Assessment of cortical gyrus and sulcus formation using MR images in normal fetuses

The purpose of this study was to estimate the development of the gyrus and sulcus formation in normal fetuses on the basis of the neuroanatomical findings using MR images in relation to gestational age.

The MR images were obtained from 109 normal fetuses from 18 to 39 weeks of gestation with no neurological problems. The MR images were classified into 8 stages of development for the gyrus and sulcus formation in the frontal and temporal lobes on the basis of the neuroanatomical findings reported by Chi et al. (1977) and Dorovini-Zis and Dolman (1977). We examined retrospectively the relationship between our classification and gestational age in comparison with the five-stage classification proposed by McArdle et al. (1987).

There were significant differences in the gestational age among the 8 groups (P < 0.001). Multiple comparison of individual groups revealed significant differences in the gestational age among the groups (P < 0.05). Images from 28 to 34 weeks of gestation were classified into 4 stages in our classification, while being covered by one stage in McArdle's classification.

Our classification is useful for the assessment of fetal cerebral maturation during the third trimester of pregnancy and may contribute to the prenatal diagnosis of developmental delay of the gyrus and sulcus formation.