WHERE IS MY BABY? A FAST FETAL HEAD AUTO-ALIGNMENT IN 3D-ULTRASOUND

Ultrasonography is the main modality for prenatal screen-ing examination of the fetal central nervous system. Due to the variability of the position of the fetal brain relatively to the probe, identification of structures of interest requires both time and a high level of expertise. The method presented in this paper aims at helping the clinician navigate through the brain by automatically aligning the head in near real time (<1 s) in a 3D ultrasound volume. The alignment is obtained by defining a frame of reference (i.e. an orthogonal basis and a center point) based on the skull, the mid-sagittal plan and the orbits of the eyes; their signals remain strong and stable across acquisitions. They are detected by combining state-of-the-art techniques (random forests and template deforma-tion). Our method has proven fast and accurate on a dataset of 78 volumes (19-24 gestational weeks): maximal alignment errors ’ medians range from 5.1 to 5.8mm for the transcerebel-lar, transventricular and transthalamic planes. Index Terms — ultrasound, auto-alignment, random for-est, template deformatio