Sequential analysis of the normal fetal fissures with three-dimensional ultrasound: a longitudinal study.

OBJECTIVE: to perform a sequential analysis of the main cortical fissures in normal fetuses using 3D ultrasound. METHODS: a cohort of patients with uncomplicated singleton pregnancies underwent three consecutive transabdominal scans at 19-21, 26-28 and 30-34 weeks. Volumes of the fetal head were acquired and searched in the multiplanar mode for the following cortical fissures: sylvian, parieto-occipital, calcarine, hippocampus and cingulate. A qualitative analysis of these sulci was performed in each volume by an experienced operator (A) and a trainee (B). By placing the dot on the sulcus in one plane, it was evaluated whether it was visible also in the other planes. RESULTS: 50 patients were included in the study. At 19-21 weeks, the sylvian and parieto-occipital sulci were visualized on at least one plane by both operators in all cases. At 26-28 weeks, all fissures were visualized by both operators on at least one plane, with no significant difference between the performances of the two operators. At 30-34 weeks, a mild overall decline in the accuracy of identification of all the cerebral fissures was observed. CONCLUSIONS: 3D multiplanar mode allows a systematic evaluation of the cortical fissures in normal fetuses since midtrimester