Radiologia Brasileira - Publicação Científica Oficial do Colégio Brasileiro de Radiologia

The first three-dimensional ultrasound system (3D-US) in obstetrics was proposed by Baba et al.⁽¹⁾ in 1986 and consisted of a mechanical arm attached to a two-dimensional convex probe that was able to capture two-dimensional images, which were sent to a computer and processed into three-dimensional volumes. However, the long time required for processing and the low quality of the images impeded their clinical application.

In the early 1990s, the advent of automatic scanning volumetric probes opened new horizons in the three-dimensional evaluation of the fetus. In 1992, Kuo et al.⁽²⁾ demonstrated the first application of 3D-US fetal evaluation. Since then, various applications of 3D-US in fetal medicine have been described, such as the evaluation of fetal malformations⁽³⁾, volumetric assessment of fetal organs⁽⁴⁾, cardiac assessment⁽⁵⁾, evaluation of the central nervous system⁽⁶⁾, and the use of power Doppler⁽⁷⁾. More recently, new software, such as HDlive, allow a realistic vision of the face and surfaces of the fetus⁽⁸⁾. The main advantages of 3D-US would be the following: evaluation of a fetal structure simultaneously in the three orthogonal planes; fetal assessment in the absence of the mother; less reliance on operator skills; and the possibility of sending three-dimensional volumes for analysis at tertiary care centers⁽⁹⁾.

At 25 years after the introduction of 3D-US in the clinical practice of fetal medicine, despite the greater availability of devices that are faster and produce images with higher resolution, as well as the involvement of examiners who are more experienced in the technique, questions remain about the real advantage in relation to the two-dimensional ultrasound (2D-US) for the maternal-fetal dyad.

In this issue of Radiologia Brasileira, Werner et al.⁽¹⁰⁾ present the experience of their group in the construction of virtual and physical 3D models of 26 singleton fetuses and 5 twin fetuses with various malformations, obtained through 3D-US, magnetic resonance imaging (MRI), and computed tomography (CT). The authors state that additive manufacturing technology allows the conversion of a virtual 3D model to a physical model, with precise dimensions, in a process that is fast and easy. They conclude that the physical 3D models allow greater interaction between the parent(s) and the fetus, as well as representing a method of continuing medical education. Since 2010, this research group has conducted a number of studies proposing the use of virtual and physical 3D models—based on data obtained with 3D-US, MRI, and CT—in the evaluation of various fetal malformations^(11–14), intrauterine infections ^(15,16) and maternal-fetal interaction in blind couples⁽¹⁷⁾. In all of those studies, the 3D models have allowed a better understanding of fetal disease by the medical team and by the parents, as well as enabling greater maternal-fetal interaction. In addition, the virtual 3D models enabled the virtual navigation by the fetal trachea in cases of cervical teratoma, in order to assess the degree of compression in the prenatal period and enable better management in childbirth and postpartum⁽¹⁸⁾. Although the printing costs of the physical 3D models make their use currently accessible only to a small portion of the population, we believe that more rapid technological development and broader dissemination of the method will soon make this diagnostic tool available to a larger portion of the population.

In summary, after 25 years of clinical practice of 3D-US in fetal medicine, various advances were made in prenatal diagnosis. However, certain questions remain unanswered. The answers to those questions could arise along with ongoing technological development. The virtual and physical 3D models allow a new form of fetal assessment by medical staff, in addition to increasing maternal-fetal interaction, especially in cases of blind couples.


REFERENCES

1. Baba K, Satoh K, Sakamoto S, et al. Development of an ultrasonic system for three-dimensional reconstruction of the fetus. J Perinat Med. 1989;17:19–24.

2. Kuo HC, Chang FM, Wu CH, et al. The primary application of three-dimensional ultrasonography in obstetrics. Am J Obstet Gynecol. 1992;166:880–6.

3. Merz E, Bahlmann F, Weber G. Volume scanning in the evaluation of fetal malformations: a new dimension in prenatal diagnosis. Ultrasound Obstet Gynecol. 1995;5:222–7.

4. Araujo Júnior E, Guimarães Filho HA, Pires CR, et al. Validation of fetal cerebellar volume by three-dimensional ultrasonography in Brazilian population. Arch Gynecol Obstet. 2007;275:5–11.

5. Rocha LA, Rolo LC, Barros FS, et al. Assessment of quality of fetal heart views by 3D/4D ultrasonography using spatio-temporal image correlation in the second and third trimesters of pregnancy. Echocardiography. 2015;32:1015–21.

6. Caetano AC, Zamarian AC, Araujo Júnior E, et al. Assessment of intracranial structure volumes in fetuses with growth restriction by 3-dimensional sonography using the extended imaging virtual organ computer-aided analysis method. J Ultrasound Med. 2015;34:1397–405.

7. Bortoletti Filho J, Nardozza LM, Araujo Júnior E, et al. Embryo vascularization by three-dimensional power Doppler ultrasonography at 7-10 weeks of pregnancy. J Perinat Med. 2009;37:380–5.

8. Araujo Júnior E, Santana EF, Nardozza LM, et al. Assessment of embryo/fetus during pregnancy by three-dimensional ultrasonography using the HD live software: iconographic essay. Radiol Bras, 2015;48:52–5.

9. Gonçalves LF, Lee W, Espinoza J, et al. Three- and 4-dimensional ultrasound in obstetric practice: does it help? J Ultrasound Med. 2005;24:1599–624.

10. Werner H, Santos JL, Belmonte S, et al. Aplicabilidade da técnica tridimensional na medicina fetal. Radiol Bras. 2016;49:281–7.

11. Werner H, Rolo LC, Araujo Júnior E, et al. Manufacturing models of fetal malformations built from 3-dimensional ultrasound, magnetic resonance imaging, and computed tomography scan data. Ultrasound Q. 2014;30:69–75.

12. Werner H, Lopes J, Tonni G, et al. Physical model from 3D ultrasound and magnetic resonance imaging scan data reconstruction of lumbosacral myelomeningocele in a fetus with Chiari II malformation. Childs Nerv Syst. 2015;31:511–3.

13. Werner H, Lopez J, Tonni G, et al. Plastic reconstruction of fetal anatomy using three-dimensional ultrasound and magnetic resonance imaging scan data in a giant cervical teratoma. Case report. Med Ultrason. 2015;17:252–5.

14. Menezes GA, Araujo Júnior E, Lopes J, et al. Prenatal diagnosis and physical model reconstruction of agnathia-otocephaly with limb deformities (absent ulna, fibula and digits) following maternal exposure to oxymetazoline in the first trimester. J Obstet Gynaecol Res. 2016;42:1016–20.

15. Werner H, Fazecas T, Guedes B, et al. Intrauterine Zika virus infection and microcephaly: correlation of perinatal imaging and three-dimensional virtual physical models. Ultrasound Obstet Gynecol. 2016;47:657–60.

16. Werner H, Sodré D, Hygino C, et al. First-trimester intrauterine Zika virus infection and brain pathology: prenatal and postnatal neuroimaging findings. Prenat Diagn. 2016; 36:785-9.

17. Werner H, Lopes J, Tonni G, et al. Maternal-fetal attachment in blind women using physical model from three-dimensional ultrasound and magnetic resonance scan data: six serious cases. J Matern Fetal Neonatal Med. 2016;29:2229–32.

18. Werner H, Lopes dos Santos JR, Fontes R, et al. Virtual bronchoscopy for evaluating cervical tumors of the fetus. Ultrasound Obstet Gynecol. 2013;41:90–4.










Tenured Adjunct Professor of Fetal Medicine in the Department of Obstetrics of the Escola Paulista de Medicina da Universidade Federal de São Paulo (EPM-Unifesp), São Paulo, SP, Brazil. E-mail: araujojred@terra.com.br