Abstract

Transvaginal high-resolution ultrasound and three-dimensional (3D) ultraosund have been establishing sonoembryology in the first trimester as well as neurosonography. Fetal brain is rapidly developing and changing its appearance week by week during pregnancy. The brain is the most important organ but it is quite hard to observe detailed structure of this organ by conventional transabdominal sonography. It is possible to observe the whole brain structure by magnetic resonance imaging in the post half of pregnancy, but it is difficult in the first half of gestation and transvaginal high-resolution 3D ultrasound is the most powerful modality. As for brain vascularization, main arteries and veins have been demonstrated and evaluated in various CNS conditions. Transvaginal high-resolution 3D ultrasound can demonstrate cerebral fine vascular anatomy such as medullary vessels and it is greatly expected to estimate neurological prognosis in relation with vascular development during fetal period.