The fetal brain is a structure which evolves continuously throughout gestation. Visualization of the relevant anatomic details of the corpus callosum and cerebellar vermis in particular, was noted by both 2D and 3D imaging and then these images were compared qualitatively. Median planes were also obtained by 3D technique.
The supero-inferior dimension of vermis was documented. In the posterior fossa, the vermis was also seen in both axial and midsagittal plane. The length and the thickness of the corpus callosum were measured. On 2D imaging, direct visualization of corpus callosum was performed both on sagittal and coronal views. Ten fetuses had anomalies involving the midline cerebral structures. Of the 60 cases included in the present study, 50 fetuses showed normal intracranial anatomy. Both transabdominal and transvaginal routes were used to assess the midline structures depending upon the position of the fetal head. 2D median planes were obtained by aligning the transducer through the anterior and posterior fontanelle and the sutures. Ultrasound examination was performed by using Voluson E8 ultrasound system (GE healthcare) with 4–8 MHz transabdominal probe and 8–12 MHz transvaginal probe. This was a prospective study of 60 consecutive pregnancies at 19–28 weeks of gestation. To improve upon the detection rate, a combination of sagittal, coronal, parasagittal, and angled views on 2D imaging to visualize the midline structures was used. The study was performed to evaluate the effectiveness of a simplified approach by using 2D technique for evaluation of the midline structures of the fetal brain and also comparing it with the 3D technique. With this background knowledge of anatomy on 3D, these planes can be obtained on two dimensional (2D) ultrasound with better resolution. In fact, the evolution of three dimensional (3D) ultrasound has given a new dimension of looking at fetal brain. The first plane passes through the cavum septum pellucidum and the atria of the lateral ventricles (transventricular plane), the second through the cavum septum pellucidum and the thalami (transthalamic plane), and the third passes through the posterior fossa and the cerebellum (transcerebellar plane). The imaging of fetal brain begins by evaluating the three standard planes.
The development of fetal brain is a complex mechanism producing remarkable changes in its sonographic appearance throughout pregnancy. With high resolution probes, 2D median planes are good enough which can substitute 3D median plane views, especially in developing countries where there is less availability of 3D equipment and expertise of the 3D technique. The 2D median views yielded excellent display of anatomy as well as the abnormalities. In all cases, the diagnosis could be made by both 2D and 3D views but 3D added clinically useful information especially in two fetuses with posterior fossa lesions. There was a good correlation between 2D and 3D images. TVS was also used in fetuses with breech presentation. 2D median planes were obtained in all, usually more easily and rapidly. 3D midline sagittal planes could be visualized in 48/50 normal fetuses. Visualization of the relevant anatomic details, corpus callosum and cerebellar vermis in particular, was noted by both 2D and 3D images. 2D and 3D median planes were compared qualitatively. 2D median planes were obtained by aligning the transducer through the anterior and posterior fontanelle and the sutures by either transabdominal sonogram or transvaginal sonogram (TVS) approach. Ultrasound examinations were performed on Voluson E8 BT10. The study was performed in 60 fetuses with normal intracranial anatomy and 10 fetuses with anomalies involving the midline cerebral structures from 19 to 28 weeks of gestation. The objective of the present study was to investigate the effectiveness of a simplified approach by using two dimensional (2D) technique for evaluation of the midline structures of the fetal brain and comparing it with the three dimensional (3D) technique.