In the last few years, technology has progressed to make ultrasound imaging a viable tool. Following Food and Drug Administration (FDA) approval of 3-dimensional ultrasound (3DUS) in November 1997, interest has increased to get more benefits from this new advance.

Scientific advances in imaging processing in recent years have taken ultrasound into the next generation. Until recently, processing speeds were still too slow to offer real time benefit to 3D ultrasound systems. New developments with motion estimation and imaging registration techniques can allow 3D data acquisition to be accomplished without the need for position sensing devices.

The purpose of this article is to review the basics on 3DUS, 3DUS the method and its mains advantages, limitations as well as to mention some frequent pitfalls. It is also aimed to remark important points in pre- and postprocessing.

Two-dimensional ultrasound is commonly used for assessing uterine pathology. Three-dimensional ultrasound is a new imaging modality, which is being introduced into clinical practice. The aim of this paper is addressing the current status of three-dimensional ultrasound in the assessment of uterine pathology.

Two-dimensional ultrasound is commonly used in gynecologic patients. It has been shown to be very useful for diagnosing pelvic pathology in both asymptomatic and symptomatic patients. Three-dimensional ultrasound is a new imaging modality, which is being introduced into clinical practice. Although this technique will not probably replace two-dimensional ultrasound, it is being increasingly used. It has been reported that 3DUS is a very high reproducible technique that may have applications in the field of gynecology. These applications include imaging of the uterus, uterine cavity, adnexa and pelvic floor, as well as very interesting applications using three-dimensional power-Doppler ultrasound. The aim of this paper is addressing some technical features of three-dimensional ultrasound and reviewing its current status in clinical practice.

Ultrasound is widely used in daily clinical obstetrical practice. Many medical indications exist for performing a sonographic examination but, in addition, several researchers have published information on the importance of patients watching the ultrasound monitor during the examination, particularly during three- and fourdimensional (3D/4D) scanning, for maternal-fetal bonding. Furthermore, a certain form of ultrasound, called “entertainment” or “keepsake” ultrasound has flourished, particularly in the United States. While ultrasound is assumed to be completely safe, it is a form of energy and, as such, has effects in tissues it traverses (= bioeffects). The two most important mechanisms for effects are thermal and non-thermal. Nonthermal mechanisms include cavitation, streaming, and even release of free radicals. These two major mechanisms are indicated on-screen by two indices: The thermal index (TI) and the mechanical index (MI). It is important to be aware of these effects to be able to prevent potential harm. Ultrasound machine controls can alter the instrument acoustic energy and hence the exposure but different machines behave differently. Therefore each clinician should know how this occurs in his/her own machine. Unfortunately, it appears the general knowledge in this area is poor and an effort should be made to educate the endusers. Whether 3D/4D enhances parental-fetal bonding is still a matter of discussion.

Fetal cardiac screening is an obligation for everybody performing prenatal ultrasound. The heart, as a small and always moving object, is still the most difficult part of the fetal anatomy evaluation. Knowing this, different methods of improving antenatal screening for congenital heart defects (CHD) were introduced. Spatial temporal image correlation (STIC) is the newest one. Its target was to automatic acquisition of the fetal scan from the abdomen, through 4 chamber view toward the three vessel view and off-line analysis of the anatomy of the fetal cardiovascular system. Is that really possible? Does STIC improve screening of CHD? Would it be helpful in the more precise diagnosis of complicated heart defects? These are still the open questions, which will be discussed in the article.

Fetal neurology is a new challenging field. Brain damage often originates in fetal life. Early identification of this damage has implications for perinatal management; moreover documentation of such lesions is essential in case of litigation. In the last two decades, fetal imaging with 2-dimensional ultrasounds and conventional magnetic resonance imaging have made a major contribution in the identification of classic brain lesions and malformations. However, it is only recently with diffusion weight imaging that the whole spectrum of perinatal white matter injuries has been described in the neonate. The recent advances of 3DUS and 4DUS in exploring fetal motor behavior should support a better clinical description of the full spectrum of fetal damage. New neurological test (KANET) of the fetus recently suggested by us (Kurjak et al 2008) might be helpful in the assessment of fetal neurobehavior.

The evaluation of the fetal face is an important part of every ultrasound examination since detailed facial examination can provide many information alerting the examiner about possible associated anomalies. Face and the brain have the same embryonic origin. By using 2 and 3D ultrasound techniques, it is possible to obtain clear images of different fetal face defects. Incorporation of the 4D ultrasonography made it possible to examine fetal behavior including fetal face movements. In that way using the ultrasound in the examination of the fetal face provides many new information not just about the morphology but also about neurological development and function of the fetal face.

Despite extensive research, cancer of the ovaries remains a major medical problem. The main reason is delay in diagnosis and hence, poor prognosis. This is due to issues in screening and a lack of specific symptoms in early disease. Yearly ultrasound examination and measurement of serum CA125 remain the recommended method despite less than ideal results. Animal research plays a major role in medical research, especially in cancer. Many publications describe the use of ultrasound in cancer research in a large variety of animals. Bmode, spectral and color Doppler have been employed and, more recently, ultrasound contrast agents, both for diagnostic and therapeutic purposes. We have demonstrated that ultrasound can be used to detect early ovarian cancer in the egg-laying chicken. The major advantage is that chickens develop spontaneous ovarian cancer, with a tumor histology that is identical to humans. Furthermore, chickens with ovarian tumors have serum anti-tumor antibodies similar to humans. In addition, the first sign that the egg-laying chicken is going to develop cancer is that it stops laying eggs prematurely.* Thus, a strong biological sign exists to categorize the chicken in a very high risk group, allowing sequential examinations at very close intervals. We have also shown that ultrasound contrast agents may be used for visualization of ovarian vascularity, a step, we hope, in the development of better methods for screening and early diagnosis.

The management of subfertility involves a detailed assessment of the couple to identify factors that may affect or predict the outcome of treatment. Three-dimensional imaging is one of the recent advances in the field of ultrasound which has several obvious benefits that relate to an improved spatial orientation and the demonstration of additional image planes such as the coronal plane. Many clinicians remain unconvinced by its reputed advantages and three-dimensional ultrasound is not without disadvantages. These mainly relate to the cost involved and training requirements. Threedimensional ultrasound imaging is still at a relatively early stage in terms of its role as a day-to-day imaging modality in gynecology and reproductive medicine. Other than its application in the assessment and differentiation of uterine anomalies there is little evidence that three-dimensional ultrasound results in clinically-relevant benefit or negates the need for further investigation. Future work should ensure that three-dimensional ultrasound is compared to conventional imaging in randomized trials where the observer is blinded to the outcome such that its role in reproductive medicine can be truly evaluated in an evidence-based manner.

We compared the hemodynamic profiles of abdominal visceral vessels in physiological and pathological conditions as well as peripheral vessels away from the visceral area.

The resistance index (RI) was monitored in the renal, celiac trunk, gastric, pancreatic and spleen artery linearly in a bi-monthly bases, in 159 physiological pregnancies.

On the other hand an additional group of 47 pregnancies between the 26th and the 40th weeks of gestation were monitored for differences in RI from the renal artery in both right and left kidney. The RI from the right kidney was always lower than in the left kidney, a difference that was nonetheless not statistically significant.

Concerning hemodynamic responses to fetal pathology, kidney hemodynamics were surveyed in two samples of fetuses displaying IUGR. The first sample was made up of a total of 72 fetuses showing IUGR associated with euamnion, while the second sample consisted on 39 IUGR fetuses showing oligohydramnion.

The renal artery in IUGR-euamnion fetuses yielded RI values similar to those recorded from healthy kidneys.

In contrast, in IUGR-oligohydramnion cases, the RI was markedly restrictive when compared to that of healthy and IUGR-euamnion situations.

Besides we investigated in 49 cases the hemodynamic behavior in macrosomic fetuses in diabetes pregnancy, between 32nd to 38th week.

Vascular resistance affecting blood flows in fetal kidneys is lower in macrosomic fetuses with gestational diabetes than in normal gestations with statistical significance.

In cases of kidney parenchyma pathology 49 pregnancies presented severe hydronephrosis, 37 pregnancies had light hydronephrosis and 22 pregnancies were diagnosed as cases of corticomedullar dysplasia associated with oligohydramnion.

RI values from the renal artery were higher in cases of severe hydronephrosis than in cases of light hydronephrosis. This difference was statistically significant.

The RI obtained from cases with mild hydronephrosis was fairly similar to that of healthy kidneys

In contrast, the RI values recorded from fetuses having an association of corticomedullar dysplasia and oligohydramnion were the highest among the three pathological groups.

Regarding splanchnic and other abdominal viscera, celiac trunk's spectral profile were characterized by a low resistance, and showed a gradual increase in diastolic velocity throughout gestation.

The gastric artery displayed a gradually declining vascular resistance through pregnancy.

Hemodynamic records from the pancreatic artery are restrictive over the whole period of gestation and only the maximum systolic peak can be subjected to measurement.

The spleen artery showed a low diastolic resistance which declined markedly through gestation, even in situations of chronic fetal compromise, this artery experienced increased vascularization in response to stress, a vascular trait that was found to be unique for this anatomical area.

The flowmetric resistance in the spleen artery was lower than in the renal artery and than the rest of the abdominal vessels studied.

The femoral artery had a very restrictive hemodynamic profile, which was characterized by the lack of a telediastolic flow.

These data suggests that the fetal blood stores are located in the extremities rather than in visceral areas.

The monitoring of the hemodynamic patterns emerging from the vessel complex studied here, has allowed an insight into the mechanism of vascular centralization in response to perturbing conditions, this mechanism should be regarded as a kind of functional and nutritional autoregulative reaction of the visceral set involved.