Analysis of the Anatomical Variability of Fetal Brains with Corpus Callosum Agenesis

Corpus Callosum Agenesis (CCA), one of the most common congenital anomalies, has uncertain neurodevelopmental outcome, especially when the disease is isolated. To provide parents with informed counselling, it is crucial to identify anatomical markers linked to a predicted outcome early in pregnancy. Quantitative exploration of fetal brains with CCA is rare and has been mostly limited to the study of specific brain structures. Here, we propose a pipeline to analyse fetal brain Magnetic Resonance Imaging (MRI) that is based on diffeomorphic transformation. It consists in two steps: a semi-automatic fetal MRI preprocessing procedure and a pipeline to quantify anatomical deviations from normal development. Following MRI preprocessing, each volumetric fetal brain is compared to an age-matched healthy template brain at a global scale using registration. Deformations are parallel transported to the same space to correct age differences between fetuses. Deformation modes specific to CCA are identified using Principal Component Analysis and classification. The pipeline is tested on retrospectively selected MRIs from 38 healthy fetuses and 73 fetuses with CCA. In accordance with more local analyses, the most relevant deformation mode for classification combines well-known alterations of brains with CCA. This preliminary work is promising for the quantitative exploration of abnormal fetal brains and will be used in the future to identify anatomical features correlated to poor clinical outcome