Volume 45, Issue 6 - Special issue 3D / 4D sonography

Three-/four-dimensional (3D/4D) imaging enables a more detailed survey of the embryo and the fetus compared to two-dimensional (2D) ultrasound. The availability of several display modes and standardized examinations permits the demonstration of both the normal and abnormal fetal anatomy in controlled planes and rendered images from different angles. This allows the demonstration of even subtle fetal defects in an ideal sectional plane in a precisely rendered surface or transparent image viewed from an optimal angle. When counseling the parents, the rendered images can help them understand the severity of an existing malformation or, conversely, ensure them of the absence of any fetal abnormality. This is particularly useful in cases with an increased recurrence risk of a specific fetal malformation.

With all of our present knowledge, high technology diagnostic equipment, electronic databases and other available supporting resources, detection of fetal syndromes is still a challenge for healthcare providers in prenatal as well as in the postnatal period. Prenatal diagnosis of fetal syndromes is not straightforward, and it is a difficult puzzle that needs to be assembled and solved. Detection of one anomaly should always raise a suspicion of the existence of more anomalies, and can be a trigger to investigate further and raise awareness of possible syndromes. Highly specialized software systems for three- and four-dimensional ultrasound (3D/4D US) enabled detailed depiction of fetal anatomy and assessment of the dynamics of fetal structural and functional development in real time. With recent advances in 3D/4D US technology, antenatal diagnosis of fetal anomalies and syndromes shifted from the 2 nd to the 1 st trimester of pregnancy. It is questionable what can and should be done after the prenatal diagnosis of fetal syndrome. The 3D and 4D US techniques improved detection accuracy of fetal abnormalities and syndromes from early pregnancy onwards. It is not easy to make prenatal diagnosis of fetal syndromes, so tools which help like online integrated databases are needed to increase diagnostic precision. The aim of this paper is to present the possibilities of different US techniques in the detection of some fetal syndromes prenatally.

Conjoined twins are a rare, but serious, complication of monozygotic twins. Early prenatal diagnosis of conjoined twins is increasingly made with transvaginal ultrasound and color Doppler studies. Most prenatally diagnosed conjoined twins are terminated due to the high perinatal mortality, but advancement in pediatric surgery has allowed for successful postnatal separation in a small number of cases, and some parents may consider this option over termination of pregnancy. It is important to get a detailed prenatal ultrasound for the site and extent of fusion for an accurate categorization. Three-dimensional ultrasound (3DUS) provides images that can facilitate counselling for the parents. Additional information that impacts on diagnosis, prognostication, and perinatal management of conjoined twins could be obtained from selective use of 3DUS, particularly those with atypical fetal union. Most of the proposed additional benefits of 3DUS are based on case reports. Magnetic resonance imaging (MRI) has been increasingly used for the purpose of identifying intricate organ sharing. Because of the rarity of this condition, and the heterogeneity of fetal fusion, added benefits of either 3DUS or MRI for prenatal diagnosis and perinatal management of conjoined twins have not been demonstrated by well-conducted clinical trials. This article aims to review clinical application of various 3DUS display modes in prenatal assessment of conjoined twins, focusing on their potential additional benefits, risks and misuses. 3DUS may help detecting additional findings that are not possible with 2DUS, but, it has not been scientifically shown to improve the survival rate of the twins or reduce maternal morbidity.

Abstract: The aim of this review is to discuss three dimensional (3D) power Doppler of the placenta and its clinical applications. There is a strong clinical need to develop noninvasive, simple and widely available methods of evaluating in vivo placental function to assess fetal wellbeing. While conventional ultrasound is a proven tool in the evaluation of fetal structural anomalies and health, its ability to assess placental function, especially prior to the onset of fetal compromise, is the subject of ongoing investigation. Three dimensional power Doppler has the ability to detect vascularity and blood flow with greater detail than conventional ultrasound, which has led to its investigation in preeclampsia, fetal growth restriction, and other placental vascular abnormalities. While more data are needed on the optimal imaging protocol and its predictive ability for clinical outcomes, 3D power Doppler is emerging as a promising new technology that will improve the evaluation of placental function.

The anomalies in placental insertion and invasion, such as placenta previa and the various forms of abnormally invasive placenta, are today a rising obstetric pathology. Two-dimensional (2D) ultrasonography is the gold standard in the diagnosis of abnormally invasive placenta (AIP), but the important feto-maternal impact of this pathology suggests the opportunity to employ all the available diagnostic techniques, such as three-dimensional (3D) power Doppler. This technique allows acquiring multiplanar images on coronal, axial and sagittal planes and with a rotational technique, it permits visualizing the placenta-bladder interface more accurately. Consequently, it allows a better study of the degree of bladder invasion, which is information that has a great impact on the subsequent counseling and management. Thus, 3D power Doppler represents an important technique complementary to 2D ultrasound in the diagnosis of AIP. The aim of this paper is to illustrate the possible applications of this procedure, referring to the main literature data.

Objective: To assess whether there is a difference in the behavior of fetuses of pregnant women with diabetes under treatment with insulin, compared to fetuses of pregnant women without diabetes. Materials and methods: Kurjak’s antenatal neurodevelopmental test (KANET) – a method that, by application of four-dimensional (4D) ultrasound, assesses fetal behavior in a similar way that neonatologists perform a neurological assessment in newborns – was applied from 28 to 38 weeks of gestation to 40 pregnancies with pre-existing diabetes mellitus or gestational diabetes mellitus (GDM) requiring insulin (diabetic group) and to 40 non-diabetic cases, with otherwise low-risk pregnancies (non-diabetic group). Results: There were no statistically significant differences regarding maternal age (30.5±5.1 years for diabetic group vs. 29.8±6.2 years for non-diabetic group) and gestational age (32±1.6 weeks for the diabetic group compared to 33±1.2 weeks for the non-diabetic group). After analysis of the results obtained from application of KANET to each group, results of KANET had higher scores in the non-diabetic group. Conclusion: It appears that there are differences in the fetal behavior between diabetic and non-diabetic fetuses, and also the specific parameters – movements that were different between the two groups were identified.

Assessment of fetal neurobehavior and detection of neurological impairment prenatally has been a great challenge in perinatal medicine. The evolution of four-dimensional (4D) ultrasound not only enabled a better visualization of fetal anatomy but also allowed the study of fetal behavior in real time. Kurjak Antenatal Neurodevelopmental Test (KANET) was developed for the assessment of fetal neurobehavior and the detection of neurological disorders, based on the assessment of the fetus by application of 4D ultrasound in the same way that a neonate is assessed postnatally. KANET is a method that has been applied for the past 10 years and studies show that it is a strong diagnostic tool and can be introduced into everyday clinical practice. We present all data from studies performed up to now on KANET.

Fetuses show various facial expressions, such as blinking, yawning, sucking, mouthing, tongue expulsion, scowling, and smiling, assessed by four-dimensional ultrasound from the early second trimester of pregnancy. Moreover, some fetuses demonstrate emotion-like behaviors as noted in infants, children, and adults. Selective fetal responses to stimuli indicate a high degree of brain development, which is reflected in the facial reactions. The fetal face with its movements and expressions can mirror the fetal brain function and development during different stages of the fetus in utero . The fetal face might represent the key to opening the box containing the secrets of fetal brain function and development. Four-dimensional ultrasound may be an important modality in current and future research on fetal facial expressions and assist in the evaluation of the fetal brain function.

Aim: To assess the frequency of fetal movement and reproducibility of fetal movement counting in normal singleton pregnancies early in the second trimester using four-dimensional (4D) ultrasound. Methods: Twenty-nine singleton pregnancies were studied for 15 min employing 4D ultrasound at 14–16 (19 cases) and 17–19 (10 cases) weeks of gestation. The frequencies of eight fetal movements (head anteflexion, head retroflexion, body rotation, hand to face movement, general movement, isolated arm movement, isolated leg movement and mouthing movement) were evaluated. Results: The most frequent fetal movements were isolated arm movements at 14–16 and 17–19 weeks’ gestation. There was a significant difference only in the frequency of mouthing movement between 14–16 and 17–19 weeks’ gestation (P < 0.05). All fetal movements showed intra- and inter-class correlation coefficients greater than 0.87, with good intra- and inter-observer agreements. Conclusion: The difference in the frequency of mouthing movement at 14–16 and 17–19 weeks’ gestation may be due to increasing fetal swallowing because of the increasing amniotic fluid early in the second trimester of pregnancy. To the best of our knowledge, this is the first study on the reproducibility assessment of fetal movement counting using 4D ultrasound. However, the data and their interpretation in the present study should be taken with some degree of caution because of the small number of subjects studied. Further studies involving a larger sample size are needed to assess the reproducibility of fetal movement counting using 4D ultrasound.

The preimplantation ultrasound (US) refers to targeted imaging of the uterus and adnexa prior to assisted reproductive techniques (ART) to optimize the infertility treatment outcomes. After a thorough evidence based literature review, we propose the use of transvaginal three-dimensional (3D) US during the early follicular phase. A systematic approach for 3D US examination consists of a detailed examination of the uterine shape, size and contour, evaluation of the endometrial thickness, volume, pattern and vascularity, and assessment of the junctional zone regularity, echogenicity and thickness. Uterine anatomy is explored in the coronal plane by simultaneous visualization of the uterine cavity, the external surface of the fundus and cervix. Saline infusion sonogram (SIS) is recommended for patients with increased endometrial volume, abnormal endometrial pattern and irregular uterine cavity shape suggestive of Müllerian duct anomalies or acquired intracavitary abnormalities. Myometrial lesions should be recognized and proper dimensions and locations should be ascertained. Ovarian dimensions and volume are measured and the antral follicle count is recorded. Adnexa are carefully assessed for masses, endometriosis and dilated tubes. Color power Doppler US may be applied to evaluate vascularity of the ovaries and pelvic lesions. Hysterosalpingo-contrast-sonography (Hy-Co-Sy) should be optimally utilized for assessment of tubal patency. Accessibility and mobility of the ovaries should be checked in real time for better planning of the ultrasound-guided oocyte retrieval. The cul-de-sac is assessed for the presence of free fluid or masses.

Three-dimensional ultrasound (3D US) is a modality of choice for prenatal diagnosis of congenital malformations. But 3D-four-dimensional US(4D US) is of utmost importance also to achieve pregnancy. 3D US plays an important role for diagnosis of PCO, to assess ovarian reserve and response and thus to decide optimum stimulation protocols. It adds to the information on follicular maturity and endometrial receptivity, thus improving the chances to achieve pregnancy for patients under treatment for fertility. 3D hystero-contrast-salpingography (HyCoSy) has also proved itself to be one of the best modalities for assessment of tubal patency. In this article, the role of 3D and 4D US is discussed for the following. I. Pretreatment assessment of the females desiring fertility which includes assessment of uterus and fallopian tubes. II. Monitoring of infertile females undergoing treatment. III. Assessment of very early pregnancy – especially in abnormal locations.