included in the mid sagital plane was completely visualize in 183/190 cases (96%, P < 0.0001). In 7 cases, the 4v or the CV was incompletely analyzed due to poor resolution related to maternal habitus. All of these 7 fetuses were in cephalic presentation. Conclusions: The TF was feasible. If the standard examination includes a view of the facial fetal profile, a rapid alignment of the ultrasound beam with the metopic suture, sometimes requiring manipulation of the fetal head, provide direct visualization for assessment of midline cerebral structures in the vast majority of the fetuses included in our study. The TF view could represent a step towards incorporating a comprehensive neuron scan into routine targeted organ evaluation.