Three-dimensional ultrasound evaluation of short-rib polydactyly syndrome type II in the second trimester: a case report

Incorporating 3D and 4D Ultrasound into Clinical Practice

3D ultrasound has been slow to make significant impact in clinical practice. In a large part, this is because 2D ultrasound is of such superior quality that sonographers have not seen any gain in adopting the new technology. More recently, however, diverse application of 3D technology has taken place in many branches of medicine, with obstetrics and gynaecology at the forefront. Several manufacturers now produce machines of remarkable sophistication and utility. Hardware and software have been integrated to allow the release of information from the ultrasound examination that has hitherto not been possible. In addition, virtual real time 3D images (4D ultrasound) have captured the imagination of both public and media. We report our preliminary clinical experience with 3 and 4D ultrasound in a limited clinical environment. While not suitable for wide scale application at present, we believe this technology has inherent advantages that will secure its clinical role and that this role will widen rapidly in the near future.

Three-dimensional ultrasound of the fetus: how does it help?

Three-dimensional ultrasonography (3-D US) was introduced to the field of fetal imaging in the early 1990s. Since then several publications have described potential applications for the diagnosis of congenital malformations as well as organ volumetry. This article reviews basic principles of 3-D US as well as its clinical applicability to prenatal diagnosis of abnormalities involving the face, spine and skeletal system, as well as potential applications of 3-D US for fetal cardiovascular and neuroimaging. Limitations related to motion artifacts, acoustic shadowing and barriers to clinical implementation of 3-D US in clinical practice are addressed.

Advances in evaluating the fetal skeleton

In this review, we discuss aspects of the prenatal diagnosis of fetal skeletal malformations, concentrating on the advantages offered by different imaging techniques and the approaches that are of value in evaluating a suspected skeletal dysplasia. We also briefly address the findings in some of the commoner malformations of the fetal skeleton that may be encountered.

Prenatal diagnosis of skeletal dysplasias: contribution of three-dimensional computed tomography

OBJECTIVE

To describe the contribution of 3-dimensional computed tomography (3D-CT) in the prenatal diagnosis of skeletal dysplasias (SD) in a cohort of patients with inconclusive diagnosis by ultrasound (US).

METHODS

Between May 2007 and February 2010, six pregnant women with suspected fetal SD on US examination but with no specific diagnosis were studied with 3D-CT. The images were evaluated by a multidisciplinary team who proposed a likely diagnosis. Further postnatal workup included clinical and radiological evaluation in all cases. Prenatal and postnatal diagnoses were compared.

RESULTS

The use of 3D-CT provided a precise diagnosis confirmed postnatally in 5/6 patients. These included osteogenesis imperfecta type II (n = 2), osteogenesis imperfecta type III (n = 1), chondrodysplasia punctata (n = 1) and thanatophoric dysplasia type I (n = 1). A precise diagnosis could not be made in 1 case - either pre- or postnatally.

CONCLUSION

Prenatal 3D-CT contributed to the diagnosis of the specific fetal SD in the majority of these cases. 3D-CT may have a complementary role to US where fetal SD is suspected, but no specific diagnosis can be made using US alone. Further studies on clinical performance and risk-benefit analysis are needed.

Suspected fetal skeletal malformations or bone diseases: how to explore

Skeletal dysplasias are a heterogeneous and complex group of conditions that affect bone growth and development and result in various anomalies in shape and size of the skeleton. Although US has proved reliable for the prenatal detection of skeletal abnormalities, the precise diagnosis of a dysplasia is often difficult to make before birth (especially in the absence of a familial history) due to their various phenotypic presentations, the variability in the time at which they manifest and often, the lack of precise molecular diagnosis. In addition to the accuracy of the antenatal diagnosis, it is very important to establish a prognosis. This is a clinically relevant issue as skeletal dysplasias may be associated with severe disability and may even be lethal. We will therefore describe the respective role of two-dimensional (2-D) US, three-dimensional (3-D) US and CT in the antenatal assessment of skeletal malformations.

Three-dimensional ultrasound imaging

This review is about the development of three-dimensional (3D) ultrasonic medical imaging, how it works, and where its future lies. It assumes knowledge of two-dimensional (2D) ultrasound, which is covered elsewhere in this issue. The three main ways in which 3D ultrasound may be acquired are described: the mechanically swept 3D probe, the 2D transducer array that can acquire intrinsically 3D data, and the freehand 3D ultrasound. This provides an appreciation of the constraints implicit in each of these approaches together with their strengths and weaknesses. Then some of the techniques that are used for processing the 3D data and the way this can lead to information of clinical value are discussed. A table is provided to show the range of clinical applications reported in the literature. Finally, the discussion relating to the technology and its clinical applications to explain why 3D ultrasound has been relatively slow to be adopted in routine clinics is drawn together and the issues that will govern its development in the future explored.

Three-dimensional ultrasound in prenatal diagnosis

PURPOSE OF REVIEW

Several technological advances have greatly improved three-dimensional sonography, which have improved acquisition and display capabilities. This review describes these technical changes as well as current applications of 3D sonography in prenatal diagnosis.

RECENT FINDINGS

Recently published papers have emphasized the potential of getting a precise 'any plane of choice' from a three-dimensional volume, as a new way of scanning, based on the off-line analysis of a volume dataset. Surface mode has been used to demonstrate malformations and genetic diseases. The maximum rendering mode, which highlights bones, has great potential for imaging the nasal bones and the frontal bones with the metopic suture. Organ volume can be measured, but the utility of this in clinical practice remains to be determined. Three-dimensional ultrasound needs to be standardized.

SUMMARY

Three-dimensional ultrasonography is the most rapidly developing technique in fetal imaging. New features will permit the transition from the era of 'sonography in two-dimensional planes' to 'volume ultrasound'.

Three and four-dimensional ultrasound in obstetrics and gynecology

PURPOSE OF REVIEW

Developments in ultrasound in general, but even more so in three-dimensional ultrasound, parallel the growth in computing power and speed of computer technology. It is not surprising, therefore, that three-dimensional ultrasound technology is constantly evolving at a fast pace. The purpose of this article is to provide enhanced diagnostic capabilities for the obstetrical and gynecologic provider.

RECENT FINDINGS

The most recent advances in three-dimensional ultrasound have to do with two main features. First, an increasingly fast acquisition speed, enabling quick sequences of fast moving organs such as the heart to be captured. Second, the increasing number of different display modalities, making understanding and analysis of normal anatomy and pathology easier for clinicians.

SUMMARY

This article highlights a selected number of clinical situations in which three-dimensional ultrasound meaningfully enhances the contribution of this fast evolving diagnostic imaging tool.

A guide to the recognition of skeletal disorders in the fetus

The discovery of fetal skeletal abnormality on prenatal US mandates an extended study of the fetus. This extended examination includes specific views and measurements of the fetal skeleton. Lethality can be predicted if severe pulmonary hypoplasia is present. Specific diagnosis of a fetal osteochondrodysplasia is difficult; a collaborative approach among obstetric, neonatal and genetic services is necessary to provide the parents with all available information regarding the pregnancy. Pediatric radiologists who have experience in radiologic assessment of osteochondrodystrophies of infants and children can provide expertise in this area.

Three-dimensional multiplanar ultrasound in a limb-body wall complex fetus: clinical evidence for counseling

A rare dysmorphologic fetal anomaly at the 17th week of gestation was suspected during a second trimester routine scan for fetal and maternal screening data. First findings were significant for a severe abdominal wall defect, limb and foot compromised positions. Fetal biometry was appropriate in biparietal diameter and head circumference measurements; the long upper bones were normal both for length and development. The patient was referred to a prenatal unit to complete the sonographic diagnosis. Two- and three-dimensional sonographic investigations were performed and techniques were complementary for fetal maldevelopment specification. Limb-body wall complex with lumbosacral spine torsion and lower limbs with severely abnormal features were identified. With 2D color Doppler, a heart defect was confirmed and the umbilical cord was missing from the amniotic cavity. An invasive procedure by amniocentesis was made to ascertain alpha-fetoprotein levels and fetal karyotype. Following parental counseling, pregnancy was terminated and feto-pathological examination confirmed the sonographic diagnosis. The 17-week fetus affected by limb-body wall complex is reported herein; 2D and 3D scans of the fetus identified organ displacement due to a combination of very early events.

Three- and 4-dimensional ultrasound in obstetric practice: does it help?

OBJECTIVE

The purpose of this article was to review the published literature on 3-dimensional ultrasound (3DUS) and 4-dimensional ultrasound (4DUS) in obstetrics and determine whether 3DUS adds diagnostic information to what is currently provided by 2-dimensional ultrasound (2DUS) and, if so, in what areas.

METHODS

A PubMed search was conducted for articles reporting on the use of 3DUS or 4DUS in obstetrics. Seven-hundred six articles were identified, and among those, 525 were actually related to the subject of this review. Articles describing technical developments, clinical studies, reviews, editorials, and studies on fetal behavior or maternal-fetal bonding were reviewed.

RESULTS

Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, especially facial clefts. There is also evidence that 3DUS provides additional diagnostic information in neural tube defects and skeletal malformations. Large studies comparing 2DUS and 3DUS for the diagnosis of congenital anomalies have not provided conclusive results. Preliminary evidence suggests that sonographic tomography may decrease the examination time of the obstetric ultrasound examination, with minimal impact on the visualization rates of anatomic structures.

CONCLUSIONS

Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, evaluation of neural tube defects, and skeletal malformations. Additional research is needed to determine the clinical role of 3DUS and 4DUS for the diagnosis of congenital heart disease and central nervous system anomalies. Future studies should determine whether the information contained in the volume data set, by itself, is sufficient to evaluate fetal biometric measurements and diagnose congenital anomalies.

Three-Dimensional Ultrasound in Small Parts

For longer than 40 years, ultrasound (US) has been a widely used imaging tool in medical practice, which has proved helpful for the diagnosis and staging of diseases. Although three-dimensional ultrasound (3D) US has been available for more than 10 years, it was only through the development of the most recent computer technologies and its adaptation to ultrasound systems, that 3D US has become able to achieve the high level of sensitivity and performance necessary to be considered seriously in clinical practice. 3D US is rapidly turning into a technology with an ever-increasing range of applications in numerous fields because, among other reasons, it helps overcome some of the key limitations related to two-dimensional imaging. 3D US can be used in ultrasonography for small parts, among other medical areas. The assessment of the testicle, parotid, thyroid and parathyroid glands is properly achieved. The multiplanar presentation and niche mode are quite useful to determine the extension--inside or outside the organs-, of nodules, cysts or tumors. The volume measurement is better assessed with 3D US and given this, we can perform studies that follow growth in order to decide medical or surgical treatment. The VOCAL makes it possible to obtain a proper after-treatment follow-up of focal disorders in these small organs. Neovascularization is clearly viewed with 3D US and probably can suggest malignant origin of a neoplasm. 3D US offers a more comprehensive image of anatomical structures and pathological conditions and also permits to observe the exact spatial relationships. We are aware more studies are needed to demonstrate specificity and sensibility of 3D US in particular clinical conditions, not only in small parts but also is some other non-Ob/Gyn applications.

Craniofacial dysmorphology and three-dimensional ultrasound: a prospective study on practicability for prenatal diagnosis

OBJECTIVE

The aim of this study is to compare two-dimensional and three-dimensional ultrasound for the visualization and diagnosis of craniofacial dysmorphism.

METHODS

In this prospective study, we performed three-dimensional (3D) ultrasound following good-quality two-dimensional (2D) ultrasound in an at-risk population. Findings from 2D and 3D examination were noted.

RESULTS

Our series included 41 patients. In 20 cases, 3D performed better than 2D, and in two cases 2D was more informative. In 9 cases, there was no difference between the performance of the two, and in two cases both 2D and 3D gave inadequate results. However, in 7 cases 3D images could not be obtained.

CONCLUSION

Although it is rarely decisive, 3D ultrasound is of interest when it comes to the precise description of craniofacial dysmorphisms and the study of the fetal ears.