Evaluation of Brain Volume and Dimensions in Healthy Fetuses Using Obstetrics Ultrasound Examination at 14-34 Weeks of Pregnancy.

Study design:

This is a prospective study that evaluates normal fetal brain cortex development from 14 to 34 WG using 2D and 3D ultrasound in singleton low risk pregnancies with unknown obstetrical complications. The clinical and obstetrical data will be obtained prior to the US evaluation; and will include maternal medical and obstetrical data and confirmation of fetal gestational age based on first day of the last menstrual cycle (LMP) supported by well documented CRL from first trimester US. Brain biometric and sulcation analysis includes:

1. Routine measurement of BPD, HC, OFD, cisterna magna, cerebellum, lateral ventricle(1).
2. Parietoccipital fissures will be measured in an axial slice above the transthalamic plane used for the BPD assessment tracing a perpendicular line from the longitudinal fissure to the apex of the parietoccipital fissures (4).
3. Insular depths will be measured in the axial slice located immediately below the anterior commissure and the cavum septum pellucidum, tracing a perpendicular line from the median longitudinal fissure to the most external border of the insular cortex(4).
4. Lateral fissure depths will be measured in the same plane described above, with a continuing line starting from the most external border of the insular cortex to the interface conformed between the subarachnoid space and the skull(4).
5. Cingulate fissures will be measured in the mid-coronal plane tracing a perpendicular line from the median longitudinal fissure to the apex of the cingulate fissures.
6. Calcarine fissures will be measured in the coronal transcerebellar plane as described in ISOUG, tracing a perpendicular line from the median longitudinal fissure to the apex of the calcarine fissures.

Two measurements will be taken by two examiners in order to evaluate intraobserver and interobserver reproducibility.

In all the cases a maximum effort will be undertake to obtain adequate volumes of the brain in order to enable offline evaluation of the different structures.