Three-dimensional sonography in prenatal diagnosis: a luxury or a necessity?

Rational Use of TVS/Color and 3D in Evaluating Subfertile Women

Infertility is defined as the failure to conceive a desired pregnancy after 12 months of unprotected intercourse and affects approximately 10% of married couples. With recent technological development and proper use of medically assisted reproduction techniques, one half of these couples will become pregnant.

More than any other new method, ultrasound has made significant improvements in the modern management of female infertility. Transvaginal sonography provides the reproductive endocrinologists with a tool that cannot only evaluate normal and stimulated cycles but also assist in follicle aspiration and subsequent transfer of the embryo. The addition of color Doppler capabilities to transvaginal probes permits visualization of small intraovarian and endometrial vessels, allowing depiction of normal and abnormal physiologic changes in the ovary and uterus. This article reviews on the assessment of ovarian, uterine and tubal causes of infertility and on the current and future role of color Doppler and three-dimensional ultrasound in the field of reproductive endocrinology.

Recent advances in ultrasound technology

Technical improvements have made profound changes in diagnostic ultrasound imaging. Some of these changes, such as encoded pulses and receive focusing, occur in the background and are essentially nonadjustable. Others, including harmonics and compounding, are real-time options and are adjustable by the imager. New technologies that offer great promise for improved characterization of lesions include contrast ultrasound and elastography. This article will attempt to update the small animal imager on the clinical applications of these newer technologies.

A comparison of three-dimensional ultrasound, two-dimensional ultrasound and dissections for determination of lesion volume in tendons

The purpose of this work was to evaluate the accuracy and precision of a freehand three-dimensional (3-D) ultrasonography system in the determination of lesion volume in tendons. The accuracy and precision of a 3-D ultrasonography system was assessed by performing repeated measurements on a phantom of known volume. Volume measurements of tendon lesions performed with 3-D ultrasonography were compared with measurements based on a series of two-dimensional (2-D) ultrasound (US) scans and to direct measurements from dissections. A novel method for the creation of tendon lesions in vitro was developed. 3-D US showed excellent precision and accuracy in measurements of the phantom (mean measured volume = 3.76 mL, calculated volume = 3.77 mL, coefficient of variation (CoV) = 0.54%) and good repeatability in the determination of tendon lesions (repeatability coefficient = 0.00047). All three methods examined were repeatable (repeatability coefficient for 2-D US = 0.00032, repeatability coefficient for dissections = 0.00076). However, each of the methods produced different results and no constant relationship could be found between any of the measurement methods. Both 3-D and 2-D US proved to be repeatable techniques for the measurement of the volume of a tendon lesion. Even if they produced different results, each of them can be repeatedly used individually. It was not possible to define which one provided the most accurate value as a result of difficulties encountered in lesion identification on histology, and therefore the lack of a gold standard.

Antenatal diagnosis and prognosis of conjoined twins--a case report

In this report, two conjoined twin cases that were diagnosed at the 19th and 25th week of gestational age are reported. In the first case the pregnancy was terminated because of the very poor prognosis. In the second case the decision was made to continue the pregnancy after counseling explaining the possibility of a separation procedure with good prognosis being carried out after birth. The babies were delivered at 38 weeks of gestation and the separation procedure was carried out at ten months of age without any complications. In selected cases, there is no need to abort, because of the possibility of a separation procedure after birth with good prognosis. Color Doppler ultrasound examination in an early stage of pregnancy in cases of conjoined twin can make it possible to decide which cases are candidates for a separation procedure after birth.

Three-dimensional power Doppler in study of embryonic vasculogenesis

Three-dimensional power Doppler sonography plays an important role in obstetrics, predominantly for assessing the relationship between fetal vascular system and surrounding organs. Presenting volume data in a standard anatomic orientation is valuable for assisting both ultrasonographers and pregnant patients to recognize anatomy more readily. This investigation was designed as an observational cross-sectional study. A group of 25 patients in gestational age of five to eleven weeks were recruited for the study. Architecture of the embryonic vessels was depicted by 3D power flow mapping and analyzed visually. Vascular 3D measurements were done through 3D color/power histogram and expressed by Vascularization Index (VI) and Vascularization Flow Index (VFI). Volume of the embryo increased exponentially throughout the observation period. The VI and VFI showed no change despite an exponential growth of embryonic volume. The findings of our study suggest that in cases of physiologic embryonic vasculogenesis there is a homeostatic steady state between tissue demands and blood supply given through the vascular network.

Limb deformities and three-dimensional ultrasound

AIM

To assess the ability of three-dimensional (3D) ultrasonography for improvement of antenatal detection of limb deformities.

METHODS

347 patients were selected from a routine outpatient clinic or sent for supervision from other units because of suspected anomalies of fetal extremities. 3D ultrasound devices used in the study were Combison 530D and Voluson 530D MT (Kretztechnik, Zipf, Austria) with a 3-5 MHz annular array transducer for three-dimensional volume scanning.

RESULTS

In 41 of 347 patients the initial diagnosis was suspected by two-dimensional sonography (gestational age 18-32 weeks). In 28 of 41 suspected cases the diagnosis of abnormalities was determined after examination by 3D sonography: 17/28 clubfoot, 3/28 hand-polydactily, 2/28 upper limb contractures, 1/28 lower limb contractures, 4/28 micromelia within the syndrome of skeletal dysplasia. In 13 of 41 suspected cases, normal anatomy was confirmed using 3D sonography.

CONCLUSION

Three-dimensional sonography is the "method of choice" for the detection of an isolated defect of a single limb, developmental or positional deformations and minor defects of hands and feet. Surface-mode reconstruction of the complete limb and transparent-view reconstruction of the entire skeletal structure are effective technical advantages enabling a completely new visual perception of the unborn baby.

Three-dimensional (3D) ultrasound--a useful imaging technique in the assessment of neonatal brain

Clinical application of ultrasound began about fifty years ago. From one-dimensional A-mode, through two-dimensional real time and Doppler examinations, a new era in clinical ultrasonography then began in the late eighties. Development of computer technology enabled introduction of 3D ultrasonography into clinical practice. In obstetrics ultrasound revolutionized fetal follow-up, but it was as important for the detection of intracranial pathology during the neonatal period and infancy. Two-dimensional real time ultrasonography was [table: see text] an exciting method that changed our understanding of the prevalence and pathophysiology of brain pathology in premature and term infants. Will application of 3D ultrasonography bring any substantial improvement to neuroimaging diagnostics in the newborn period? This article attempts to find the answer to this question, despite the limitations set by the short period of application of 3D neurosonography in neonates. The advantages of 3D brain ultrasonography application in neonates are: quicker and observer independent data acquisition, the possibility of off-line data analysis, projection of 3D data on a 2D plane with volumetric, color and power Doppler studies. Unavailability of equipment is the main reason why 3D ultrasonography was performed in only half of the newborns in whom it was indicated. Cost of equipment prevents introduction of 3D as a standard diagnostic procedure in neonates, although its diagnostic value is indisputable.

The assessment of fetal brain morphology and circulation by transvaginal 3D sonography and power Doppler

OBJECTIVE

The objective of this article is to describe the use of transvaginal 3D ultrasound in prenatal neuroimaging and to investigate its clinical usefulness.

METHODS

Firstly, 18 fetuses with hydrocephalus, ventriculomegaly and/or space occupying lesion were examined by transvaginal 3D sonography, and fetal CNS abnormalities were evaluated. Multiplanar image analysis and volumetric assessment were performed off-line. Longitudinal volume changes of target structure were evaluated, and usefulness of transvaginal 3D ultrasound was evaluated. Secondly, in 56 normal cephalic fetuses of between 18 and 32 weeks, 3D Doppler volume acquisition and reconstruction of the intracranial vascular structure were performed.

RESULTS

Longitudinal changing appearance in the same cutting section of the enlarged ventricle or cystic lesion could be demonstrated in all cases and volumetric assessment was also successful in all cases. Longitudinal objective data were useful in the brain assessment, consultation and counselling. 3D Doppler acquisition time was 5.6-26 seconds and symmetrical 3D reconstruction was successful in 51.8%.

CONCLUSION

Transvaginal 3D imaging technology provides us with not only comprehensive intracranial images in exactly the right sections, but also with objective volume data. Prenatal information with objective data analyses is useful in consultation for both specialists and parents, and leads to proper management of CNS diseases.

The role of three-dimensional ultrasound in obstetrics

Three-dimensional ultrasound is a relatively new imaging modality with several potential advantages over conventional two-dimensional sonography. There is now increasing evidence that three-dimensional ultrasound can in many ways assist in the examination of the fetus. The enthusiasm generated by some groups, however, is not universally shared. It is the aim of this review to summarize the contemporary role of three-dimensional ultrasound in obstetric sonography by giving a critical appraisal of the relevant literature published recently, with emphasis on first and second trimester anatomy and fetal organ and placenta volumetry.

Three-dimensional ultrasonography in early pregnancy

Three-dimensional ultrasound was introduced into clinical use over a decade ago. Early attempts on three-dimensional ultrasound were primitive and limited to experimental use only. Recently, it was used as a powerful tool to display three-dimensional fetal appearance and assess normal and pathological conditions. Because of the improvement in image resolution and reconstruction speed, three-dimensional ultrasound is now more and more popular in many centers, and used commonly as an adjunct in prenatal diagnosis. Indeed, a skillful sonographer may usually make the correct diagnosis of fetal anomaly with simply two-dimensional ultrasound. Nonetheless, the situation is gradually changing, because some anomalies have been diagnosed only based on the findings of three-dimensional ultrasound. In spite of that, the application of three-dimensional ultrasound is still less discussed in early pregnancy. In this article, the authors clarify the capability of three-dimensional ultrasound in different anatomic areas, and catalog its clinical merits in the early pregnancy to date. We also present the safety guidelines for its use in the first trimester.