Three-dimensional ultrasound in obstetrics practice: myth or reality? - Revista Brasileira de Ginecologia e Obstetrícia

Three-dimensional ultrasound in obstetrics practice: myth or reality? |

Since the introduction of sonography into clinical practice, two-dimensional ultrasound (2DUS) has represented the standard application in obstetrics care. Nonetheless, technological advancement has brought to healthcare givers a new opportunity that is three-dimensional ultrasound (3DUS). Are there nowadays convincing evidence that 3DUS offer advantages over 2DUS and have gained recognized as well as well established role to justify its inclusion into routine obstetrics practice? The technological advancement reached by 3DUS warrant appropriate operator training program in order to acquire expertise to manage ultrasound applications and software. When this "goal" is reached, there is no doubt concerning the fact that one of the main advantages of 3DUS over 2DUS is represented by anatomic acquisition of a volume. Once a volume data set has been acquired, it can be sectioned on-line or transferred to an external personal computer for post-processing analysis. At this stage, "navigation" within the volume is possible, and operators can then freely sectioned or rendered the volume on-demand. This is of dramatic importance in teaching and training clinical setting. Furthermore, volume can be acquired on standardized plane at remote site even by inexperienced operator in 3DUS and send for expert consultation using telemedicine. Although stored volume data sets are large, up to 10 megabyte, they can be compressed to about 15 to 20% of the original file size and submitted via Digital Imaging and Communications in Medicine (DICOM) technology for off-line consultation without noticeable loss of details or image quality. Moreover, volume data sets can be shared by expert on dedicated website and be used in multicenter studies while demonstrating a high sensitivity and reliability ^, .

3DUS with its applications allow operators a simultaneous and less time consuming (when compared with 2DUS) rendering of the anatomical landmarks in three orthogonal planes when using the multiplanar mode. In such case, the region of interest is displayed on the upper left quadrant on the ultrasound video equipment while the sagittal plane, the coronal and the axial are rendered in plane A, plane B and plane C, respectively. The planes obtained from the 3D volume are parallel and not oblique or at an angle, as is the case with conventional 2DUS. In addition, when comparing 2DUS vs. 3DUS studies of pathological cases, one of the most important advantages offered by "navigating" inside the volumes generated by 3DUS is the ability to follow the green "reference" dot that indicates the same anatomical point on all three orthogonal planes and thus facilitating identification of the targeted site. With technological advancement of "real-time" high-resolution 3DUS machine, volume data sets of the "volume of interest" (VOI) can be acquired in only few seconds and motion artifacts due to fetal movements may be minimized. In case of active fetal movements, volume can be acquired using the 3D live mode (4D) facility rather than using the static 3D mode. This option has demonstrated its clinical value when reconstructing the fetal face and/or the cardiac structures using the spatio-temporal-image correlation (STIC) technique ^- . Tonni et al.⁵ have demonstrated that 3DUS have enhanced the diagnostic accuracy in detecting cleft lip (CL) and cleft palate (CP) in a routine second trimester scan on low-risk pregnant women. To enhance prenatal detection of CL/CP, different 3DUS techniques as the "reverse face", the "flipped" face, the "oblique" and the "angle insonation" view have been developed and proposed for inclusion into clinical obstetrics practice.

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