Fetal MRI of Normal Brain Development

Abstract

The fetal brain is substantially different from the neonatal brain in terms of its structure and connectivity. Fetal MRI, beginning at 16–18 GW (gestational weeks), can be used to study fetal brain development and maturation in vivo. T2-weighted (T2W), T1-weighted (T1W), and diffusion-weighted (DW) imaging sequences can be used primarily to demonstrate morphology, parenchymal lamination, sulcation and gyration, the width of the subarachnoid spaces, and the size and shape of the midline structures. It is essential to understand MR signal changes associated with maturation, including the appearance and disappearance of transient structures, the underlying histological ­development of the fetal brain as well as the timing of development of landmarks in maturation in order to interpret normal and abnormal findings. It is the basis for understanding how neurogenetic development can be disrupted during vulnerable periods by different pathological processes, and how genetically controlled events in development correlate with functional development. The maturational stages of the fetal cerebral cortex, white matter, temporal lobe, and cerebellum, including structures that appear transiently in the developing brain as shown by various MR sequences, will be reviewed in this chapter.