Demonstration of cranial sutures and fontanelles at 15 to 16 weeks of gestation: a comparison between two-dimensional and three-dimensional ultrasonography

Prenatal diagnosis of microcephaly through combined MRI and ultrasonography: Analysis of a case series

INTRODUCTION

Intrauterine microcephaly is a complex and lifelong condition that poses significant ethical challenges for clinicians and parents. The prognosis of microcephaly is highly variable and depends on the underlying cause and severity. In addition, microcephaly is often associated with various comorbidities, including intellectual disability, developmental delay, and epilepsy. Ultrasonography (US) is currently the most commonly used imaging modality for detecting microcephaly in the second trimester of pregnancy. However, antenatal brain magnetic resonance imaging (MRI) is increasingly being used as a more sensitive tool to identify structural abnormalities that may suggest a specific diagnosis. In this study, we report a case series of microcephaly diagnosed through the combination of MRI and US.

PATIENT CONCERNS

How to utilize a combination of MRI and US to screen for fetal microcephaly.

DIAGNOSIS

Based on the results of US and MRI examinations, patient 1 was found to have other craniocerebral malformations, patient 2 demonstrated macrogyria, and patient 3 exhibited skull irregularities.

INTERVENTIONS

The pregnancies of all 3 patients were terminated through the induction of labor by injecting Rivanol into the amniotic cavity.

OUTCOMES

The 3 patients were discharged after a period of observation.

CONCLUSION

US is an important tool for diagnosing fetal microcephaly. However, MRI can overcome the limitations of US and detect additional brain structural abnormalities, thereby providing more specific and valuable prenatal diagnostic information. Therefore, combining MRI and US has significant diagnostic value for fetal microcephaly.

The Evolution of the Role of Imaging in the Diagnosis of Craniosynostosis: A Narrative Review

Craniosynostosis, the premature closure of cranial sutures, is one of the principal causes of pediatric skull deformities. It can cause aesthetic, neurological, acoustic, ophthalmological complications up to real emergencies. Craniosynostosis are primarily diagnosed with accurate physical examination, skull measurement and observation of the deformity, but the radiological support currently plays an increasingly important role in confirming a more precise diagnosis and better planning for therapeutic interventions. The clinician must know how to diagnose in the earliest and least invasive way for the child. In the past, technological limitations reduced the choices; today, however, there are plenty of choices and it is necessary to use the various types of available imaging correctly. In the future, imaging techniques will probably rewrite the common classifications we use today. We provide an updated review of the role of imaging in this condition, through the ages, to outline the correct choice for the clinician for an early and non-invasive diagnosis.

Craniosynostosis: Clinical Presentation, Genetics, and Prenatal Diagnosis

Importance

Craniosynostosis is a fetal condition caused by premature closure of the cranial sutures. Through provider awareness, we can raise suspicion in high-risk individuals, increase prenatal detection, optimize genetic testing, perform appropriate antenatal surveillance and delivery planning, and allow for a comprehensive, multidisciplinary approach to treatment.

Objective

The aim of this study was to review what is currently known regarding the genetics, pathophysiology, diagnosis, and treatment of craniosynostosis for the obstetric care provider.

Evidence Acquisition

A comprehensive literature review was performed using the PubMed database with the search term "craniosynostosis." The search was limited to the English language.

Results

A total of 220 articles were identified, and a total of 53 were used in completion of this article. The results highlight the multiple factors involved with abnormal suture formation, including various genetic factors. Although rare at this time, prenatal detection can allow families to prepare and practitioners to provide appropriate clinical treatment. Both 3-dimensional sonography and magnetic resonance imaging have been identified as modalities to aid in detection for high-risk individuals. Early referral allows for less-invasive surgical outcomes with lower complication rates.

Results

Familiarity with craniosynostosis among obstetric providers can improve patient counseling, prenatal detection rates, and appropriate antepartum, intrapartum, and postpartum counseling.

Role of 3-D ultrasound in clinical obstetric practice: evolution over 20 years

The use of 3-D ultrasound in obstetrics has undergone dramatic development over the past 20 years. Since the first publications on this application in clinical practice, several 3-D ultrasound techniques and rendering modes have been proposed and applied to the study of fetal brain, face and cardiac anatomy. In addition, 3-D ultrasound has improved calculations of the volume of fetal organs and limbs and estimations of fetal birth weight. And furthermore, angiographic patterns of fetal organs and the placenta have been assessed using 3-D power Doppler ultrasound quantification. In this review, we aim to summarize current evidence on the clinical relevance of these methodologies and their application in obstetric practice.

Surface area measurement using rendered three-dimensional ultrasound imaging: an in-vitro phantom study

OBJECTIVE

Cranial sutures and fontanelles can be reliably demonstrated using three-dimensional (3D) ultrasound with rendering. Our objective was to assess the repeatability and validity of fontanelle surface area measurement on rendered 3D images.

METHODS

This was an in-vitro phantom validation study. Four holes, representing fontanelles, were cut on a flat vinyl tile. The phantom was scanned in a test-tank by two sonographers, at four different depths and using two different 3D sweep directions. The surface areas were measured on scan images and also directly from the phantom for comparison. Coefficients of variation (CVs), intraclass correlation coefficients (ICCs) and Bland-Altman plots were used for repeatability analysis. Validity was expressed as the percentage difference of the measured area from the true surface area.

RESULTS

Validity of measurement was satisfactory with a mean percentage difference of - 5.9% (median = - 3.5%). The 95% limits of agreement were - 23.9 to 12.1%, suggesting that random error is introduced during image generation and measurement. Repeatability of caliper placement on the same image was higher (intraobserver CV = 1.6%, ICC = 0.999) than for measurement of a newly generated scan image (intraobserver CV = 5.5%, ICC = 0.992). Reduced accuracy was noted for the smallest shape tested.

CONCLUSION

Surface area measurements on rendered 3D ultrasound images are accurate and reproducible in vitro.

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'.

Metopic suture in fetuses with trisomy 21 at 11 + 0 to 13 + 6 weeks of gestation

OBJECTIVE

To investigate the development of the frontal bones and metopic suture in fetuses with trisomy 21 at 11 + 0 to 13 + 6 weeks of gestation.

METHODS

Three-dimensional (3D) ultrasound was used to measure the height of and gap between the frontal bones in 75 fetuses with trisomy 21 and these were compared to the measurements in 200 normal fetuses at 11 + 0 to 13 + 6 (median, 12 + 6) weeks of gestation.

RESULTS

In the fetuses with trisomy 21, compared to the normal fetuses, there was no significant difference in either the height of the frontal bones (mean difference 0.16 SD, range -1.78 to 2.17 SD; P = 0.369) or the gap between them (mean difference 0.012, 95% CI -0.073 to 0.097; P = 0.780). Additionally, within the group of trisomy 21 fetuses there were no significant differences in the development of the frontal bones and metopic suture between those with absent (n = 46) and those with present (n = 29) nasal bone.

CONCLUSIONS

In trisomy 21 the development of the frontal bones and metopic suture is as normal and is independent from the development of the nasal bones.

Metopic suture in fetuses with holoprosencephaly at 11 + 0 to 13 + 6 weeks of gestation

OBJECTIVE

To investigate the development of the metopic suture in fetuses with holoprosencephaly at 11 + 0 to 13 + 6 weeks of gestation.

METHODS

Three-dimensional (3D) ultrasound was used to measure the height and gap between the frontal bones in 200 normal fetuses and in nine fetuses with holoprosencephaly at 11 + 0 to 13 + 6 (median, 12) weeks of gestation.

RESULTS

In the 200 normal fetuses, the height of the frontal bones increased significantly with gestation from a mean of 2.5 mm (5(th) and 95(th) centiles: 1.9 mm and 3.3 mm) at 11 weeks to 6.1 mm (5(th) and 95(th) centiles: 4.6 mm and 8.1 mm) at 13 + 6 weeks. The gap between the two frontal bones did not change significantly with gestation (mean: 1.5 mm; 5(th) centile: 1.0 mm; 95(th) centile: 2.0 mm). In fetuses with holoprosencephaly, the height of the frontal bones was significantly larger (mean difference, 5.6 SDs; range, 3.9-7.7 SDs; P < 0.0001) and the gap was significantly smaller (mean 0.2 mm, range 0-0.8 mm; P < 0.0001) than those in normal fetuses.

CONCLUSIONS

Holoprosencephaly is associated with an accelerated development of the frontal bones and premature closure of the metopic suture.

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 sonographic description of abnormal metopic suture in second- and third-trimester fetuses

OBJECTIVE

To describe patterns of abnormal development of the metopic suture in association with fetal malformations during the second and third trimesters of pregnancy.

METHODS

This was a cross-sectional study of the frontal bones and metopic suture in 11 fetuses at 17-32 weeks of gestation. Cases were selected because there were obvious abnormalities in the metopic sutures. In each case, a malformation was detected by two-dimensional (2D) ultrasound and the abnormality of the metopic suture was detected and evaluated on three-dimensional (3D) ultrasound, using transparent maximum mode.

RESULTS

There were essentially four patterns of abnormality in the metopic suture: firstly, delayed development with a V- or Y-shaped open suture, which is found in normal fetuses at 12-16 weeks; secondly, a U-shaped open suture, presumably due to upward growth of the frontal bones with delayed closure; thirdly, premature closure of the suture, which is normally observed after 32 weeks; fourthly, the presence of additional bone between the frontal bones. Premature closure of the suture or additional bone between the frontal bones was observed in fetuses with holoprosencephaly and abnormalities of the corpus callosum, whereas the V-, Y- and U-shaped metopic sutures were observed in fetuses with facial defects involving the orbits, nasal bones, lip, palate and mandible, in the absence of holoprosencephaly and abnormal corpus callosum.

CONCLUSIONS

This preliminary study describes the pattern of possible abnormalities of the metopic suture and should stimulate further investigation to establish the prevalence and evolution of abnormal sutures as well as the incidence and pattern of other associated defects.

Three-dimensional sonographic description of the fetal frontal bones and metopic suture

OBJECTIVE

To describe the morphology of the frontal bones and metopic suture at 9-34 weeks of gestation using three-dimensional (3D) ultrasonography.

METHODS

This was a cross-sectional study of the frontal bones and metopic suture in 16 fetuses at 9-34 weeks of gestation. 3D ultrasonography was used to obtain volumes of the whole fetal skull in the mid-sagittal plane. The volumes were analyzed using the rendering mode and transparent maximum mode in order to achieve a clear view of the frontal bones and the metopic suture.

RESULTS

At 9 weeks, a small ossification center was visible in the middle of each supraorbital part of the frontal bones and by 11 weeks the frontal bones appeared as 'thick eyebrows'. In the second trimester there was progressive radial bone expansion and delineation of the metopic suture and in the third trimester there was closure of the metopic suture, starting from the glabella and moving upwards towards the anterior fontanelle.

CONCLUSIONS

This study provides 3D ultrasound images that illustrate the process of ossification of the frontal bones and the subsequent development of the metopic suture during prenatal life.