How accurately does current fetal imaging identify posterior fossa anomalies?

TSEN54 Gene-Related Pontocerebellar-Hypoplasia and Role of Prenatal MR Imaging: Besides the Common Posterior Fossa Cystic Malformations

Pontocerebellar-hypoplasia (PCH) related to TSEN54-gene mutation, a rare autosomal recessive disorder, can be associated with three different phenotypes: PCH2A, PCH4 and PCH5. Prenatal imaging features are very scant, in particular for PCH4 and PCH5. The aim of this letter is to illustrate key role of prenatal MR imaging in better evaluation of the cerebellar vermis-hemispheres and pons, which may lead to the differential diagnosis between three PCH TSEN54-related phenotypes already at mid-gestation based on the pattern of the degree of involvement of the vermis and the cerebellar cortex respectively.

Value of three-dimensional volume contrast imaging C combined with magnetic resonance imaging for diagnosis of fetal cerebellar vermis and posterior cranial fossa

OBJECTIVE

To assess the value of three-dimensional volume contrast imaging C (VCI-C) combined with magnetic resonance imaging (MRI) in the diagnosis of fetal posterior cranial cavity disease.

METHODS

This study retrospectively analyzed the imaging data of 100 pregnant women with diagnosed abnormal development of fetal cerebellar vermis or posterior cranial fossa in our hospital from January 2020 to February 2022. VCI-C combined with MRI was used to evaluate the morphology of fetal cerebellar vermis, and the display of primary fissures and secondary fissures. The angle between the brain stem and cerebellar vermis (BVA) and the angle between brain stem and cerebellar tentorium (BTA) were measured and compared through MRI images.

RESULTS

There was no significant difference between VCI-C and MRI in measuring the height, anteroposterior diameter, or area, BVA and BTA of fetal cerebellar vermis in the normal control group (P > 0.05). It can be considered that the two imaging methods are consistent in measuring the height, anteroposterior diameter and area, BVA, and BTA of the fetal cerebellar vermis in the normal control group. There was no significant difference between VCI-C and MRI in measuring the height, anterior posterior diameter and area, BVA, or BTA of the vermis in the group of fetal cerebellar vermis dysplasia (P > 0.05). The two imaging methods were comparable for all these measurements.

CONCLUSION

Combining three-dimensional VCI-Cwith MRI diagnosis, the median sagittal section of the cerebellar vermis can be observed, the morphologic structure of the vermis, and the anatomical structure of the posterior cranial fossa can be reflected stereoscopically. Quantitative indexes can be measured and calculated to evaluate the developmental abnormalities of the fetal cerebellar vermis and the lesions of the posterior cranial fossa. Their combined effect is better than that of a single application.

A myriad of posterior fossa cysts: A single center experience

Antenatal posterior fossa cystic lesions are intimidating due to overlapping imaging features of benign and severe malformations. Sonographic assessment of the posterior fossa with good resolution median sagittal and axial views, either primary or secondarily reconstructed, plays the lead role in antenatal evaluation, further enhanced when sequential assessments are added. We present 10 cases of fetal posterior fossa cystic lesions diagnosed in the first and second trimesters that were sequentially analyzed and followed up till delivery or termination. The ultrasound imaging appearance, evolution, and morphometry have been presented in this article.

Challenges in the pre- and post-natal diagnosis of posterior fossa cysts: A case report and review of historical evolution of descriptive terminologies

Background:

Radiological diagnoses of posterior fossa cystic abnormalities during antenatal and postnatal periods pose significant challenges as they may have similar early imaging features. Some of the frequently described entities are arachnoid cysts and Dandy-Walker malformations. Blake’s pouch cyst is relatively underdiagnosed. The main aim of the study was to explore these diagnostic challenges in the context of various descriptive terminologies and their prognostic implications.

Methods:

We illustrate this through our case, where fetal magnetic resonance imaging (MRI) at 36 weeks gestation showed small right cerebellum without hydrocephalus or hemorrhage. Possible differential diagnoses included Dandy-Walker malformation or posterior fossa malformations, facial hemangiomas, arterial anomalies, cardiac and eye anomalies, sternal clefting, and supraumbilical raphe.

Results:

Postnatal sonography noted posterior fossa cyst without hydrocephalus in a normal term infant, who went on to develop symptomatic hydrocephalus by 15 weeks. Computed tomography brain scan confirmed large subtentorial posterior fossa cyst and extensive internal hydrocephalus. Despite emergent ventriculoperitoneal shunt insertion, head circumference continued to rise. MRI scan showed persistent cyst. Subsequently, infant underwent endoscopic fenestration of the cyst with balloon septostomy and now has an age appropriate developmental profile.

Conclusion:

There is considerable discordance between antenatal and postnatal neuroimaging findings as highlighted in our case. Diagnostic conundrum here was whether this was an arachnoid or Blake’s pouch cyst. Differentiating between posterior fossa fluid collections is crucial for management, prognosis, and parental counseling. Close postnatal follow-up is essential to avert complications due to acute hydrocephalus.

In-depth characterization of neuroradiological findings in a large sample of individuals with autism spectrum disorder and controls

BACKGROUND

Autism spectrum disorder (ASD) is a group of neurodevelopmental conditions associated with quantitative differences in cortical and subcortical brain morphometry. Qualitative assessment of brain morphology provides complementary information on the possible underlying neurobiology. Studies of neuroradiological findings in ASD have rendered mixed results, and await robust replication in a sizable and independent sample.

METHODS

We systematically and comprehensively assessed neuroradiological findings in a large cohort of participants with ASD and age-matched controls (total N = 620, 348 ASD and 272 controls), including 70 participants with intellectual disability (47 ASD, 23 controls). We developed a comprehensive scoring system, augmented by standardized biometric measures.

RESULTS

There was a higher incidence of neuroradiological findings in individuals with ASD (89.4 %) compared to controls (83.8 %, p = .042). Certain findings were also more common in ASD, in particular opercular abnormalities (OR 1.9, 95 % CI 1.3-3.6) and mega cisterna magna (OR 2.4, 95 % CI 1.4-4.0) reached significance when using FDR, whereas increases in macrocephaly (OR 2.0, 95 % CI 1.2-3.2), cranial deformities (OR 2.4, 95 % CI: 1.0-5.8), calvarian / dural thickening (OR 1.5, 95 % CI 1.0-2.3), ventriculomegaly (OR 3.4, 95 % CI 1.3-9.2), and hypoplasia of the corpus callosum (OR 2.7, 95 % CI 1.1-6.3) did not survive this correction. Furthermore, neuroradiological findings were more likely to occur in isolation in controls, whereas they clustered more frequently in ASD. The incidence of neuroradiological findings was higher in individuals with mild intellectual disability (95.7 %), irrespective of ASD diagnosis.

CONCLUSION

There was a subtly higher prevalence of neuroradiological findings in ASD, which did not appear to be specific to the condition. Individual findings or clusters of findings may point towards the neurodevelopmental mechanisms involved in individual cases. As such, clinical MRI assessments may be useful to guide further etiopathological (genetic) investigations, and are potentially valuable to fundamental ASD research.

Taenia-tela choroidea complex and choroid plexus location help distinguish Dandy-Walker malformation and Blake pouch cysts

BACKGROUND

Dandy-Walker malformation and Blake pouch cysts can have overlapping imaging features. The choroid plexus and associated taenia-tela choroidea complex are displaced inferolaterally in Dandy-Walker malformation and below the vermis in Blake pouch cysts.

OBJECTIVE

To determine the normal fetal and postnatal MR appearance of the choroid plexus and taenia-tela choroidea complex, and whether their location can help distinguish Dandy-Walker malformation from Blake pouch cysts.

MATERIALS AND METHODS

In this retrospective study, we evaluated brain MR exams from normal-appearing fetuses (gestational age 19-38 weeks) and infants, fetal and postnatal exams in Blake pouch cysts and Dandy-Walker malformation, and ambiguous cases equivocal for mild Dandy-Walker malformation and Blake pouch cysts. We documented choroid plexus and the taenia-tela choroidea complex location and axial and sagittal angles in each case. Then we contrasted and compared the original and updated fetal diagnoses based on taenia-tela choroidea complex and choroid plexus positions.

RESULTS

The choroid plexus location and the taenia-tela choroidea complex location and angles varied significantly among normal exams, Blake pouch cyst exams and Dandy-Walker malformation exams (P<0.01). Dandy-Walker malformation showed inferolateral displacement of the taenia-tela choroidea complex and choroid plexus distant from the vermis. Adding the taenia-tela choroidea complex and choroid plexus into the assessment improved diagnostic accuracy, especially in ambiguous cases.

CONCLUSION

The location of the taenia-tela choroidea complex and choroid plexus provided additional diagnostic neuroimaging clues that could be used in conjunction with other conventional findings to distinguish Dandy-Walker malformation and Blake pouch cysts. Normal, Blake pouch cyst, and Dandy-Walker malformation cases differed with regard to taenia-tela choroidea complex and choroid plexus position. Inferolateral taenia-tela choroidea complex displacement distant from the vermian margin was characteristic of Dandy-Walker malformation.

Fetal MRI assessment of posterior fossa anomalies: A review

Prenatal ultrasound (US) is the first prenatal imaging tool for screening and evaluation of posterior fossa malformations since it is noninvasive, widely available, and safe for both mother and child. Fetal MRI is a widely used secondary technique to confirm, correct, or complement questionable US findings and plays an essential role in evaluating fetuses with suspected US findings and /or positive family history. The main sequences of fetal MRI consist of T2-weighted (T2w) ultrafast, single-shot sequences. Axial, coronal, and sagittal images are typically acquired allowing for a detailed evaluation of the posterior fossa contents. Also, various complimentary sequences, such as T1w, T2*w gradient sequences, or advanced techniques, including diffusion-weighted imaging, diffusion tensor imaging, and magnetic resonance spectroscopy, may provide additional information based on the studied malformation. Inclusion of these techniques should be done with careful risk-benefit analysis. The use of fetal MRI also aims to evaluate for associated anomalies. In addition, prenatal diagnosis of posterior fossa malformations is still a challenge but advances in knowledge in human developmental anatomy, genetic, and imaging recognition patterns have enabled us to shed some light on prognostic information that will help with the counseling of families. Finally, high-resolution late third trimester fetal MRI offers a safe alternative to early postnatal MR imaging, basically taking advantage of the uterine environment as a kind of "maternal incubator." Our goal is to discuss the spectrum of prenatal posterior fossa pathologies that can be studied by fetal MRI and their key neuroimaging features.

The Role of Fetal MRI for Suspected Anomalies of the Posterior Fossa

BACKGROUND

Posterior fossa anomalies can be diagnostic dilemmas during the fetal period. The prognosis for different diagnoses of the posterior fossa varies widely. We investigated whether fetal magnetic resonance imaging (MRI) and prenatal neurology consultation led to an alternate prognosis for fetuses referred due to concern for a fetal posterior fossa anomaly and concordance between pre- and postnatal diagnoses.

METHODS

This is a retrospective study of cases referred to the Prenatal Pediatrics Institute at Children's National Hospital from January 2012 to June 2018 due to concern for posterior fossa anomaly. Each encounter was scored for change in prognosis based upon clinical and fetal MRI report. Postnatal imaging was compared with prenatal imaging when available.

RESULTS

In total, 180 cases were referred for fetal posterior fossa anomalies based on outside obstetric ultrasound and had both fetal MRI and a neurology consultation. Fetal MRI and neurology consultation resulted in a change in fetal prognosis in 70% of cases. The most common referral diagnosis in our cohort was Dandy-Walker continuum, but it was not often confirmed by fetal MRI. In complex cases, posterior fossa diagnosis and prognosis determined by fetal MRI impacted choices regarding pregnancy management. Postnatal imaging was obtained in 57 (47%) live-born infants. Fetal and postnatal prognoses were similar in 60%.

CONCLUSIONS

Fetal diagnosis affects pregnancy management decisions. The fetal-postnatal imaging agreement of 60% highlights the conundrum of balancing the timing of fetal MRI to provide the most accurate diagnosis of the posterior fossa abnormalities in time to make pregnancy management decisions.

Brain fetal neuroradiology: a beginner's guide

The importance of fetal magnetic resonance imaging (MRI) in the prenatal diagnosis of central nervous system (CNS) anomalies is rapidly increasing. Fetal MRI represents a third level examination usually performed, as early as 18-20 weeks of gestational age, when a second level (expert) neuro-ultrasonography (US) evaluation raises the suspicion of a CNS anomaly or when a genetic disorder is known. Compared to the US, MRI has the advantage to allow a better visualization and characterization of brain structures so to detect anomalies not visible in the US, thus resulting in relevant implications for parent counselling and pregnancy management. Moreover, the improvement of MRI technologies permits to obtain ultrafast sequences, which minimize the drawback of movement artifacts, and to perform advanced studies. This review aims at providing a practical guide for trainees and fellows who are approaching fetal MRI. In the first part, we provide information about indications, safety and protocols based on the state-of-the-art sequences, with a mention on the innovations related to the use of a 3T scanner. The second part is focused on the normal development of the human fetal brain related to its MR appearance, whose knowledge is essential to detect possible abnormalities. The last section briefly describes the most frequent abnormalities in the fetal brain and spine as depicted by MRI.

Imaging spectrum of posterior fossa anomalies on foetal magnetic resonance imaging with an algorithmic approach to diagnosis

Posterior fossa abnormalities are one of the most common indications for performing foetal magnetic resonance imaging (FMRI). Ultrasonography is the initial imaging modality for assessment of foetal posterior fossa. Abnormal findings on ultrasonography warrant further evaluation with FMRI because it offers excellent soft-tissue contrast resolution and multiplanar capabilities. The neurological prognosis of different posterior fossa anomalies varies widely. FMRI plays a crucial role in confirming the diagnosis, assessing the prognosis, and counselling patients regarding continuation of pregnancy and possible post-natal developmental outcome. In this review we present the imaging spectrum of posterior fossa anomalies that readers can encounter in practice, highlight salient points in favour of each diagnosis, and provide a simplified algorithmic approach to reach the final diagnosis.

Biometric assessments of the posterior fossa by fetal MRI: A systematic review

BACKGROUND

Posterior fossa abnormalities (PFAs) are commonly identified within routine screening and are a frequent indication for fetal magnetic resonance imaging (MRI). Although biometric measurements of the posterior fossa (PF) are established on fetal ultrasound and MRI, qualitative visual assessments are predominantly used to differentiate PFAs.

OBJECTIVES

This systematic review aimed to assess 2-dimensional (2D) biometric measurements currently in use for assessing the PF on fetal MRI to delineate different PFAs.

METHODS

The protocol was registered (PROSPERO ID CRD42019142162). Eligible studies included T2-weighted MRI PF measurements in fetuses with and without PFAs, including measurements of the PF, or other brain areas relevant to PFAs.

RESULTS

59 studies were included - 6859 fetuses had 62 2D PF and related measurements. These included linear, area and angular measurements, representing measures of PF size, cerebellum/vermis, brainstem, and supratentorial measurements. 11 measurements were used in 10 or more studies and at least 1200 fetuses. These dimensions were used to characterise normal for gestational age, diagnose a range of pathologies, and predict outcome.

CONCLUSION

A selection of validated 2D biometric measurements of the PF on fetal MRI may be useful for identification of PFA in different clinical settings. Consistent use of these measures, both clinically and for research, is recommended.

Magnetic resonance imaging of the fetal central nervous system: Timing and consistency between pre- and postnatal diagnoses

INTRODUCTION

It has been shown that a proper comparison of prenatal ultrasound and magnetic resonance imaging (MRI) is possible only in the case of a short interval between tests. However, it is worth noting that the reference test is a postnatal examination. The aim of our study was to evaluate the effect of time between prenatal MRI (pMRI) and postnatal examinations on the consistency of diagnoses.

MATERIAL AND METHODS

The prospective observational study was carried out between 2014 and 2017 at the Department of Obstetrics and Perinatology of Krakow University Hospital. In total, 60 patients with fetuses suspected of central nervous system (CNS) defects were included in the study group. PMRI examinations were conducted in the third trimester of pregnancy.

RESULTS

The median gestational age of pMRI was 35 weeks and median of the time interval between carrying out pre- and postnatal test was 34.5 days. In the group of nonconcordant diagnoses, the interval was longer. The analysis did not show a statistically significant relationship between consistency of diagnoses and timing of pMRI. The median time of pregnancy at which pMRI was performed was similar in both groups. A prolongation of the interval between examinations reduced the probability of consistency of diagnoses.

CONCLUSIONS

The number of inaccurate results increased with the prolongation of the interval between pre- and postnatal tests.

KEY MESSAGE

Prolongation of the interval between pre- and postnatal increases number of inaccurate results.

Intrauterine versus post-mortem magnetic resonance in second trimester termination of pregnancy for central nervous system abnormalities

OBJECTIVE

To evaluate if limiting factors of intrauterine magnetic resonance imaging (iuMRI) performed in the early second trimester of pregnancy (19-23 weeks) affect its accuracy in comparison to post-mortem MRI (pmMRI) in fetuses that underwent termination of pregnancy (TOP) for central nervous system (CNS) defects.

STUDY DESIGN

This is a secondary analysis of a 10 years prospective observational study. Cases of TOP < 23 weeks for CNS malformation that had undergone neurosonography (NSG), iuMRI, pmMRI and autopsy were included. The agreement between iuMRI and pmMRI was calculated. The autopsy represented the gold-standard.

RESULTS

Overall, 143 TOPs for fetal congenital anomaly underwent the post-mortem diagnostic protocol. Of these, 31 cases underwent iuMRI and pmMRI for CNS abnormality. Three cases were excluded due to brain autolysis at autopsy. Corpus callosum defects were the most represented (16/28; 57 %). In only one case of posterior fossa defect, pmMRI identified the presence of vermian hypoplasia not diagnosed at iuMRI. In 2 cases (7%), iuMRI added clinically relevant additional findings to NSG, that were posteriorly confirmed by pmMRI.

CONCLUSIONS

The study shows that, at 19-23 weeks and for CNS defects, limiting factors that might influence the performance of iuMRI have little influence on iuMRI accuracy. This finding is particularly important for professionals who work in countries with legal bound for TOP in the early second trimester.

A survey of pediatric diagnostic radiologists in North America: current practices in fetal magnetic resonance imaging

BACKGROUND

Fetal magnetic resonance imaging (MRI) is an imaging examination in evolution. Rapid developments over recent decades have led to better image quality, an increased number of examinations and greater impact on patient care.

OBJECTIVE

To gather data regarding current practices among established programs in North America and provide information to radiologists interested in implementing or growing a fetal MRI service.

MATERIALS AND METHODS

An electronic survey containing 15 questions relevant to the use of fetal MRI was submitted to pediatric radiologists and neuroradiologists. Items regarded scheduling and reporting logistics, magnet strength, patient positioning and patient preparation. Answers and comments were collected, and descriptive statistics were summarized.

RESULTS

One hundred and six survey responses were evaluated. Of the survey responses, 62/106 (58.5%) allow fetal MR scheduling any time during the day and 72/105 (68.6%) exclusively use 1.5-T strength platforms for fetal MRI, while only 7/105 (6.7%) use exclusively 3 T. Patient positioning is variable: supine, 40/106 (37.8%); left lateral decubitus, 22/106 (20.8%), and, patient's choice, 43/106 (40.6%). Of the centers responding, 51/104 (49.0%) require no particular fasting instructions, while 20/104 (19.2%) request the patient avoid caffeine before the scanning.

CONCLUSION

Logistical trends in performing fetal MRI may supplement the American College of Radiology's published technical standards and offer guidance to radiologists new to the field.

Establishment of normative values for the fetal posterior fossa by magnetic resonance imaging

OBJECTIVE

Suspected Dandy-Walker continuum anomalies constitute a significant percentage of prenatal cases evaluated by magnetic resonance imaging (MRI). To unify the description of posterior fossa malformations, we sought to establish objective measurements for the posterior fossa in normal fetuses between 18 and 37 weeks gestation.

METHODS

T2-weighted images of normal fetal brains in sagittal projection were obtained from fetal magnetic resonance (MR) studies of normal brains performed from 2009 to 2017.121 fetal brains were included in the analysis. Three radiologists reviewed images and recorded the following for each case: superior posterior fossa angle (SPFA), posterior fossa perimeter, and tegmento-vermian angle (TVA).

RESULTS

For each feature, the mean of the measurements, the percentage of absolute difference of the reader measurement compared with mean measurement, and the interclass correlation (ICC) were calculated. Values are reported as mean ± standard deviation. Perimeter increases linearly with age, whereas the SPFA and the TVA are independent of gestational age. For all included cases, the SPFA averaged 100.9° ± 8° and the TVA averaged 2.5° ± 2.3°.

CONCLUSION

The superior posterior fossa angle, a novel measurement, and the posterior fossa perimeter can be used for establishing the expected size of the posterior fossa in second- and third-trimester fetuses by MRI.

Measurement of normal fetal cerebellar vermis at 24-32 weeks of gestation by transabdominal ultrasound and magnetic resonance imaging: A prospective comparative study

OBJECTIVES

Fetal cerebellar vermis may be assessed by ultrasound (US) or magnetic resonance imaging (MRI), and median-plane views are best for evaluation. The purpose of this study was to compare measurements of normal fetal vermis at 24-32 weeks of gestation obtained in median plane by transabdominal 2D-US, 3D-US, and MRI.

METHODS

A prospective study was conducted, examining normal singleton fetuses between 24 and 32 weeks of gestation. Within a 24-h period, median-plane views of posterior fossa were generated using 2D-US, 3D-US, and MRI. Measurements of anteroposterior (AP) diameter, craniocaudal (CC) diameter, mid-sagittal surface area, brainstem-vermis (BV) angle and brainstem-tentorium (BT) angle were obtained to compare these imaging modalities.

RESULTS

A total of 180 fetuses were studied. Correlation among imaging methods was good, marked by the following intraclass correlation coefficients: AP diameter, 0.955; CC diameter, 0.956; mid-sagittal surface area, 0.982; BV angle, 0.810; and BT angle, 0.865 (p < 0.001).

CONCLUSIONS

Visualization rates of MRI, 3D-US, and transabdominal 2D-US were decremental, MRI being superior in this regard. However, these three imaging modalities correlated well in measuring cerebellar vermis and its surroundings.

Pontine Tegmental Cap Dysplasia and Challenges in Facial Reconstructive Surgery

Pontine tegmental cap dysplasia (PTCD) is a rare condition that affects the brain stem and multiple cranial nerves, which can result in bilateral facial palsies, hearing loss, bilateral trigeminal nerve dysfunction, oculomotor apraxia, feeding difficulties, seizures, hypotonia, and undeveloped speech. We document a case in which a patient with PTCD presents with a challenging lip deformity and requires multidisciplinary treatment to improve reconstructive surgical success and treatment outcomes. An extensive literature review was conducted. This report serves to increase awareness of PTCD and the need for multidisciplinary teams to participate in reconstruction of facial defects in a complex medical setting.

Fetal cerebellar disorders

The embryologic development of the cerebellum extends over a long time period, thus making it vulnerable to a broad spectrum of malformations and disruptions. Knowledge of the main steps of fetal posterior fossa development; the normal imaging patterns at different stages of embryogenesis; the large spectrum of cerebellar malformations; and their clinical presentations enables diagnosis and precise counseling of parents. Sonography is the most important imaging method for the screening of cerebellar malformations since it is noninvasive, widely available, and safe for both mother and child. The ultrasonographic approach for the evaluation of the fetal posterior fossa is based on the classic transabdominal visualization of axial planes with addition when indicated of a more comprehensive, multiplanar transvaginal or transfundal approach, including coronal and sagittal imaging planes. Fetal magnetic resonance imaging (MRI) has become an adjunct to prenatal ultrasound since the 1980s. Good-quality images have been obtained thanks to the implementation of fast and ultrafast MRI sequences. Fetal MRI has higher-contrast resolution than prenatal sonography and may contribute to the differentiation of normal from abnormal tissue. Both prenatal neurosonography and fetal MRI enable accurate prenatal diagnosis of most posterior fossa anomalies.

Breaking bad news in prenatal medicine: a literature review

BACKGROUND

The diagnosis of a fetal anomaly in perinatal medicine forces expectant parents and healthcare providers to face the difficult process of breaking bad news.

OBJECTIVES

This exploratory literature review was aimed at providing a medical and psychological view of the psychological experience in expectant parents and physicians in the context of prenatal diagnosis of a fetal anomaly.

METHOD

An exploratory search of PubMed and PsycINFO/PsycARTICLES databases performed by an interdisciplinary team composed of a physician and psychologists. Search terms were: prenatal diagnosis AND bad news; prenatal diagnosis AND psychological consequences; prenatal diagnosis AND psychological sequelae; prenatal diagnosis AND fetal abnormality. The processing of selected articles followed a standardised five-step procedure.

RESULTS

A total of 860 articles were screened of which 32 were retained for analysis. Four main themes emerged from the explanatory content analysis: (1) parents' subjective experience; (2) physicians' subjective experience; (3) encounters between expectant parents and professionals; and (4) ethical challenges in breaking bad news in prenatal medicine.

CONCLUSION

Expectant parents go through a complex and multidimensional experience when the diagnosis of a fetal anomaly is disclosed. Simultaneously, physicians consider breaking bad news as a very stressful event and are poorly prepared in this regard. A better knowledge of factors underlying psychological adjustment of the parental dyad and on the subjective experience of physicians delivering these diagnoses could enable better adaptation for both patients and professionals.

Diagnostic accuracy of ultrasonography and magnetic resonance imaging for the detection of fetal anomalies: a blinded case-control study

OBJECTIVES

To compare the accuracy of two-dimensional ultrasound (2D-US), three-dimensional ultrasound (3D-US) and magnetic resonance imaging (MRI) for the diagnosis of congenital anomalies without prior knowledge of indications and previous imaging findings.

METHODS

This was a prospective, blinded case-control study comprising women with a singleton pregnancy with fetal congenital abnormalities identified on clinical ultrasound and those with an uncomplicated pregnancy. All women volunteered to undergo 2D-US, 3D-US and MRI, which were performed at one institution. Different examiners at a collaborating institution performed image interpretation. Sensitivity and specificity of the three imaging methods were calculated for individual anomalies, based on postnatal imaging and/or autopsy as the definitive diagnosis. Diagnostic confidence was graded on a four-point Likert scale.

RESULTS

A total of 157 singleton pregnancies were enrolled, however nine cases were excluded owing to incomplete outcome, resulting in 148 fetuses (58 cases and 90 controls) included in the final analysis. Among cases, 13 (22.4%) had central nervous system (CNS) anomalies, 40 (69.0%) had non-CNS anomalies and five (8.6%) had both CNS and non-CNS anomalies. The main findings were: (1) MRI was more sensitive than 3D-US for diagnosing CNS anomalies (MRI, 88.9% (16/18) vs 3D-US, 66.7% (12/18) vs 2D-US, 72.2% (13/18); McNemar's test for MRI vs 3D-US: P = 0.046); (2) MRI provided additional information affecting prognosis and/or counseling in 22.2% (4/18) of fetuses with CNS anomalies; (3) 2D-US, 3D-US and MRI had similar sensitivity for diagnosing non-CNS anomalies; (4) specificity for all anomalies was highest for 3D-US (MRI, 85.6% (77/90) vs 3D-US, 94.4% (85/90) vs 2D-US, 92.2% (83/90); McNemar's test for MRI vs 3D-US: P = 0.03); and (5) the confidence of MRI for ruling out certain CNS abnormalities (usually questionable for cortical dysplasias or hemorrhage) that were not confirmed after delivery was lower than it was for 2D-US and 3D-US.

CONCLUSIONS

MRI was more sensitive than ultrasonography and provided additional information that changed prognosis, counseling or management in 22.2% of fetuses with CNS anomalies. False-positive diagnoses for subtle CNS findings were higher with MRI than with ultrasonography. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Systematic review and meta-analysis of isolated posterior fossa malformations on prenatal imaging (part 2): neurodevelopmental outcome

OBJECTIVES

Diagnosis of isolated posterior fossa anomalies in children is biased by the fact that only those that are symptomatic are brought to the attention of the appropriate clinical personnel, and the reported rate is often affected by the adoption of different nomenclature, diagnostic criteria, outcome measures, duration of follow-up and neurodevelopmental tools. The aim of this systematic review was to explore the neurodevelopmental outcome of fetuses with a prenatal diagnosis of isolated posterior fossa anomalies.

METHODS

MEDLINE and EMBASE were searched electronically, utilizing combinations of the relevant medical subject heading terms for 'posterior fossa' and 'outcome'. Studies assessing the neurodevelopmental outcome in children with a prenatal diagnosis of isolated posterior fossa malformations were considered eligible. The posterior fossa anomalies analyzed included Dandy-Walker malformation (DWM), mega cisterna magna (MCM), Blake's pouch cyst (BPC) and vermian hypoplasia (VH). Two authors reviewed all abstracts independently. Quality assessment of the included studies was performed using the Newcastle-Ottawa Scale for cohort studies. Meta-analyses of proportions were used to combine data, and between-study heterogeneity was explored using the I(2) statistic.

RESULTS

A total of 1640 articles were identified; 95 were assessed for eligibility and a total of 16 studies were included in the systematic review. The overall rate of abnormal neurodevelopmental outcome in children with a prenatal diagnosis of DWM was 58.2% (95% CI, 21.8-90.0%) and varied from 0-100%. In those with a prenatal diagnosis of MCM, the rate of abnormal neurodevelopmental outcome was 13.8% (95% CI, 7.3-21.9%), with a range of 0-50%. There was no significant association between BPC and the occurrence of abnormal neurodevelopmental delay, with a rate of 4.7% (95% CI, 0.7-12.1%) and range of 0-5%. Although affected by the very small number of studies, there was a non-significant occurrence of abnormal neurodevelopmental delay in children with a prenatal diagnosis of VH, with a rate of 30.7% (95% CI, 0.6-79.1%) and range of 0-100%.

CONCLUSIONS

Fetuses diagnosed with isolated DWM are at high risk of abnormal neurodevelopmental outcome, while isolated MCM or BPC have a generally favorable outcome. The risk of abnormal developmental delay in cases with isolated VH needs to be further assessed. In view of the wide heterogeneity in study design, time of follow-up, neurodevelopmental tests used and the very small number of included cases, further future large prospective studies with standardized and objective protocols for diagnosis and follow-up are needed in order to ascertain the rate of abnormal neurodevelopmental outcome in children with isolated posterior fossa anomalies. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Systematic review and meta-analysis of isolated posterior fossa malformations on prenatal ultrasound imaging (part 1): nomenclature, diagnostic accuracy and associated anomalies

OBJECTIVE

To explore the outcome in fetuses with prenatal diagnosis of posterior fossa anomalies apparently isolated on ultrasound imaging.

METHODS

MEDLINE and EMBASE were searched electronically utilizing combinations of relevant medical subject headings for 'posterior fossa' and 'outcome'. The posterior fossa anomalies analyzed were Dandy-Walker malformation (DWM), mega cisterna magna (MCM), Blake's pouch cyst (BPC) and vermian hypoplasia (VH). The outcomes observed were rate of chromosomal abnormalities, additional anomalies detected at prenatal magnetic resonance imaging (MRI), additional anomalies detected at postnatal imaging and concordance between prenatal and postnatal diagnoses. Only isolated cases of posterior fossa anomalies - defined as having no cerebral or extracerebral additional anomalies detected on ultrasound examination - were included in the analysis. Quality assessment of the included studies was performed using the Newcastle-Ottawa Scale for cohort studies. We used meta-analyses of proportions to combine data and fixed- or random-effects models according to the heterogeneity of the results.

RESULTS

Twenty-two studies including 531 fetuses with posterior fossa anomalies were included in this systematic review. The prevalence of chromosomal abnormalities in fetuses with isolated DWM was 16.3% (95% CI, 8.7-25.7%). The prevalence of additional central nervous system (CNS) abnormalities that were missed at ultrasound examination and detected only at prenatal MRI was 13.7% (95% CI, 0.2-42.6%), and the prevalence of additional CNS anomalies that were missed at prenatal imaging and detected only after birth was 18.2% (95% CI, 6.2-34.6%). Prenatal diagnosis was not confirmed after birth in 28.2% (95% CI, 8.5-53.9%) of cases. MCM was not significantly associated with additional anomalies detected at prenatal MRI or detected after birth. Prenatal diagnosis was not confirmed postnatally in 7.1% (95% CI, 2.3-14.5%) of cases. The rate of chromosomal anomalies in fetuses with isolated BPC was 5.2% (95% CI, 0.9-12.7%) and there was no associated CNS anomaly detected at prenatal MRI or only after birth. Prenatal diagnosis of BPC was not confirmed after birth in 9.8% (95% CI, 2.9-20.1%) of cases. The rate of chromosomal anomalies in fetuses with isolated VH was 6.5% (95% CI, 0.8-17.1%) and there were no additional anomalies detected at prenatal MRI (0% (95% CI, 0.0-45.9%)). The proportions of cerebral anomalies detected only after birth was 14.2% (95% CI, 2.9-31.9%). Prenatal diagnosis was not confirmed after birth in 32.4% (95% CI, 18.3-48.4%) of cases.

CONCLUSIONS

DWM apparently isolated on ultrasound imaging is a condition with a high risk for chromosomal and associated structural anomalies. Isolated MCM and BPC have a low risk for aneuploidy or associated structural anomalies. The small number of cases with isolated VH prevents robust conclusions regarding their management from being drawn. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Diagnostic Value of Prenatal MR Imaging in the Detection of Brain Malformations in Fetuses before the 26th Week of Gestational Age

BACKGROUND AND PURPOSE

In several countries, laws and regulations allow abortion for medical reasons within 24-25 weeks of gestational age. We investigated the diagnostic value of prenatal MR imaging for brain malformations within 25 weeks of gestational age.

MATERIALS AND METHODS

We retrospectively included fetuses within 25 weeks of gestational age who had undergone both prenatal and postnatal MR imaging of the brain between 2002 and 2014. Two senior pediatric neuroradiologists evaluated prenatal MR imaging examinations blinded to postnatal MR imaging findings. With postnatal MR imaging used as the reference standard, we calculated the sensitivity, specificity, positive predictive value, and negative predictive value of the prenatal MR imaging in detecting brain malformations.

RESULTS

One-hundred nine fetuses (median gestational age at prenatal MR imaging: 22 weeks; range, 21-25 weeks) were included in this study. According to the reference standard, 111 malformations were detected. Prenatal MR imaging failed to detect correctly 11 of the 111 malformations: 3 midline malformations, 5 disorders of cortical development, 2 posterior fossa anomalies, and 1 vascular malformation. Prenatal MR imaging misdiagnosed 3 findings as pathologic in the posterior fossa.

CONCLUSIONS

The diagnostic value of prenatal MR imaging between 21 and 25 weeks' gestational age is very high, with limitations of sensitivity regarding the detection of disorders of cortical development.

Consensus paper: radiological biomarkers of cerebellar diseases

Hereditary and sporadic cerebellar ataxias represent a vast and still growing group of diseases whose diagnosis and differentiation cannot only rely on clinical evaluation. Brain imaging including magnetic resonance (MR) and nuclear medicine techniques allows for characterization of structural and functional abnormalities underlying symptomatic ataxias. These methods thus constitute a potential source of radiological biomarkers, which could be used to identify these diseases and differentiate subgroups of them, and to assess their severity and their evolution. Such biomarkers mainly comprise qualitative and quantitative data obtained from MR including proton spectroscopy, diffusion imaging, tractography, voxel-based morphometry, functional imaging during task execution or in a resting state, and from SPETC and PET with several radiotracers. In the current article, we aim to illustrate briefly some applications of these neuroimaging tools to evaluation of cerebellar disorders such as inherited cerebellar ataxia, fetal developmental malformations, and immune-mediated cerebellar diseases and of neurodegenerative or early-developing diseases, such as dementia and autism in which cerebellar involvement is an emerging feature. Although these radiological biomarkers appear promising and helpful to better understand ataxia-related anatomical and physiological impairments, to date, very few of them have turned out to be specific for a given ataxia with atrophy of the cerebellar system being the main and the most usual alteration being observed. Consequently, much remains to be done to establish sensitivity, specificity, and reproducibility of available MR and nuclear medicine features as diagnostic, progression and surrogate biomarkers in clinical routine.

Ultrasound diagnosis of bilateral cataracts in a fetus with possible cerebro-ocular congential muscular dystrophy during the routine second trimester anomaly scan

The finding of bilateral congenital cataracts in the fetus is rare. We report bilateral congenital cataracts detected during the routine second trimester anomaly scan, which subsequently were found to be associated with other congenital anomalies and the parents opted for a termination of pregnancy. At post-mortem, Muscle-Eye Brain disease or Walker-Warburg Syndrome was considered likely, which are autosomal recessive congenital muscular dystrophy disorders associated with cerebral, cerebellar, muscle and eye anomalies. On ultrasound, bilateral cataracts appear as echogenic, solid areas within the fetal orbits. The examination of the fetal face and orbits plays an important role in confirming fetal well-being antenatally. We propose that it should become a routine part of the structural survey of fetal anatomy during the obstetric anomaly scan. This is especially important in pregnancies previously affected by fetal cataracts or pregnancies at risk of rare genetic syndromes.

Normal fetal posterior fossa in MR imaging: new biometric data and possible clinical significance

BACKGROUND AND PURPOSE

Posterior fossa malformations are a common finding in prenatal diagnosis. The objectives of this study are to re-evaluate existing normal MR imaging biometric data of the fetal posterior fossa, suggest and evaluate new parameters, and demonstrate the possible clinical applications of these data.

MATERIALS AND METHODS

This was a retrospective review of 215 fetal MR imaging examinations with normal findings and 5 examinations of fetuses with a suspected pathologic posterior fossa. Six previously reported parameters and 8 new parameters were measured. Three new parameter ratios were calculated. Interobserver agreement was calculated by using the intraclass correlation coefficient.

RESULTS

For measuring each structure, 151-211 MR imaging examinations were selected, resulting in a normal biometry curve according to gestational age for each parameter. Analysis of the ratio parameters showed that vermian lobe ratio and cerebellar hemisphere ratio remain constant with gestational age and that the vermis-to-cisterna magna ratio varies with gestational age. Measurements of the 5 pathologic fetuses are presented on the normal curves. Interobserver agreement was excellent, with the intraclass correlation coefficients of most parameters above 0.9 and only 2 parameters below 0.8.

CONCLUSIONS

The biometry curves derived from new and existing biometric data and presented in this study may expand and deepen the biometry we use today, while keeping it simple and repeatable. By applying these extensive biometric data on suspected abnormal cases, diagnoses may be confirmed, better classified, or completely altered.

Fetal MRI: A Technical Update with Educational Aspirations

Fetal magnetic resonance imaging (MRI) examinations have become well-established procedures at many institutions and can serve as useful adjuncts to ultrasound (US) exams when diagnostic doubts remain after US. Due to fetal motion, however, fetal MRI exams are challenging and require the MR scanner to be used in a somewhat different mode than that employed for more routine clinical studies. Herein we review the techniques most commonly used, and those that are available, for fetal MRI with an emphasis on the physics of the techniques and how to deploy them to improve success rates for fetal MRI exams. By far the most common technique employed is single-shot T2-weighted imaging due to its excellent tissue contrast and relative immunity to fetal motion. Despite the significant challenges involved, however, many of the other techniques commonly employed in conventional neuro- and body MRI such as T1 and T2*-weighted imaging, diffusion and perfusion weighted imaging, as well as spectroscopic methods remain of interest for fetal MR applications. An effort to understand the strengths and limitations of these basic methods within the context of fetal MRI is made in order to optimize their use and facilitate implementation of technical improvements for the further development of fetal MR imaging, both in acquisition and post-processing strategies.

Fetal posterior fossa dimensions: normal and anomalous development assessed in mid-sagittal cranial plane by three-dimensional multiplanar sonography

OBJECTIVES

To construct nomograms of the dimensions of the fetal posterior fossa (PF), assessed in the mid-sagittal plane in the second and third trimesters, and to assess how measurements from fetuses with PF abnormalities deviate from our normal ranges.

METHODS

This was a prospective cross-sectional study of 378 healthy fetuses in low-risk singleton pregnancies between 15 and 35 weeks. PF size was evaluated in the mid-sagittal plane of the fetal head using three-dimensional multiplanar reconstruction (3D-MPR). The borders of the PF were defined from the clivus to the tentorium (clivotentorial distance, CTD) and from the occipital bone to the level of the upper mesencephalic edge (tecto-occipital distance, TOD), and the posterior fossa area (PFA) and perimeter (PFP) were assessed. Growth charts were produced. Thirty-nine fetuses diagnosed with PF malformations were analyzed by calculating the z-scores of PFA, PFP, TOD and CTD, relative to the developed nomograms.

RESULTS

Of the 378 healthy fetuses initially included, there were 281 with adequate visualization of the PF borders; i.e. PF mid-sagittal plane morphometry was feasible in 74.3% of cases. There was a linear relationship between each of PFA, PFP, TOD and CTD, and gestational age, with Pearson correlation coefficients of 0.97, 0.97, 0.96 and 0.95, respectively (P < 0.001 for each). Chiari II malformation (CM-II) and Dandy-Walker malformation (DWM) were associated with the greatest difference in PF size compared with normal; PFA z-scores exceeded 2.6 in all five DWM cases and were below -2.66 in all 11 CM-II cases.

CONCLUSIONS

Sonographic evaluation of fetal PF size in the mid-sagittal plane is feasible. Our constructed nomograms provide reference data that may be helpful when evaluating PF congenital malformations.

Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

OBJECTIVE

To evaluate the accuracy of fetal imaging in differentiating between diagnoses involving posterior fossa fluid collections and to investigate the postnatal outcome of affected infants.

METHODS

This was a retrospective study of fetuses with posterior fossa fluid collections, carried out between 2001 and 2010 in two referral centers for prenatal diagnosis. All fetuses underwent multiplanar neurosonography. Parents were also offered fetal magnetic resonance imaging (MRI) and karyotyping. Prenatal diagnosis was compared with autopsy or postnatal MRI findings and detailed follow-up was attempted by consultation of medical records and interview with parents and pediatricians.

RESULTS

During the study period, 105 fetuses were examined, at a mean gestational age of 24 (range, 17-28) weeks. Sonographic diagnoses (Blake's pouch cyst, n = 32; megacisterna magna, n = 27; Dandy-Walker malformation, n = 26; vermian hypoplasia, n = 17; cerebellar hypoplasia, n = 2; arachnoid cyst, n = 1) were accurate in 88% of the 65 cases in which confirmation was possible. MRI proved more informative than ultrasound in only 1/51 cases. Anatomic anomalies and/or chromosomal aberrations were found in 43% of cases. Blake's pouch cysts and megacisterna magna underwent spontaneous resolution in utero in one third of cases and over 90% of survivors without associated anomalies had normal developmental outcome at 1-5 years. Isolated Dandy-Walker malformation and vermian hypoplasia were associated with normal developmental outcome in only 50% of cases.

CONCLUSION

Prenatal neurosonography and MRI are similarly accurate in the categorization of posterior fossa fluid collections from mid gestation. Blake's pouch cyst and megacisterna magna are risk factors for associated anomalies but when isolated have an excellent prognosis, with a high probability of intrauterine resolution and normal intellectual development in almost all cases. Conversely, Dandy-Walker malformation and vermian hypoplasia, even when they appear isolated antenatally, are associated with an abnormal outcome in half of cases.

Magnetic resonance imaging of the fetal central nervous system, head, neck, and chest

Magnetic resonance imaging (MRI) has become an important tool in the assessment of fetal anomalies. Although ultrasound remains the modality of choice for screening, MRI offers several advantages that permit optimal characterization of anomalies in certain situations. Accurate recognition and characterization of fetal anomalies guides decisions about pregnancy management and coordination of postnatal care. This article will briefly review safety and practical aspects of fetal MRI. We will then provide a concise summary of the most common indications for fetal MRI, and discuss the differential diagnosis and role of MRI in assessment of fetal brain, head, neck, spine, and chest anomalies.

Prenatal diagnosis of partial trisomy 3q resulting from t(3;14) in a fetus with multiple anomalies including vermian hypoplasia

While genetic origin of Dandy-Walker complex has not yet fully elucidated, the complex has been known to be associated with structural and chromosomal abnormalities. A partial trisomy 3q was also identified in patients with DWC. 3q duplication syndrome is defined as duplications of large parts of 3q, especially 3q21-qter. Most cases with 3q duplication are diagnosed postnatally and the patients show typical features including various facial dysmorphisms, congenital heart defects, genitourinary malformations, and mental and growth retardation. Here we report a 28 year old nulliparous woman who was referred from the infertility clinic at 21 gestational weeks. Fetal ultrasonographic examination showed various abnormal findings including a ventricular septal defect, hydrocephalus, and hypoplasia of the cerebellar vermis. Fetal chromosome analysis was initially reported as 46,XY,der(14)(?::p11.2→qter). Array CGH followed by FISH allowed precise characterization of the der(14) chromosome and the initial karyotype of the fetus had been changed to 46,XY,add(14)(p11).ish der(14)t(3;14)(q26.1;p11)(tel3q+).arr 3q26.1q29(166249469-199288361)x3. Though further studies are required, gene clusters rather than a single gene might be responsible for the clinical features of the Dandy-Walker complex.

The fetal cerebellum: development and common malformations

The cerebellum undergoes a protracted development, making it particularly vulnerable to a broad spectrum of developmental events. Acquired destructive and hemorrhagic insults may also occur. The main steps of cerebellar development are reviewed. The normal imaging patterns of the cerebellum in prenatal ultrasound and magnetic resonance imaging (MRI) are described with emphasis on the limitations of these modalities. Because of confusion in the literature regarding the terminology used for cerebellar malformations, some terms (agenesis, hypoplasia, dysplasia, and atrophy) are clarified. Three main pathologic settings are considered and the main diagnoses that can be suggested are described: retrocerebellar fluid enlargement with normal or abnormal biometry (Dandy-Walker malformation, Blake pouch cyst, vermian agenesis), partially or globally decreased cerebellar biometry (cerebellar hypoplasia, agenesis, rhombencephalosynapsis, ischemic and/or hemorrhagic damage), partially or globally abnormal cerebellar echogenicity (ischemic and/or hemorrhagic damage, cerebellar dysplasia, capillary telangiectasia). The appropriate timing for performing MRI is also discussed.

Magnetic Resonance Imaging for Detection of Brain Abnormalities in Fetuses with Cleft Lip and/or Cleft Palate

Objective

To determine the prevalence of brain abnormalities identified by prenatal imaging of fetuses with cleft lip with or without cleft palate (CUP) or cleft palate only (CP) and to compare with postnatal imaging and neurologic evaluation.

Design

This was a retrospective review of radiologic images (magnetic resonance imaging [MRI] and sonography) of fetuses diagnosed with CUP or CP at the Advanced Fetal Care Center at Children's Hospital Boston between 2002 and 2008. Images were reviewed for possible brain abnormalities by a pediatric radiologist who specializes in this field. Postnatal imaging was also assessed whenever available and correlated with clinical findings.

Setting

A large, tertiary-care, academic pediatric hospital.

Population

One hundred twenty-six fetuses and 105 corresponding infants.

Results

Brain abnormalities were found in 8 of 126 fetuses (6.3%) by prenatal MRI. The malformations were corpus callosal dysgenesis (n = 3), encephalocele (n = 1), hypoplasia of the cerebellar hemispheres or vermis (n = 3), and white matter neuronal migration anomaly (n = 1). An additional 2 patients were diagnosed with brain abnormalities postnatally that had not been detected on prenatal imaging.

Conclusions

The possibility of brain anomalies should be assessed in a fetus found to have CUP or CP by sonography and/or MRI. Central nervous system imaging and careful neurodevelopmental follow-up is indicated in these infants.

Correlation between pre- and postnatal cerebral magnetic resonance imaging

OBJECTIVES

To evaluate the diagnostic accuracy of fetal cerebral magnetic resonance imaging (MRI) on a large cohort and to compare pre- and postnatal MRI data.

METHODS

This prospective study included all cases referred to our unit for fetal cerebral MRI examination between June 2006 and December 2009 and which underwent at least one postnatal MRI examination. Cases in which there was termination of pregnancy, fetal death or stillbirth were excluded. The pre- and postnatal diagnoses established by MRI were compared and divided into five subgroups: same diagnosis on pre- and postnatal MRI (Group 1); same diagnosis but different appearance related to the natural course of the disease (Group 2); different diagnosis (related to limitations of fetal MRI) (Group 3); same diagnosis but with additional findings discovered on postnatal MRI examination (Group 4); or same diagnosis but different appearance related to the natural course of the disease (as in Group 2) and associated with additional findings discovered on postnatal MRI examination (Group 5). The prognostic impact of a possible disagreement between pre- and postnatal findings was evaluated.

RESULTS

One hundred fetuses were included. Fetal MRI was performed at a mean gestational age of 33 (range, 24-39) weeks and postnatal MRI at a mean age of 3.5 months. There were 53 cases classified as Group 1, 32 in Group 2, four in Group 3, 10 in Group 4 and one in Group 5. Thus, in 15 cases (Groups 3-5), there were discrepancies between pre- and postnatal findings (mostly related to corpus callosum anatomy, cortical and migration disorders). The discrepancy was judged to have a prognostic impact in 9/15 cases. Two postnatal MRI examinations were performed in eight cases, in one of which the second examination showed subependymal heterotopia which were not detectable on the first examination.

CONCLUSION

Pre- and postnatal MRI data showed good agreement in 85% of cases. There was disagreement with a prognostic impact in 9% of cases.

Sonographic examination of the fetal vermis: tricks for obtaining the narrow midline target with 3-dimensional volume contrast imaging in the C plane

Prenatal imaging of the fetal cerebellar vermis is challenging even for experienced examiners. We found that by aiming the ultrasound beam through the mastoid fontanel and then rotating the data set in a multiplanar reconstruction and applying volume contrast imaging in the C plane, we were consistently able to obtain images of the vermis in the standard midsagittal plane. Images of the fetal vermis suitable for morphologic evaluation were obtained in 408 of 414 cases (98.5%) at gestational ages of 18 weeks to 31 weeks 6 days; the examination time was only minimally increased.

Post-mortem cerebral magnetic resonance imaging T1 and T2 in fetuses, newborns and infants

Post-mortem magnetic resonance imaging (PM MRI) of brain is increasingly used in clinical practice; understanding of normal PM contrast to noise ratio (CNR), T1 and T2 values relaxation times is important for optimisation and accurate interpretation of PM MRI.

METHODS

We obtained T1- and T2-weighted images at 1.5 T. In the first phase of the study, we calculated CNR in twelve brain regions in 5 newborn infants after death and compared this with CNR from 5 infants during life. In the second phase, we measured deep grey matter (GM) and white matter (WM) T1 post-mortem in 18 fetuses and T1 and T2 post-mortem 6 infants prior to autopsy.

RESULTS

Phase I: post-mortem T1- and T2-weighted CNRs were lower in most brain regions than during life. Phase II: compared with in vivo, all post-mortem images lacked GM-WM contrast and had high T2-weighted WM signal intensity. Mean (SD) post-mortem T1 in white and deep gray matter were respectively 1898 (327)ms and 1514 (202)ms in fetuses (p>0.05) and 1234 (180)ms and 1016 (161)ms in infants and newborns (p>0.05). Mean (SD) post-mortem T2 was 283 (11)ms in WM and 182 (18)ms in deep GM in infants and newborns (p<0.001).

CONCLUSIONS

Post-mortem T1 and T2 values are higher than those reported from live cases. The difference between T1 values in GM and WM reduce after death.

Magnetic resonance imaging of the fetus

Fetal magnetic resonance imaging (MRI) has become established as part of clinical practice in many centres worldwide especially when visualization of the central nervous system pathology is required. In this review we summarize the recent literature and provide an overview of fetal development and the commonly encountered fetal pathologies visualized with MRI and illustrated with numerous MR images. We aim to convey the role of fetal MRI in clinical practice and its value as an additional investigation alongside ultrasound yet emphasize the need for caution when interpreting fetal MR images especially where experience is limited.

Our clinical experience about prenatal diagnosis and neonatal outcomes of fetal central nervous system anomalies

OBJECTIVE

To present a retrospective analysis of the prenatal diagnosis and the outcome of fetuses diagnosed with central nervous system (CNS) anomalies.

MATERIALS AND METHODS

We reviewed the medical records and ultrasound data of 69 cases diagnosed with CNS anomalies from 2007 to 2008. We described the prenatal diagnosis, associated findings, and outcome of these patients.

RESULTS

Sixty-nine patients were diagnosed with CNS anomalies. Of these, 31 had ventriculomegaly + hydrocephaly, 14 had spina bifida + meningomyelosel, 5 had choroid plexus cyst, 5 had Dandy Walker malformation, 3 had sacrocoxigeal teratoma, 2 had encephalosel, 1 had microcephaly, and 1 had Arnold Chiari malformation. Eight amniocentesis, three cord blood sampling, and two fetal reduction procedure were performed. Nine pregnancy termination and 36 delivery were performed. Neurosurgical correction was performed for neonates with spina bifida, hydrocephaly and sacrocoxigeal teratoma. Twenty-one neonates were discharged with cure, 4 neonates with follow-up, 7 neonates with paraplegia, and 13 neonates died.

CONCLUSION

The outcome of fetuses with CNS anomalies was shown to depend mainly on the degree of neural tube defect and the associated anomalies were the most important factors in surviving.

Posterior fossa malformations: main features and limits in prenatal diagnosis

Posterior fossa (PF) malformations are commonly observed during prenatal screening. Their understanding requires knowledge of the main steps of PF development and knowledge of normal patterns in US and MR imaging. The vast majority of PF malformations can be strongly suspected by acquiring a midline sagittal slice and a transverse slice and by systematically scrutinizing the elements of the PF: cerebellar vermis, hemispheres, brainstem, fourth ventricle, PF fluid spaces and tentorium. Analysis of cerebellar echogenicity and biometry is also useful. This review explains how to approach the diagnosis of the main PF malformations by performing these two slices and answering six key questions about the elements of the PF. The main imaging characteristics of PF malformations are also reviewed.

The intersection of ethics and communication in prenatal imaging: challenges for the pediatric radiologist

Pediatric radiologists who practice prenatal imaging are often at the front lines of communication with pregnant patients and their partners. The communication process is particularly complex when a fetal abnormality is diagnosed. Regardless of whether the information is completely new and unexpected, or the patient is referred for tertiary imaging and counseling, few pediatric radiologists are trained specifically in the communication skills necessary to provide optimal care to the prospective parents. This paper reviews current literature regarding communication with patients about unexpected or difficult information, and illustrates key clinical and ethical features that make conversations with pregnant patients particularly challenging in the setting of fetal abnormalities.

Role of MR imaging in prenatal diagnosis of pregnancies at risk for Joubert syndrome and related cerebellar disorders

BACKGROUND AND PURPOSE

JSRD are rare autosomal recessive brain malformations. We hypothesized that MR imaging can assess fetuses at risk for JSRD and might influence their diagnoses.

MATERIALS AND METHODS

We prospectively performed cranial MR imaging for 12 fetuses (mean GA, 23 weeks; SD, 3.7) at 25% recurrence risk for JSRD. We correlated prenatal MR imaging findings with postnatal MR imaging and clinical outcome. Retrospectively, we compared posterior fossa measurements of the cases with those of 24 age-matched fetuses with proved normal brain MR imaging. Institutional review board approval and consents were obtained. Statistical methods included a t test and ANCOVA tests.

RESULTS

Fetal MR imaging correctly diagnosed 3 cases at 22, 28, and 29 weeks of gestation as JSRD, and 9 cases as normal. In JSRD-affected fetuses, prenatal MR imaging detected narrow pontomesencephalic junction (isthmus) with deepening of the interpeduncular fossa and thick horizontally placed superior cerebellar peduncles (MTS), deformed anteriorly convex floor of the fourth ventricle, and midline cerebellar cleft in place of the hypoplastic vermis. Measurements on axial fetal MR imaging at pontomesencephalic junction, ratio of AP diameters of interpeduncular fossa to midbrain/isthmus, and ratio of the AP to transverse diameters of the fourth ventricle were significantly higher in JSRD-affected fetuses than in nonaffected cases and the control group.

CONCLUSIONS

MR imaging can diagnose JSRD in at-risk pregnancies by detecting posterior fossa signs. Measurements at the pontomesencephalic junction may enhance fetal MR imaging accuracy in diagnosing JSRD.