Imaging of the human embryo with magnetic resonance imaging microscopy and high-resolution transvaginal 3-dimensional sonography: human embryology in the 21st century

The biophysics of water in cell biology: perspectives on a keystone for both marine sciences and cancer research

The biophysics of water, has been debated over more than a century. Although its importance is still underestimated, significant breakthroughs occurred in recent years. The influence of protein condensation on water availability control was documented, new findings on water-transport proteins emerged, and the way water molecules rearrange to minimize free energy at interfaces was deciphered, influencing membrane thermodynamics. The state of knowledge continued to progress in the field of deep-sea marine biology, highlighting unknown effects of high hydrostatic pressure and/or temperature on interactions between proteins and ligands in extreme environments, and membrane structure adaptations. The role of osmolytes in protein stability control under stress is also discussed here in relation to fish egg hydration/buoyancy. The complexity of water movements within the cell is updated, all these findings leading to a better view of their impact on many cellular processes. The way water flow and osmotic gradients generated by ion transport work together to produce the driving force behind cell migration is also relevant to both marine biology and cancer research. Additional common points concern water dynamic changes during the neoplastic transformation of cells and tissues, or embryo development. This could improve imaging techniques, early cancer diagnosis, and understanding of the molecular and physiological basis of buoyancy for many marine species.

Fetal face shape analysis from prenatal 3D ultrasound images

3D ultrasound imaging of fetal faces has been predominantly confined to qualitative assessment. Many genetic conditions evade diagnosis and identification could assist with parental counselling, pregnancy management and neonatal care planning. We describe a methodology to build a shape model of the third trimester fetal face from 3D ultrasound and show how it can objectively describe morphological features and gestational-age related changes of normal fetal faces. 135 fetal face 3D ultrasound volumes (117 appropriately grown, 18 growth-restricted) of 24-34 weeks gestation were included. A 3D surface model of each face was obtained using a semi-automatic segmentation workflow. Size normalisation and rescaling was performed using a growth model giving the average size at every gestation. The model demonstrated a similar growth rate to standard head circumference reference charts. A landmark-free morphometry model was estimated to characterize shape differences using non-linear deformations of an idealized template face. Advancing gestation is associated with widening/fullness of the cheeks, contraction of the chin and deepening of the eyes. Fetal growth restriction is associated with a smaller average facial size but no morphological differences. This model may eventually be used as a reference to assist in the prenatal diagnosis of congenital anomalies with characteristic facial dysmorphisms.

Three-dimensional visualization and quantitative analysis of embryonic and fetal thigh muscles using magnetic resonance and phase-contrast X-ray imaging

The musculoskeletal system around the human hip joint has acquired a suitable structure for erect bipedal walking. However, little is known about the process of separation and maturation of individual muscles during the prenatal period, when muscle composition is acquired. Understanding the maturation process of the normal musculoskeletal system contributes to elucidating the acquisition of bipedal walking in humans and to predicting normal growth and detecting congenital muscle disorders and anomalies. In this study, we clarify the process of thigh muscle maturation from the embryonic stage to the mid-fetal stage using serial sections, phase-contrast X-ray computed tomography, and magnetic resonance imaging. We also provide a 4D atlas of human thigh muscles between 8 and 23 weeks of gestation. As a result, we first show that muscle separation in the lower thigh tends to progress from the superficial to the deep layers and that all musculoskeletal components are formed by Carnegie Stage 22. Next, we show that femur and muscle volume grow in correlation with crown-rump length. Finally, we show that the anterior, abductor, and posterior muscle groups in the thigh contain a high percentage of monoarticular muscle volume by the end of the embryonic period. This ratio approaches that of adult muscle composition during normal early fetal development and is typical of bipedal walking. This study of fetal muscle composition suggests that preparation for postnatal walking may begin in early fetal period.

Extended reality visualization of medical museum specimens: Online presentation of conjoined twins curated by Dr. Jacob Henle between 1844-1852

Background:

The purpose of this study is to characterize a full-term conjoined twins’ cadaver curated by Dr. Jacob Henle sometime between 1844 and 1852 and demonstrate digital distribution of an old and rare medical museum specimen using an extended reality (XR) model workflow.

Methods:

The cadaver (Preparation 296) is in the Department of Anatomy and Cell Biology at the University of Heidelberg. An XR display workflow comprises image capture, segmentation, and visualization using CT/MR scans derived from the cadaver. Online radiology presentation to medical students focuses on diagnostic characteristics of anatomical systems depicted with XR models.

Results:

Developmental defects in Preparation 296 include duplicated supradiaphragmatic structures and abnormal osteological features. Subdiaphragmatically, the gut is continuous on the right, but terminates at the distal esophagus on the left. One large liver occupies the abdomen with one spleen located on the left side. Observations suggest duplication of the primitive streak and separate notochords rostrally. Duplication occurs near the yolk sac and involves midgut formation while secondary midline fusion of the upper extremities and ribs likely results from the proximity of the embryos during development. Medical students access the model with device agnostic software during the curricular topic “Human Body Plan” that includes embryology concepts covering mechanisms of twinning.

Conclusions:

The workflow enables ease-of-access XR visualizations of an old and rare museum specimen. This study also demonstrates digital distribution and utilization of XR models applicable to embryology education.

Watching the embryo: Evolution of the microscope for the study of embryogenesis

Embryos and microscopes share a long, remarkable history and biologists have always been intrigued to watch how embryos develop under the microscope. Here we discuss the advances in microscopy which have greatly influenced our current understanding of embryogenesis. We highlight the evolution of microscopes and the optical technologies that have been instrumental in studying various developmental processes. These imaging modalities provide mechanistic insights into the dynamic cellular and molecular events which drive lineage commitment and morphogenetic changes in the developing embryo. We begin the journey with a brief history of microscopy to study embryos. First, we review the principles and optics of light, fluorescence, confocal, and electron microscopy which have been key techniques for imaging cellular and molecular events during embryonic development. Next, we discuss recent key imaging modalities such as light-sheet microscopy, which are suitable for whole embryo imaging. Further, we highlight imaging techniques like multiphoton and super resolution microscopy for beyond light diffraction limit, high resolution imaging. Lastly, we review some of the scattering-based imaging methods and techniques used for imaging human embryos.

Development of the sympathetic trunks in human embryos

Although the development of the sympathetic trunks was first described >100 years ago, the topographic aspect of their development has received relatively little attention. We visualised the sympathetic trunks in human embryos of 4.5–10 weeks post‐fertilisation, using Amira 3D‐reconstruction and Cinema 4D‐remodelling software. Scattered, intensely staining neural crest‐derived ganglionic cells that soon formed longitudinal columns were first seen laterally to the dorsal aorta in the cervical and upper thoracic regions of Carnegie stage (CS)14 embryos. Nerve fibres extending from the communicating branches with the spinal cord reached the trunks at CS15‐16 and became incorporated randomly between ganglionic cells. After CS18, ganglionic cells became organised as irregular agglomerates (ganglia) on a craniocaudally continuous cord of nerve fibres, with dorsally more ganglionic cells and ventrally more fibres. Accordingly, the trunks assumed a “pearls‐on‐a‐string” appearance, but size and distribution of the pearls were markedly heterogeneous. The change in position of the sympathetic trunks from lateral (para‐aortic) to dorsolateral (prevertebral or paravertebral) is a criterion to distinguish the “primary” and “secondary” sympathetic trunks. We investigated the position of the trunks at vertebral levels T2, T7, L1 and S1. During CS14, the trunks occupied a para‐aortic position, which changed into a prevertebral position in the cervical and upper thoracic regions during CS15, and in the lower thoracic and lumbar regions during CS18 and CS20, respectively. The thoracic sympathetic trunks continued to move further dorsally and attained a paravertebral position at CS23. The sacral trunks retained their para‐aortic and prevertebral position, and converged into a single column in front of the coccyx. Based on our present and earlier morphometric measurements and literature data, we argue that differential growth accounts for the regional differences in position of the sympathetic trunks.

Extrinsic innervation of the pelvic organs in the lesser pelvis of human embryos

Realistic models to understand the developmental appearance of the pelvic nervous system in mammals are scarce. We visualized the development of the inferior hypogastric plexus and its preganglionic connections in human embryos at 4-8 weeks post-fertilization, using Amira 3D reconstruction and Cinema 4D-remodelling software. We defined the embryonic lesser pelvis as the pelvic area caudal to both umbilical arteries and containing the hindgut. Neural crest cells (NCCs) appeared dorsolateral to the median sacral artery near vertebra S1 at ~5 weeks and had extended to vertebra S5 1 day later. Once para-arterial, NCCs either formed sympathetic ganglia or continued to migrate ventrally to the pre-arterial region, where they formed large bilateral inferior hypogastric ganglionic cell clusters (IHGCs). Unlike more cranial pre-aortic plexuses, both IHGCs did not merge because the 'pelvic pouch', a temporary caudal extension of the peritoneal cavity, interposed. Although NCCs in the sacral area started to migrate later, they reached their pre-arterial position simultaneously with the NCCs in the thoracolumbar regions. Accordingly, the superior hypogastric nerve, a caudal extension of the lumbar splanchnic nerves along the superior rectal artery, contacted the IHGCs only 1 day later than the lumbar splanchnic nerves contacted the inferior mesenteric ganglion. The superior hypogastric nerve subsequently splits to become the superior hypogastric plexus. The IHGCs had two additional sources of preganglionic innervation, of which the pelvic splanchnic nerves arrived at ~6.5 weeks and the sacral splanchnic nerves only at ~8 weeks. After all preganglionic connections had formed, separate parts of the inferior hypogastric plexus formed at the bladder neck and distal hindgut.

Development of extrinsic innervation in the abdominal intestines of human embryos

Compared to the intrinsic enteric nervous system (ENS), development of the extrinsic ENS is poorly documented, even though its presence is easily detectable with histological techniques. We visualised its development in human embryos and foetuses of 4–9.5 weeks post‐fertilisation using Amira 3D‐reconstruction and Cinema 4D‐remodelling software. The extrinsic ENS originated from small, basophilic neural crest cells (NCCs) that migrated to the para‐aortic region and then continued ventrally to the pre‐aortic region, where they formed autonomic pre‐aortic plexuses. From here, nerve fibres extended along the ventral abdominal arteries and finally connected to the intrinsic system. Schwann cell precursors (SCPs), a subgroup of NCCs that migrate on nerve fibres, showed region‐specific differences in differentiation. SCPs developed into scattered chromaffin cells of the adrenal medulla dorsolateral to the coeliac artery (CA) and into more tightly packed chromaffin cells of the para‐aortic bodies ventrolateral to the inferior mesenteric artery (IMA), with reciprocal topographic gradients between both fates. The extrinsic ENS first extended along the CA and then along the superior mesenteric artery (SMA) and IMA 5 days later. Apart from the branch to the caecum, extrinsic nerves did not extend along SMA branches in the herniated parts of the midgut until the gut loops had returned in the abdominal cavity, suggesting a permissive role of the intraperitoneal environment. Accordingly, extrinsic innervation had not yet reached the distal (colonic) loop of the midgut at 9.5 weeks development. Based on intrinsic ENS‐dependent architectural remodelling of the gut layers, extrinsic innervation followed intrinsic innervation 3–4 Carnegie stages later.

The development of the cloaca in the human embryo

Subdivision of cloaca into urogenital and anorectal passages has remained controversial because of disagreements about the identity and role of the septum developing between both passages. This study aimed to clarify the development of the cloaca using a quantitative 3D morphological approach in human embryos of 4–10 post‐fertilisation weeks. Embryos were visualised with Amira 3D‐reconstruction and Cinema 4D‐remodelling software. Distances between landmarks were computed with Amira3D software. Our main finding was a pronounced difference in growth between rapidly expanding central and ventral parts, and slowly or non‐growing cranial and dorsal parts. The entrance of the Wolffian duct into the cloaca proved a stable landmark that remained linked to the position of vertebra S3. Suppressed growth in the cranial cloaca resulted in an apparent craniodorsal migration of the entrance of the Wolffian duct, while suppressed growth in the dorsal cloaca changed the entrance of the hindgut from cranial to dorsal on the cloaca. Transformation of this ‘end‐to‐end’ into an ‘end‐to‐side’ junction produced temporary ‘lateral (Rathke's) folds’. The persistent difference in dorsoventral growth straightened the embryonic caudal body axis and concomitantly extended the frontally oriented ‘urorectal (Tourneux's) septum’ caudally between the ventral urogenital and dorsal anorectal parts of the cloaca. The dorsoventral growth difference also divided the cloacal membrane into a well‐developed ventral urethral plate and a thin dorsal cloacal membrane proper, which ruptured at 6.5 weeks. The expansion of the pericloacal mesenchyme followed the dorsoventral growth difference and produced the genital tubercle. Dysregulation of dorsal cloacal development is probably an important cause of anorectal malformations: too little regressive development may result in anorectal agenesis, and too much regression in stenosis or atresia of the remaining part of the dorsal cloaca.

Three-dimensional models of the segmented human fetal brain generated by magnetic resonance imaging

Recent advances in imaging technology have enabled us to obtain more detailed images of the human fetus in a nondestructive and noninvasive manner. Through detailed images, elaborate three-dimensional (3D) models of the developing brain can be reconstructed. The segmentation of the developing brain has been determined by serial sections. Therefore, in this study, we attempted to develop a 3D model of the fetal brain using magnetic resonance image (MRI). MR images from 19 specimens (11 embryonic specimens and eight fetal specimens from 5.2 to 225 mm in crown rump length) were used to reconstruct 3D models of regionalized developing brains. From this analysis, we succeeded in registering a maximum of nine landmarks on MR images and reconstructing 19 sequential models of the regionalized developing brain. To confirm the validity of the landmarks, we also compared our results with three serial sections from the Kyoto Collection; the same morphological characteristics were observed on both serial sections and MRI. The morphological minutiae could be found on MR images, and regionalized models of the developing brain could be reconstructed. These results will be useful for clinical diagnosis of living fetuses in utero.

The fate of the vitelline and umbilical veins during the development of the human liver

Differentiation of endodermal cells into hepatoblasts is well studied, but the remodeling of the vitelline and umbilical veins during liver development is less well understood. We compared human embryos between 3 and 10 weeks of development with pig and mouse embryos at comparable stages, and used Amira 3D reconstruction and Cinema 4D remodeling software for visualization. The vitelline and umbilical veins enter the systemic venous sinus on each side via a common entrance, the hepatocardiac channel. During expansion into the transverse septum at Carnegie Stage (CS)12 the liver bud develops as two dorsolateral lobes or 'wings' and a single ventromedial lobe, with the liver hilum at the intersection of these lobes. The dorsolateral lobes each engulf a vitelline vein during CS13 and the ventromedial lobe both umbilical veins during CS14, but both venous systems remain temporarily identifiable inside the liver. The dominance of the left-sided umbilical vein and the rightward repositioning of the sinuatrial junction cause de novo development of left-to-right shunts between the left umbilical vein in the liver hilum and the right hepatocardiac channel (venous duct) and the right vitelline vein (portal sinus), respectively. Once these shunts have formed, portal branches develop from the intrahepatic portions of the portal vein on the right side and the umbilical vein on the left side. The gall bladder is a reliable marker for this hepatic vascular midline. We found no evidence for large-scale fragmentation of embryonic veins as claimed by the 'vestigial' theory. Instead and in agreement with the 'lineage' theory, the vitelline and umbilical veins remained temporally identifiable inside the liver after being engulfed by hepatoblasts. In agreement with the 'hemodynamic' theory, the left-right shunts develop de novo.

Closure of the vertebral canal in human embryos and fetuses

The vertebral column is the paradigm of the metameric architecture of the vertebrate body. Because the number of somites is a convenient parameter to stage early human embryos, we explored whether the closure of the vertebral canal could be used similarly for staging embryos between 7 and 10 weeks of development. Human embryos (5-10 weeks of development) were visualized using Amira 3D^® reconstruction and Cinema 4D^® remodelling software. Vertebral bodies were identifiable as loose mesenchymal structures between the dense mesenchymal intervertebral discs up to 6 weeks and then differentiated into cartilaginous structures in the 7th week. In this week, the dense mesenchymal neural processes also differentiated into cartilaginous structures. Transverse processes became identifiable at 6 weeks. The growth rate of all vertebral bodies was exponential and similar between 6 and 10 weeks, whereas the intervertebral discs hardly increased in size between 6 and 8 weeks and then followed vertebral growth between 8 and 10 weeks. The neural processes extended dorsolaterally (6th week), dorsally (7th week) and finally dorsomedially (8th and 9th weeks) to fuse at the midthoracic level at 9 weeks. From there, fusion extended cranially and caudally in the 10th week. Closure of the foramen magnum required the development of the supraoccipital bone as a craniomedial extension of the exoccipitals (neural processes of occipital vertebra 4), whereas a growth burst of sacral vertebra 1 delayed closure until 15 weeks. Both the cranial- and caudal-most vertebral bodies fused to form the basioccipital (occipital vertebrae 1-4) and sacrum (sacral vertebrae 1-5). In the sacrum, fusion of its so-called alar processes preceded that of the bodies by at least 6 weeks. In conclusion, the highly ordered and substantial changes in shape of the vertebral bodies leading to the formation of the vertebral canal make the development of the spine an excellent, continuous staging system for the (human) embryo between 6 and 10 weeks of development.

Metacarpal Bone Plane Examination by Ultrasonography for the Diagnosis of Fetal Forearm and Hand Deformity

We explored the value of the metacarpal bone plane in screening for serious fetal forearm and hand deformities, excluding simple polydactyly and dactylion deformity, by ultrasonographic examination. Observed the second to fifth metacarpal bone plane of fetuses in 20,139 pregnant women at a gestational age of 16 to 30 weeks in The International Peace Maternity & Child Health Hospital of China Welfare Institute (IPMCH). There was a total 138 cases of fetal forearm and/or hand deformity among the 20,139 pregnant women. Of these, 134 cases were diagnosed, 4 cases were not diagnosed, and 1 case was misdiagnosed. Among the 134 diagnosed cases, there were 19 cases of hand absence, 5 cases of cleft hand, 13 cases of ectrodactyly, 26 cases of radius absence, 9 cases of forearm and hand dysplasia, 55 cases of thanatophoric dysplasia, 6 cases of wrist joint dysplasia, and 1 case of forearm amputation deformity. The deformity rate was 0.76%, the diagnostic coincidence rate was 99.97%, the sensitivity was 97.10%, the specificity was 99.99%, and the false negative rate was 2.9%. As such, careful observation of the metacarpal bone plane can be used increase the diagnosis rate of fetal forearm and hand deformity.

Development of the ventral body wall in the human embryo

Migratory failure of somitic cells is the commonest explanation for ventral body wall defects. However, the embryo increases ~ 25-fold in volume in the period that the ventral body wall forms, so that differential growth may, instead, account for the observed changes in topography. Human embryos between 4 and 10 weeks of development were studied, using amira reconstruction and cinema 4D remodeling software for visualization. Initially, vertebrae and ribs had formed medially, and primordia of sternum and hypaxial flank muscle primordium laterally in the body wall at Carnegie Stage (CS)15 (5.5 weeks). The next week, ribs and muscle primordium expanded in ventrolateral direction only. At CS18 (6.5 weeks), separate intercostal and abdominal wall muscles differentiated, and ribs, sterna, and muscles began to expand ventromedially and caudally, with the bilateral sternal bars fusing in the midline after CS20 (7 weeks) and the rectus muscles reaching the umbilicus at CS23 (8 weeks). The near-constant absolute distance between both rectus muscles and approximately fivefold decline of this distance relative to body circumference between 6 and 10 weeks identified dorsoventral growth in the dorsal body wall as determinant of the 'closure' of the ventral body wall. Concomitant with the straightening of the embryonic body axis after the 6th week, the abdominal muscles expanded ventrally and caudally to form the infraumbilical body wall. Our data, therefore, show that the ventral body wall is formed by differential dorsoventral growth in the dorsal part of the body.

Three-dimensional Ultrasound in Detection of Fetal Anomalies

In the history of 3D/4D ultrasound technology, the great achievement was high definition (HD) live technology. This technology is a novel ultrasound technique that improves the 3D/4D images. HDlive ultrasound has resulted in remarkable progress in visualization of early embryos and fetuses and in the development of sonoembryology. HDlive uses an adjustable light source and software that calculates the propagation of light through surface structures in relation to the light direction. The virtual light source produces selective illumination, and the respective shadows are created by the structures where the light is reflected. This combination of light and shadows increases depth perception and produces remarkable images that are more natural than those obtained with classic three-dimensional (3D) ultrasound. The virtual light can be placed in the front, back, or lateral sides, where viewing is desired until the best image is achieved. A great advantage is that the soft can be applied to all images stored in the machine's memory. With HDlive ultrasound, both structural and functional developments can be assessed from early pregnancy more objectively and reliably and, indeed, the new technology has moved embryology from postmortem studies to the in vivo environment. Practically, in obstetrical ultrasound, HDlive could be used during all three trimesters of pregnancy.

How to cite this article

Pooh RK, Kurjak A. Three-dimensional Ultrasound in Detection of Fetal Anomalies. Donald School J Ultrasound Obstet Gynecol 2016;10(3):214-234.

Development of the human infrahepatic inferior caval and azygos venous systems

Differences in opinion regarding the development of the infrahepatic inferior caval and azygos venous systems in mammals centre on the contributions of 'caudal cardinal', 'subcardinal', 'supracardinal', 'medial and lateral sympathetic line' and 'sacrocardinal' veins. The disagreements appear to arise from the use of topographical position rather than developmental origin as criterion to define separate venous systems. We reinvestigated the issue in a closely spaced series of human embryos between 4 and 10 weeks of development. Structures were visualized with the Amira(®) reconstruction and Cinema4D(®) remodelling software. The vertebral level and neighbouring structures were used as topographic landmarks. The main results were that the caudal cardinal veins extended caudally from the common cardinal vein between CS11 and CS15, followed by the development of the subcardinal veins as a plexus sprouting ventrally from the caudal cardinal veins. The caudal cardinal veins adapted their course from lateral to medial relative to the laterally expanding lungs, adrenal glands, definitive kidneys, sympathetic trunk and umbilical arteries between CS15 and CS18, and then became interrupted in the part overlaying the regressing mesonephroi (Th12-L3). The caudal part of the left caudal cardinal vein then also regressed. The infrarenal part of the inferior caval vein originated from the right caudal cardinal vein, while the renal part originated from subcardinal veins. The azygos veins developed from the remaining cranial part of the caudal cardinal veins. Our data show that all parts of the inferior caval and azygos venous systems developed directly from the caudal cardinal veins or from a plexus sprouting from these veins.

A New Field of ‘Fetal Sono-ophthalmology’ by 3D HDlive Silhouette and Flow

Diagnostic ultrasound technology has remarkably evolved and contributed to accurate prenatal diagnosis and management. HDlive silhouette and HDlive flow are new applications of threedimensional (3D) ultrasound technology. The algorism of HDlive silhouette creates a gradient at organ boundaries where an abrupt change of the acoustic impedance exists within tissues. HDlive silhouette and flow can be called as ‘see-through fashion’. The advantages of this ‘see-through fashion’ imaging are comprehensive orientation and persuasive localization of inner structure as well as of fetal angiostructure inside the morphological structure. Picture of the month demonstrates the fetal eye at 19 weeks of gestation. The lens, vitreous body and hyaloid artery inside the vitreous humor are well demonstrated. The hyaloid artery is retrogressing during pregnancy and no remnant hyaloid artery is visible in most of mature neonates. Therefore, hyaloid artery can be observed in only young fetuses and immature neonates. HDlive silhouette and flow has enabled us to depict fetal eye and ocular vascularity three-dimensionally. This new technology has a great potential to open a new field of ‘fetal 3D sono-ophthalmology’, which has been never invented by conventional ultrasound technology.

How to cite this article

Pooh RK. A New Field of ‘Fetal Sonoophthalmology’ by 3D HDlive Silhouette and Flow. Donald School J Ultrasound Obstet Gynecol 2015;9(3):221-222.

MRI and ultrasound fusion imaging for prenatal diagnosis

OBJECTIVE

A combination of magnetic resonance imaging (MRI) images with real time high-resolution ultrasound known as fusion imaging may improve prenatal examination. This study was undertaken to evaluate the feasibility of using fusion of MRI and ultrasound (US) in prenatal imaging.

STUDY DESIGN

This study was conducted in a tertiary referral center. All patients referred for prenatal MRI were offered to undergo fusion of MRI and US examination. All cases underwent 1.5 Tesla MRI protocol including at least 3 T2-weighted planes. The Digital Imaging and Communications in Medicine volume dataset was then loaded into the US system for manual registration of the live US image and fusion imaging examination.

RESULTS

Over the study period, 24 patients underwent fusion imaging at a median gestational age of 31 (range, 24-35) weeks. Data registration, matching and then volume navigation was feasible in all cases. Fusion imaging allowed superimposing MRI and US images therefore providing with real time imaging capabilities and high tissue contrast. It also allowed adding a real time Doppler signal on MRI images. Significant fetal movement required repeat-registration in 15 (60%) cases. The average duration of the overall additional scan with fusion imaging was 10 ± 5 minutes.

CONCLUSION

The combination of fetal real time MRI and US image fusion and navigation is feasible. Multimodality fusion imaging may enable easier and more extensive prenatal diagnosis.

Morphology and morphometry of fetal liver at 16-26 weeks of gestation by magnetic resonance imaging: Comparison with embryonic liver at Carnegie stage 23

AIM

Normal liver growth was described morphologically and morphometrically using magnetic resonance imaging (MRI) data of human fetuses, and compared with embryonic liver to establish a normal reference chart for clinical use.

METHODS

MRI images from 21 fetuses at 16-26 weeks of gestation and eight embryos at Carnegie stage (CS)23 were investigated in the present study. Using the image data, the morphology of the liver as well as its adjacent organs was extracted and reconstructed three-dimensionally. Morphometry of fetal liver growth was performed using simple regression analysis.

RESULTS

The fundamental morphology was similar in all cases of the fetal livers examined. The liver tended to grow along the transversal axis. The four lobes were clearly recognizable in the fetal liver but not in the embryonic liver. The length of the liver along the three axes, liver volume and four lobes correlated with the bodyweight (BW). The morphogenesis of the fetal liver on the dorsal and caudal sides was affected by the growth of the abdominal organs, such as the stomach, duodenum and spleen, and retroperitoneal organs, such as the right adrenal gland and right kidney. The main blood vessels such as inferior vena cava, portal vein and umbilical vein made a groove on the surface of the liver. Morphology of the fetal liver was different from that of the embryonic liver at CS23.

CONCLUSION

The present data will be useful for evaluating the development of the fetal liver and the adjacent organs that affect its morphology.

Current Role of 3D/4D Sonography in Obstetrics and Gynecology

Modern 3D/4D sonography provides a routine method not only for storing single image planes as in 2D ultrasound but also for storing complete sets of volume data in the computer memory. Once acquisition is completed, all volumes can be accessed from the memory and normal and abnormal findings in both obstetrics and gynecology can be demonstrated in different display modes. Furthermore digital storage of volumes permits virtual examinations by reloading of volumes and navigating through them in the absence of the patient.

This review article would like to give an illustration of the latest technologies in 3D/4D ultrasound in obstetrics and gynecology.

How to cite this article

Merz E, Pashaj S. Current Role of 3D/ 4D Sonography in Obstetrics and Gynecology. Donald School J Ultrasound Obstet Gynecol 2013;7(4):400-408.

Neurosonoembryology by three-dimensional ultrasound

High-resolution three-dimensional (3D) ultrasound has enabled the visualization of small embryos and fetuses, and embryology in vivo - '3D sonoembryology' - has been established based on conventional embryology. Recently developed imaging techniques allow the definition of in-vivo anatomy including visualization of the embryonic circulation and dynamic features that could not be characterized in fixed specimens. Three-dimensional ultrasound has facilitated increasingly accurate and objective prenatal diagnoses of cranium bifidum/spina bifida, holoprosencephaly and associated anomalies in the first trimester and may allow detection of pathologic central nervous system (CNS) development at an earlier gestational age. It may be no exaggeration to suggest that prenatal diagnoses of fetal abnormalities have shifted from second to first trimester. However, fetal brain develops rapidly in the second trimester, therefore early scanning covers only selected CNS anomalies described in this article and serial continuous observation in the second trimester will be required.

Normal anatomy by three-dimensional ultrasound in the second and third trimesters

Fetal brain is rapidly developing and changing its appearance week by week during pregnancy. It is quite difficult to observe detailed structure of the brain by conventional transabdominal sonography. Transvaginal high-resolution ultrasound and three-dimensional (3D) ultrasound have been establishing sonoembryology in the first trimester as well as neurosonography. It is possible to observe the whole brain structure by magnetic resonance imaging in the latter half of pregnancy but transvaginal high-resolution 3D ultrasound is also a powerful modality for understanding brain anatomy. As for brain vascularization, main arteries and veins have been demonstrated and evaluated in various central nervous system conditions. Transvaginal high-resolution 3D ultrasound can demonstrate even cerebral fine vascular anatomy such as medullary vessels and it is greatly expected to estimate neurological prognosis in relation to vascular development during the fetal period.

Fetal surgery for myelomeningocele: progress and perspectives

Myelomeningocele (MMC), one of the most common congenital malformations, can result in severe lifelong disabilities, including paraplegia, hydrocephalus, Chiari II malformation, bowel and bladder dysfunction, skeletal deformations, and neurocognitive impairment. Experimental studies provide compelling evidence that the neurological deficits associated with MMC are not simply caused by incomplete neurulation but rather by the prolonged exposure of the vulnerable neural elements to the intrauterine environment. MMC is the first non-lethal anomaly considered for fetal surgical intervention, necessitating a careful analysis of risks and benefits. Retrospective and prospective randomized studies suggest that fetal surgery of MMC before 26 weeks of gestation may preserve neuromotor function, reverse hindbrain herniation, and reduce the need for ventriculoperitoneal shunting. However, these studies also demonstrate that fetal surgery is associated with significant maternal and fetal risks. Consequently, additional research is necessary to further elucidate the pathophysiology of MMC, to define the ideal timing and technique of fetal closure, and to evaluate the long-term implications of prenatal intervention.

Diagnosis of fetal limb abnormalities before 15 weeks: cause for concern

OBJECTIVES

The purposes of this study were (1) to identify cases of limb abnormalities identified before 15 weeks and correlate with outcomes and (2) to assess first-trimester nuchal translucency examinations to determine how frequently the upper and lower limbs were identified.

METHODS

A retrospective review was conducted of sonographic studies up to 15 weeks' gestational age from 2003 to 2010 at our high-risk fetal center. Data were collected regarding fetal gestational age, limb abnormalities, associated anatomic abnormalities, pregnancy outcomes, karyotypes, autopsy results, and the utility of transabdominal sonography, transvaginal sonography, and 3-dimensional sonography. A retrospective analysis of 100 consecutive first-trimester examinations was also conducted to assess the sensitivity of transabdominal sonography in visualization of limb buds.

RESULTS

A total of 15 cases were identified with a mean gestational age of 12 weeks 6 days. Club hand was the most common abnormality seen (8 cases), followed by absence of long bones (5 cases), a missing limb (5 cases), club foot (5 cases), shortening of long bones (2 cases), abnormal hands (2 cases), clenched hands (2 cases), and overlapping digits (1 case). Trisomy 18 was present in 9 cases. Transabdominal sonography allowed for detection of all limb buds in 100 consecutive nuchal translucency examinations and 9 of 15 cases of limb abnormalities. Four of the cases resulted in fetal death, and the remaining 11 cases were terminated.

CONCLUSIONS

Fetal limb abnormalities can be detected on sonography before 15 weeks' gestational age and are often associated with serious congenital conditions, especially trisomy 18. Transabdominal sonography alone can show most of these abnormalities, although transvaginal and 3-dimensional sonography can provide additional information. Targeted evaluation of fetal limbs during sonography before 15 weeks should be considered in high-risk populations.