Fetal MRI: normal gestational landmarks for cerebral biometry, gyration and myelination

Purpose: Up until the last 10 years, normal cerebral gestational landmarks were assessed by ultrasonographic and fetopathologic studies. The purpose of this paper is to display the possibilities provided by fetal MRI in the evaluation of fetal cerebral biometry, normal sulcation and myelination. Methods: Two hundred and twenty-five fetuses (with a normal brain) were studied prospectively using a standardised method. The gestational age ranged from 22 to 38 weeks. The main data concerning biometry of various cerebral structures at those terms are given. Discussion: In contrast to ultrasound, MRI allows measurements of brain (and not skull), which are available independently of the position of the fetal head. The timing of the appearance of the different sulci is also available using MRI. It is considered to be a good marker of fetal brain maturation. The biochemical modifications contemporary to myelination make it possible to evaluate this phenomenon in the fetal brain using MRI.