Fetal magnetic resonance imaging and three-dimensional ultrasound in clinical practice: Applications in prenatal diagnosis

"A Picture Paints a Thousand Words"-A Systematic Review of the Ethical Issues of Prenatal Ultrasound

Prenatal ultrasound is a non-invasive diagnostic examination. Despite the recognized diagnostic value, this technology raises complex ethical questions. The aim of this study is to provide a comprehensive analysis that coherently maps the ethical challenges raised by prenatal ultrasound examination, both 2D and 3D. We performed a systematic literature review. Six databases were systematically searched. The results highlight how concerns related to beneficence, informed consent, and autonomy are mainly related to routine use of prenatal ultrasound in the clinical context, while considerations linked to overmedicalization of pregnancy, discrimination, and fetal ontology were often reported in relation to the impact ultrasound is having on medicine and society. Ethical issues in the context of pre-abortion ultrasound, obstetric practices in low-income settings, and keepsake ultrasound imaging were also greatly discussed. Since prenatal ultrasound practices critically impact pregnant people's autonomy and their role within pregnancy, we conclude that information providing strategies should be developed to appropriately inform pregnant people about the nature, purpose, risks, and choices revolving around prenatal ultrasound. In addition, as it is becoming increasingly difficult to separate the social and clinical dimensions of prenatal ultrasound, future research should focus on examining if and how such dimensions should be reconciled.

Postnatal treatment and evolution patterns of giant fetal hepatic hemangioma: a case series of 29 patients

OBJECTIVES

To explore the clinical characteristics, postnatal treatment and prognosis of giant fetal hepatic hemangioma (GFHH).

METHOD

Retrospective analysis was performed on children with giant fetal hepatic hemangioma (maximum tumor diameter > 40 mm) diagnosed by prenatal ultrasound and MRI from December 2016 to December 2020. These patients were observed and treated at the Children's Hospital of Fudan University after birth. The clinical data were collected to analyze the clinical characteristics, treatment, and prognosis of GFHH using independent sample t tests or Fisher's exact tests.

RESULTS

Twenty-nine patients who were detected by routine ultrasound in the second and third trimester of pregnancy with giant fetal hepatic hemangiomas were included. The first prenatal ultrasound diagnosis of gestational age was 34.0 ± 4.3 weeks, ranging from 22 to 39 weeks. Of the patients, 28 had focal GFHHs and 1 had multifocal GFHHs. Surgery was performed, and the diagnosis was confirmed histopathologically in two patients. There were 8 cases with echocardiography-based evidence of pulmonary hypertension, 11 cases had a cardiothoracic ratio > 0.6, and 4 cases had hepatic arteriovenous fistula (AVF). The median follow-up time was 37 months (range: 14-70 months). During the follow-up, 12 patients received medical treatment with propranolol as the first-line therapy. The treatment group had a higher ratio of cardiothoracic ratio > 0.6 (P = 0.022) and lower albumin levels (P = 0.018). Four (14.8%) lesions showed postnatal growth before involuting. Complete response was observed in 13 (13/29) patients, and partial response was observed in 16 (16/29) patients.

CONCLUSIONS

Fetal giant hepatic hemangioma is mainly localized, and its clinical outcome conforms to RICH (rapidly involuting) and PICH (partially involuting), but some fetal giant hepatic hemangiomas will continue to grow after birth and then gradually decrease. For uncomplicated giant fetal hepatic hemangioma, postnatal follow-up is the main concern, while those with complications require aggressive medical treatment. Propranolol may have no effect on the volume change of GFHH.

Superinfected and Ruptured Occipital Meningocele: Case Report

Meningocele is a rare congenital malformation of the central nervous system resulting from a herniation of the meninges containing cerebrospinal fluid through a bony defect in the skull. It is part of neural tube closure anomalies. The overall incidence of meningocele is 0.8 to 3 per 10 000 live births; it varies based on geographical location and race, with a predominance of occipital localization. Among diagnostic methods, computed tomography (CT) and magnetic resonance imaging (MRI) remain crucial examinations. Prenatal diagnosis of this malformation primarily relies on ultrasound and screening through maternal serum alpha-fetoprotein (AFP) levels. They typically manifest very early at birth with a highly suggestive radioclinical presentation. Surgical treatment usually allows for a definitive cure. Superinfection and rupture of the meningocele are exceptional, resulting from delayed diagnosis and management. In several developed countries, prevention through genetic counseling and the intake of folic acid during the periconceptional period, along with accurate prenatal diagnosis and the legalization of therapeutic abortion, has led to a decrease in the prevalence of meningoceles. In less developed countries, where there is a delay in diagnosis in exceptional cases, superinfection and rupture may occur. We present the case of an 8-month-old infant with a complicated occipital meningocele with superinfection and rupture.

Association of deep phenotyping with diagnostic yield of prenatal exome sequencing for fetal brain abnormalities

PURPOSE

To evaluate whether deep prenatal phenotyping of fetal brain abnormalities (FBAs) increases diagnostic yield of trio-exome sequencing (ES) compared with standard phenotyping.

METHODS

Retrospective exploratory analysis of a multicenter prenatal ES study. Participants were eligible if an FBA was diagnosed and subsequently found to have a normal microarray. Deep phenotyping was defined as phenotype based on targeted ultrasound plus prenatal/postnatal magnetic resonance imaging, autopsy, and/or known phenotypes of other affected family members. Standard phenotyping was based on targeted ultrasound alone. FBAs were categorized by major brain findings on prenatal ultrasound. Cases with positive ES results were compared with those that have negative results by available phenotyping, as well as diagnosed FBAs.

RESULTS

A total of 76 trios with FBAs were identified, of which 25 (33%) cases had positive ES results and 51 (67%) had negative results. Individual modalities of deep phenotyping were not associated with diagnostic ES results. The most common FBAs identified were posterior fossa anomalies and midline defects. Neural tube defects were significantly associated with receipt of a negative ES result (0% vs 22%, P = .01).

CONCLUSION

Deep phenotyping was not associated with increased diagnostic yield of ES for FBA in this small cohort. Neural tube defects were associated with negative ES results.

Ultrasound and fetal magnetic resonance imaging: Clinical performance in the prenatal diagnosis of orofacial clefts and mandibular abnormalities

Cleft lip, with or without cleft palate, is the most common congenital craniofacial anomaly and the second most common birth defect worldwide. Micrognathia is a rare facial malformation characterized by small, underdeveloped mandible and frequently associated with retrognathia. Second- and third-trimester prenatal ultrasound is the standard modality for screening and identification of fetal orofacial abnormalities, with a detection rate in the low-risk population ranging from 0% to 73% for all types of cleft. The prenatal ultrasonography detection can also be performed during the first trimester of pregnancy. Given the potential limitations of obstetric ultrasound for examining the fetal face, such as suboptimal fetal position, shadowing from the surrounding bones, reduce amniotic fluid around the face, interposition of fetal limbs, umbilical cord and placenta, and maternal habitus/abdominal scars, the use of adjunct imaging modalities can enhance prenatal diagnosis of craniofacial anomalies in at-risk pregnancies. Fetal magnetic resonance imaging (MRI) is a potentially useful second-line investigation for the prenatal diagnosis of orofacial malformations with a pooled sensitivity of 97%. In this review, we discuss the role of ultrasound and fetal MRI in the prenatal assessment of abnormalities of the upper lip, palate, and mandible.

Fetal MRI prior to intrauterine surgery of open neural tube defects: What does the radiologist need to know

The management of myelomeningocele study trial showed significant prognostic improvement in fetal repair before 26 weeks of gestation. Hence, surgery in utero represents the best treatment option for open-neural tube defects (NTDs). Fetal surgery of open-NTDs has specific inclusion and exclusion criteria, which can be adequately studied with fetal MRI. The main concern: the spine (spinal defects other than Myelomeningocele and Myeloschisis, the level of the lesion higher than T1 or lower than S1 and the degree of kyphosis ≥ 30°), the skull/brain (no cerebellum herniation and Chiari II malformation and the presence of any intracranial abnormality unrelated to open NTDs), the uterus (cervix length less than 2 cm, multiple gestations and placental and uterine abnormalities) and any other fetal abnormality not attributed to spinal defect. In this review, we describe the fundamental role of fetal MRI in supporting therapeutic decisions in pre-surgery intrauterine planning through the accurate and comprehensive description of findings, providing a proposal of a structured report. In addition, we describe how post-surgical MRI is important in investigating the effectiveness of surgery and detecting repairing complications.

Advanced 3D Visualization and 3D Printing in Radiology

Since the discovery of X-rays in 1895, medical imaging systems have played a crucial role in medicine by permitting the visualization of internal structures and understanding the function of organ systems. Traditional imaging modalities including Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Ultrasound (US) present fixed two-dimensional (2D) images which are difficult to conceptualize complex anatomy. Advanced volumetric medical imaging allows for three-dimensional (3D) image post-processing and image segmentation to be performed, enabling the creation of 3D volume renderings and enhanced visualization of pertinent anatomic structures in 3D. Furthermore, 3D imaging is used to generate 3D printed models and extended reality (augmented reality and virtual reality) models. A 3D image translates medical imaging information into a visual story rendering complex data and abstract ideas into an easily understood and tangible concept. Clinicians use 3D models to comprehend complex anatomical structures and to plan and guide surgical interventions more precisely. This chapter will review the volumetric radiological techniques that are commonly utilized for advanced 3D visualization. It will also provide examples of 3D printing and extended reality technology applications in radiology and describe the positive impact of advanced radiological image visualization on patient care.

Normal fetal development of the cervical, thoracic, and lumbar spine: A postmortem study based on magnetic resonance imaging

OBJECTIVE

Before evaluating spinal pathology, it is essential to have knowledge of the normal spinal development at different gestational ages. This study aims to characterize normal spinal growth in human fetuses during the second and third trimesters.

METHODS

Postmortem 3.0 T magnetic resonance imaging (MRI) was performed on 55 fetuses at 17-42 gestational weeks by using three-dimensional T2-weighted sequences. Morphological changes and quantitative measurements of the fetal spine were assessed. The correlation between centrum ossification center volume (COCV) and gestational age was investigated.

RESULTS

The cervical, thoracic, and lumbar COCVs showed a positive relationship with gestational age (p < 0.05). No gender differences were found in the volumetric development of the cervical, thoracic, and lumbar centrum ossification centers (COCs). The average volumetric growth rate per COC was larger in the lumbar spine than in the cervical and thoracic spine. The L1-L5 COCVs also showed a linear positive relationship with gestational age.

CONSULTS

Postmortem 3.0 T MRI clearly demonstrated spinal changes in external contour and internal structure with gestational age. These findings expand our understanding of the early growth pattern of the human spine and could be further used to assess the developmental conditions of the fetal spine.

Case report and literature review: antenatal diagnosis of a fetal anaplastic astrocytoma

OBJECTIVES

To describe the ultrasonographic appearance of congenital anaplastic astrocytoma, so as to provide diagnostic clues for it. An updated review of the literature was also carried out.

RESULTS

There was a case of fetal anaplastic astrocytoma detected by ultrasound at 37 + 1 weeks of gestation. It showed that a hypoechoic mass was located in the left hemisphere with a relatively clear margin and subtle color flows. Prenatal magnetic resonance imaging (MRI) which was taken subsequently confirmed the result of ultrasound. Intratumoral hemorrhage was observed in later follow-up and further confirmed by histological examination. The fetus was delivered vaginally at 39 + 6 weeks. The infant died 2 h after delivery due to respiration failure. The histological examination confirmed an anaplastic astrocytoma.

CONCLUSIONS

Congenital anaplastic astrocytoma commonly detected by ultrasound has a relatively better perinatal prognosis, especially compared with glioblastoma. Prenatal ultrasonography diagnosis accurately is of critical importance. The anaplastic astrocytoma should be considered in cases in which fetal images reveal a heterogeneous echogenic mass in the brain, especially in the presence of intratumoral hemorrhage, subtle color flow, and relatively clear margin.

ACR Appropriateness Criteria® Second and Third Trimester Screening for Fetal Anomaly

The Appropriateness Criteria for the imaging screening of second and third trimester fetuses for anomalies are presented for fetuses that are low risk, high risk, have had soft markers detected on ultrasound, and have had major anomalies detected on ultrasound. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Interpeduncular angle: A new parameter for assessing intracranial hypotension in fetuses with spinal dysraphism

OBJECTIVE

To investigate the role of the interpeduncular angle (IPA) as a new indicator of intracranial hypotension in fetuses with open spinal dysraphism (SD).

METHODS

Two groups of fetuses undergoing magnetic resonance imaging (MRI) examination were identified. The study group included fetuses with open SD (n = 21), while the control group included fetuses with a normal brain and spine (n = 43). Two observers retrospectively evaluated axial T2-weighted images of the brain and the IPA was identified and measured. Other features of the Chiari II malformation were also evaluated in the study group and correlated with the IPA.

RESULTS

The average value (±SD) of the IPA for the study and control groups was 9.8° ± 18.5° and 60.2° ± 5.9°, respectively. The intergroup analysis of the IPA measurements revealed a statistically significant difference between the groups (p < 0.005). Brainstem slumping or cerebellar tonsillar descent, collapse of the fourth ventricle, and ventriculomegaly also had a significant correlation with a lower IPA (p = 0.001).

CONCLUSION

Measuring the IPA may be a useful technique for assessing the degree of intracranial hypotension in fetuses with open SD. This technique can also detect less severe cases of prenatal intracranial hypotension, even before cerebellar tonsillar descent. The lower IPA in fetuses with open SD further supports the theory that cerebrospinal fluid leakage, and not traction, is the underlying cause of Chiari II malformation.

Giant hepatic hemangioma in the fetus: case reports and updated review of the literature

OBJECTIVES

To describe three cases of giant fetal hepatic hemangioma detected by prenatal ultrasound in the third trimester of pregnancy and further confirmed by fetal magnetic resonance imaging (MRI). An updated review of the literature was also carried out.

RESULTS

In one case, there was an unexpected intrauterine demise at 35 weeks. The other two women delivered liveborn infants at term. The first of these two neonates had a stormy neonatal course and underwent endovascular embolization with limited clinical success. The infant presented multiple medical complications and was discharged home at five months of age. The second infant had an uneventful postnatal course. Subsequent follow-up scans showed progressive shrinkage of the lesion with no associated complications. A review of the English literature revealed a total of 42 cases prenatally diagnosed by ultrasound. The most relevant clinical and ultrasound findings are presented and the diverse perinatal outcomes related to this condition are discussed.

CONCLUSIONS

Fetal hepatic hemangiomas are exceedingly rare vascular tumors; however, they can be associated with several life-threatening conditions. They are usually detected by ultrasound, either incidentally or in the context of nonimmune hydrops secondary to high-output cardiac failure. Our review documents the increasing role of fetal MRI in the prenatal diagnosis and management of these cases. However, the improvement in prenatal diagnostic imaging techniques has not been associated with a better perinatal prognosis in the reported cases.

Normal development of the fetal spinal canal and spinal cord at T12 on 3.0-T MRI

BACKGROUND

The studies that described the dimensions of the normal fetal thoracic spinal canal and spinal cord on magnetic resonance imaging (MRI) are scarce.

PURPOSE

To determine the normal appearance of the fetal spinal canal and spinal cord at T12 across different gestational ages using 3.0-T MRI.

MATERIAL AND METHODS

The spines of 43 normal human fetuses, aged 15-40 weeks, were scanned by 3.0-T MRI. All specimens were scanned using a GE 3.0-T MRI scanner. Imaging of the T12 vertebrae was performed in the coronal, sagittal, and axial planes. The anterior-posterior (AP) diameter, width, and cross-sectional area of the spinal canal and spinal cord at T12 were measured. The influence of gestational age on these parameters was investigated with a scatter plot and linear regression analysis using Pearson correlation coefficient.

RESULTS

The normal morphology of the fetal vertebra at T12 can be clearly showed by MRI; the spinal canal appeared circular, while the spinal cord was ellipsoid. Linear regression analysis showed a significant positive correlation between the AP diameter, width, and cross-sectional area of the spinal canal at T12 and gestational age.

CONCLUSION

Postmortem MRI is a reliable method for understanding the growth dynamics of the spinal canal and spinal cord at T12. Findings from this study would benefit the prenatal diagnosis of congenital malformations by MRI.

Prenatal diagnosis of spina bifida: from intracranial translucency to intrauterine surgery

Accurate and timely prenatal diagnosis of spina bifida (SB) is a major goal of modern antenatal care. Prenatal screening for open SB should be first performed at the time of routine first-trimester ultrasound by examining the posterior fossa for obliteration or non-visualization of the fourth ventricle ("intracranial translucency") and cisterna magna. The second step of screening is the second-trimester anatomy scan, at which time the features of the Chiari type II malformation should be looked for, including ventriculomegaly, scalloping of the frontal bones ("lemon" sign), and backward and caudal displacement of the cerebellar vermis with obliteration of the cisterna magna ("banana" sign). In cases with positive findings, evaluation must include a focused examination of the spine for defects. In cases of closed SB and SB occulta, the cranial and posterior fossa features will not be present as they are not associated with leaking of spinal fluid and resultant hindbrain herniation, highlighting the fact that the spine should be examined thoroughly whenever possible during the second-trimester scan. In tertiary fetal medicine centers, two-dimensional and three-dimensional ultrasound allows an accurate determination of the location, type, extent, and upper level of the spinal defect as well as the presence of associated anomalies. Fetal magnetic resonance imaging should be restricted to candidates for intrauterine surgery as part of the preoperative protocol.

A brief history of topographical anatomy

This brief history of topographical anatomy begins with Egyptian medical papyri and the works known collectively as the Greco-Arabian canon, the time line then moves on to the excitement of discovery that characterised the Renaissance, the increasing regulatory and legislative frameworks introduced in the 18th and 19th centuries, and ends with a consideration of the impact of technology that epitomises the period from the late 19th century to the present day. This paper is based on a lecture I gave at the Winter Meeting of the Anatomical Society in Cambridge in December 2015, when I was awarded the Anatomical Society Medal.

Phenotip - a web-based instrument to help diagnosing fetal syndromes antenatally

Prenatal ultrasound can often reliably distinguish fetal anatomic anomalies, particularly in the hands of an experienced ultrasonographer. Given the large number of existing syndromes and the significant overlap in prenatal findings, antenatal differentiation for syndrome diagnosis is difficult. We constructed a hierarchic tree of 1140 sonographic markers and submarkers, organized per organ system. Subsequently, a database of prenatally diagnosable syndromes was built. An internet-based search engine was then designed to search the syndrome database based on a single or multiple sonographic markers. Future developments will include a database with magnetic resonance imaging findings as well as further refinements in the search engine to allow prioritization based on incidence of syndromes and markers.

Techniques, terminology, and indications for MRI in pregnancy

Fetal MRI is now a well-established imaging modality for the diagnostic evaluation of fetuses with congenital anomalies. In this article, the authors provide a brief overview of the physical principles involved in fetal MRI imaging, the sequences that are used in clinical practice today, current indications, and limitations. A review of current evidence supports the following indications for fetal MRI: suspected central nervous system anomalies, neck and oropharyngeal masses, diaphragmatic hernia, abdominal masses or bowel pathology not fully characterized by ultrasonography, and suspected fetal infection. Other indications should be decided on a case-by-case basis with close collaboration between the departments of maternal-fetal medicine and radiology. More research is needed to determine the role of fetal MRI in functional neuroimaging at higher magnetic field strengths (3T).