Static and dynamic responses to hyperoxia of normal placenta across gestation with T2*-weighted sequences.

OBJECTIVES: T2*-weighted sequences have been identified as non-invasive tools to study the placental oxygenation in-vivo. This study aims to investigate both static and dynamic responses to hyperoxia of the normal placenta across gestation. METHODS: We conducted a single-center prospective study including 52 uncomplicated pregnancies. Two T2*-weighted sequences were performed: T2*-relaxometry was performed before and after maternal hyperoxia. The histogram distribution of T2* values was assessed by fitting a gamma distribution as T2*~Γ(αß). A dynamic acquisition (BOLD protocol) was also performed before and during oxygen supply, until placental oxygen saturation. The signal change over time was modeled using a sigmoid function, used to determine the intensity of enhancement (∆BOLD,%), a temporal variation coefficient (λ,min-1 , controlling the slope of the curve), and the maximal steepness (Vmax, ∆BOLD.min-1 ) of placental enhancement. RESULTS: The histogram analysis of the T2* values in normoxia showed a whole-placenta variation, with a decreasing linear trend in the mean T2* value (R= -0.83, 95% CI [-0.9, -0.71], p<0.001) along with a more peaked and narrower distribution of T2* values across gestation. After maternal hyperoxia, the mean T2* ratios (mean T2*hyperoxia / mean T2*baseline ) were positively correlated with gestational age, while the other histogram parameters remained stable, suggesting a translation of the histogram towards higher values with a similar aspect. The ∆BOLD showed a non-linear increase across gestation. Conversely, the λ(min-1 ) parameter, showed an inverted trend across gestation, with a significantly weaker correlation (R = -0.33, 95% CI [-0.58, -0.02], p=0.04, R2 = 0.1). As a combination of ∆BOLD and λ, the changes in Vmax throughout gestation were mainly influenced by the changes in ∆BOLD and resulted in a positive non-linear correlation with gestational age. CONCLUSION: Our results suggest that the decrease in the T2* placental signal over gestation does not reflect a dysfunction. The BOLD effect, representative of a free-diffusion model of oxygenation, highlights the growing differences in oxygen saturation between mother and fetus across gestation (∆BOLD), and placental permeability to oxygen (λ). This article is protected by copyright. All rights reserved.

Placental T2* and BOLD effect in response to hyperoxia in normal and growth-restricted pregnancies: multicenter cohort study.

OBJECTIVES: Blood-oxygen-level-dependent (BOLD) magnetic resonance imaging (MRI) facilitates the non-invasive in-vivo evaluation of placental oxygenation. The aims of this study were to identify and quantify a relative BOLD effect in response to hyperoxia in the human placenta and to compare it between pregnancies with and those without fetal growth restriction (FGR). METHODS: This was a prospective multicenter study (NCT02238301) of 19 pregnancies with FGR (estimated fetal weight (EFW) on ultrasound < 5th centile) and 75 non-FGR pregnancies (controls) recruited at two centers in Paris, France. Using a 1.5-Tesla MRI system, the same multi-echo gradient-recalled echo (GRE) sequences were performed at both centers to obtain placental T2* values at baseline and in hyperoxic conditions. The relative BOLD effect was calculated according to the equation 100 × (hyperoxic T2* - baseline T2*)/baseline T2*. Baseline T2* values and relative BOLD effect were compared according to EFW (FGR vs non-FGR), presence/absence of Doppler anomalies and birth weight (small-for-gestational age (SGA) vs non-SGA). RESULTS: We observed a relative BOLD effect in response to hyperoxia in the human placenta (median, 33.8% (interquartile range (IQR), 22.5-48.0%)). The relative BOLD effect did not differ significantly between pregnancies with and those without FGR (median, 34.4% (IQR, 24.1-48.5%) vs 33.7% (22.7-47.4%); P = 0.95). Baseline T2* Z-score adjusted for gestational age at MRI was significantly lower in FGR pregnancies compared with non-FGR pregnancies (median, -1.27 (IQR, -4.87 to -0.10) vs 0.33 (IQR, -0.81 to 1.02); P = 0.001). Baseline T2* Z-score was also significantly lower in those pregnancies that subsequently delivered a SGA neonate (n = 23) compared with those that delivered a non-SGA neonate (n = 62) (median, -0.75 (IQR, -3.48 to 0.29) vs 0.35 (IQR, -0.79 to 1.05); P = 0.01). CONCLUSIONS: Our study confirms a BOLD effect in the human placenta and that baseline T2* values are significantly lower in pregnancies with FGR. Further studies are needed to evaluate whether such parameters may detect placental insufficiency before it has a clinical impact on fetal growth. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Quantitative fetal MRI with diffusion tensor imaging in cases with 'short' corpus callosum.

OBJECTIVES: It has been suggested previously that the presence of Probst bundles (PB) in cases with a short corpus callosum (SCC) on diffusion tensor imaging (DTI) may help to differentiate between corpus callosal (CC) dysplasia and a variant of normal CC development. The objectives of this study were to compare DTI parameters between cases of SCC vs normal CC and between cases of SCC with PB (SCC-PB+) vs SCC without PB (SCC-PB-). METHODS: This was a retrospective study of patients referred to the Necker Hospital in Paris, France, for magnetic resonance imaging (MRI) evaluation of an apparently isolated SCC detected by sonography between November 2016 and December 2022 (IRB: 00011928). MRI was performed using a 1.5-Tesla Signa system. T2-weighted axial and sagittal sequences of the fetal brain were used to measure the length and thickness of the CC. 16-direction DTI axial brain sequences were performed to identify the presence of PB and to generate quantitative imaging parameters (fractional anisotropy (FA) and apparent diffusion coefficient (ADC)) of the entire CC, genu, body and splenium. Cases in which other associated brain abnormalities were detected on MRI were excluded. Cases were matched for fetal gender and gestational age with controls in a 1:3 ratio. Control cases were normal fetuses included in the LUMIERE on the FETUS trial (NCT04142606) that underwent the same DTI evaluation of the brain. Comparisons between SCC and normal CC cases, and between SCC-PB+ and SCC-PB- cases were performed using ANOVA and adjusted for potential confounders using ANCOVA. RESULTS: Twenty-two SCC cases were included and compared with 66 fetuses with a normal CC. In 10/22 (45.5%) cases of SCC, PB were identified. As expected, dimensions of the CC were significantly smaller in SCC compared with normal CC cases (all P < 0.01). In SCC-PB+ vs SCC-PB- cases, FA values were significantly lower in the entire CC (median, 0.21 (range, 0.19-0.24) vs 0.24 (range, 0.22-0.28); P < 0.01), genu (median, 0.21 (range, 0.15-0.29) vs 0.24 (range, 0.17-0.29); P = 0.04), body (median, 0.21 (range, 0.18-0.23) vs 0.23 (range, 0.21-0.27); P = 0.04) and splenium (median, 0.22 (range, 0.16-0.30) vs 0.25 (range, 0.20-0.29); P = 0.03). ADC values were significantly higher in the entire CC, genu and body in SCC-PB+ vs SCC-PB- cases (all P < 0.05). In SCC-PB+ cases, all FA values were significantly lower, and ADC values in the CC body were significantly higher compared with normal CC cases (all P < 0.05). In SCC-PB- cases, there was no significant difference in FA and ADC compared with normal CC cases (all P > 0.05). CONCLUSIONS: Fetal DTI evaluation of the CC showed that FA values were significantly lower and ADC values tended to be significantly higher in SCC-PB+ compared with normal CC cases. This may highlight alterations of the white matter microstructure in SCC-PB+. In contrast, isolated SCC-PB- did not demonstrate significant changes in DTI parameters, strengthening the possibility that this is a normal CC variant. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Corpus callosal reference ranges: systematic review of methodology of biometric chart construction and measurements obtained.

OBJECTIVE: Adequate reference ranges of size of the corpus callosum (CC) are necessary to improve characterization of CC abnormalities and parental counseling. The objective of this study was to evaluate the methodology used in studies developing references charts for CC biometry. METHODS: We conducted a systematic review of studies on fetal CC biometry using a set of predefined quality criteria of study design, statistical analysis and reporting methods. We included observational studies whose primary aim was to create ultrasound or magnetic resonance imaging charts for CC size in a normal population of fetuses. Studies were scored against a predefined set of independently agreed methodological criteria, and an overall quality score was given for each study. RESULTS: Twelve studies met the inclusion criteria. Quality scores ranged between 17.4% and 95.7%. The greatest potential for bias was noted for the following items: sample selection and sample-size calculation, as only 17% of the studies were population-based and had consecutive or random recruitment of patients and with a justification of the sample size; number of measurements obtained for CC biometry, as only 17% of the studies performed more than one measurement per fetus and per scan; and description of characteristics of the study population, as only 8% of the studies clearly reported a minimum dataset of demographic characteristics. CONCLUSIONS: Our review demonstrates substantial heterogeneity in methods and final biometric values of the fetal CC across the evaluated studies. The use of uniform methodology of the highest quality is essential in order to define a 'short' CC and provide appropriate parental counseling. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Diffusion tensor imaging of fetal spinal cord: feasibility and gestational-age-related changes.

OBJECTIVES: Diffusion tensor imaging (DTI) of the fetal brain is a relatively new technique that allows evaluation of white matter tracts of the central nervous system throughout pregnancy, as well as in certain pathological conditions. The objectives of this study were to evaluate the feasibility of DTI of the spinal cord in utero and to examine gestational-age (GA)-related changes in DTI parameters during pregnancy. METHODS: This was a prospective study conducted between December 2021 and June 2022 in the LUMIERE Platform, Necker-Enfants Malades Hospital, Paris, France, as part of the LUMIERE SUR LE FETUS trial. Women with a pregnancy between 18 and 36 weeks of gestation without fetal or maternal abnormality were eligible for inclusion. Sagittal diffusion-weighted scans of the fetal spine were acquired, without sedation, using a 1.5-Tesla magnetic resonance imaging scanner. The imaging parameters were as follows: 15 non-collinear direction diffusion-weighted magnetic-pulsed gradients with a b-value 700 s/mm2 and one B0 image without diffusion-weighting; slice thickness, 3 mm; field of view (FOV), 36 mm; phase FOV, 1.00; voxel size, 4.5 × 2.8 × 3 mm3 ; number of slices, 7-10; repetition time, 2800 ms; echo time, minimum; and total acquisition time, 2.3 min. DTI parameters, including fractional anisotropy (FA) and apparent diffusion coefficient (ADC), were extracted at the cervical, upper thoracic, lower thoracic and lumbar levels of the spinal cord. Cases with motion degradation and those with aberrant reconstruction of the spinal cord on tractography were excluded. Pearson's correlation analysis was performed to evaluate GA-related changes of DTI parameters during pregnancy. RESULTS: During the study period, 42 pregnant women were included at a median GA of 29.3 (range, 22.0-35.7) weeks. Five (11.9%) patients were not included in the analysis because of fetal movement. Two (4.8%) patients with aberrant tractography reconstruction were also excluded from analysis. Acquisition of DTI parameters was feasible in all remaining cases (35/35). Increasing GA correlated with increasing FA averaged over the entire fetal spinal cord (r, 0.37; P < 0.01), as well as at the individual cervical (r, 0.519; P < 0.01), upper thoracic (r, 0.468; P < 0.01), lower thoracic (r, 0.425; P = 0.02) and lumbar (r, 0.427; P = 0.02) levels. There was no correlation between GA and ADC averaged over the entire spinal cord (r, 0.01; P = 0.99) or at the individual cervical (r, -0.109; P = 0.56), upper thoracic (r, -0.226; P = 0.22), lower thoracic (r, -0.052; P = 0.78) or lumbar (r, -0.11; P = 0.95) levels. CONCLUSIONS: This study shows that DTI of the spinal cord is feasible in normal fetuses in typical clinical practice and allows extraction of DTI parameters of the spinal cord. There is a significant GA-related change in FA in the fetal spinal cord during pregnancy, which may result from decreasing water content as observed during myelination of fiber tracts occurring in utero. This study may serve as a basis for further investigation of DTI in the fetus, including research into its potential in pathological conditions that impact spinal cord development. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Diffusion tensor imaging of fetal brain: principles, potential and limitations of promising technique.

Human brain development is a complex process that begins in the third week of gestation. During early development, the fetal brain undergoes dynamic morphological changes. These changes result from events such as neurogenesis, neuronal migration, synapse formation, axonal growth and myelination. Disruption of any of these processes is thought to be responsible for a wide array of different pathologies. Recent advances in magnetic resonance imaging, especially diffusion-weighted imaging and diffusion tensor imaging (DTI), have enabled characterization and evaluation of brain development in utero. In this review, aimed at practitioners involved in fetal medicine and high-risk pregnancies, we provide a comprehensive overview of fetal DTI studies focusing on characterization of early normal brain development as well as evaluation of brain pathology in utero. We also discuss the reliability and limitations of fetal brain DTI. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal diagnosis and outcome of fetuses with isolated agenesis of septum pellucidum: cohort study and meta-analysis.

OBJECTIVE: To evaluate the postnatal outcome of children with a prenatal diagnosis of apparently isolated agenesis of the septum pellucidum (ASP). METHODS: A retrospective cohort study of cases of prenatally diagnosed ASP followed in two tertiary centers and a meta-analysis combining data from the cohort study with data from published studies identified in a systematic review were carried out. Only cases with apparently isolated ASP on antenatal ultrasound and/or magnetic resonance imaging and with available postnatal follow-up data were considered eligible for inclusion. The following outcomes were analyzed: incidence of chromosomal anomalies, agreement between antenatal and postnatal findings, overall incidence of septo-optic dysplasia (SOD) and incidence of major neurological disability (motor, language, coordination or behavioral disorder or epilepsy) in non-SOD children. The incidence of SOD in infants with apparently normal optic pathways on antenatal imaging was also evaluated. RESULTS: Fifteen cases of isolated ASP, with median postnatal follow-up of 36 months (range, 12-60 months), were selected from the two centers. Six previously published studies met the inclusion criteria for the systematic review and a total of 78 cases were eligible for the analysis, including the 15 cases from our series. Genetic tests were carried out antenatally in 30 fetuses, of which two had an abnormal result (pooled proportion, 9.0% (95% CI, 1.8-20.7%); I2 = 0%). Additional or discordant imaging findings were noted postnatally in 9/70 (pooled proportion, 13.7% (95% CI, 3.5-29.0%); I2 = 63.9%) cases. Of all 78 neonates with available follow-up, SOD was diagnosed postnatally in 14 (pooled proportion, 19.4% (95% CI, 8.6-33.2%); I2 = 51.2%). In 60 cases, the optic pathways were considered to be normal on antenatal imaging, and six of these (pooled proportion, 9.1% (95% CI, 1.1-24.0%); I2 = 62.0%) were diagnosed postnatally with SOD. Of the 46 infants with available neurological follow-up who were not affected by SOD, a major neurological disability was diagnosed in three (pooled proportion, 6.5% (95% CI, 0.5-18.6%); I2 = 40.1%). CONCLUSIONS: In the vast majority of cases with a prenatal diagnosis of apparently isolated ASP, the prognosis is favorable. However, an additional anomaly is detected after birth in about 14% of cases and has a negative impact on clinical outcome. Detailed antenatal assessment of the brain and optic pathways is strongly recommended in order to identify the presence of associated anomalies. Antenatal visualization of apparently normal optic pathways does not rule out SOD. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Feasibility and Added Value of Fetal DTI Tractography in the Evaluation of an Isolated Short Corpus Callosum: Preliminary Results.

BACKGROUND AND PURPOSE: Prognosis of isolated short corpus callosum is challenging. Our aim was to assess whether fetal DTI tractography can distinguish callosal dysplasia from variants of normal callosal development in fetuses with an isolated short corpus callosum. MATERIALS AND METHODS: This was a retrospective study of 37 cases referred for fetal DTI at 30.4 weeks (range, 25-34 weeks) because of an isolated short corpus callosum less than the 5th percentile by sonography at 26 weeks (range, 22-31 weeks). Tractography quality, the presence of Probst bundles, dysmorphic frontal horns, callosal length (internal cranial occipitofrontal dimension/length of the corpus callosum ratio), and callosal thickness were assessed. Cytogenetic data and neurodevelopmental follow-up were systematically reviewed. RESULTS: Thirty-three of 37 fetal DTIs distinguished the 2 groups: those with Probst bundles (Probst bundles+) in 13/33 cases (40%) and without Probst bundles (Probst bundles-) in 20/33 cases (60%). Internal cranial occipitofrontal dimension/length of the corpus callosum was significantly higher in Probst bundles+ than in Probst bundles-, with a threshold value determined at 3.75 for a sensitivity of 92% (95% CI, 77%-100%) and specificity of 85% (95% CI, 63%-100%). Callosal lipomas (4/4) were all in the Probst bundles- group. More genetic anomalies were found in the Probst bundles+ than in Probst bundles- group (23% versus 10%, P = .08). CONCLUSIONS: Fetal DTI, combined with anatomic, cytogenetic, and clinical characteristics could suggest the possibility of classifying an isolated short corpus callosum as callosal dysplasia and a variant of normal callosal development.

Heterogeneity in defining fetal corpus callosal pathology: systematic review.

OBJECTIVE: Fetal anomalies of the corpus callosum (CC) have been reported in the prenatal imaging literature since 1985, and, especially when isolated, pose challenges for both the patient and fetal medicine specialist. The purpose of this study was to review systematically the literature on prenatally diagnosed abnormalities of the CC, focusing on the terminology used to describe abnormalities other than complete agenesis of the CC, and to assess the heterogeneity of the nomenclature and definitions used. METHODS: This study was conducted in accordance with the PRISMA statement for reporting systematic reviews. A literature search was performed to identify prospective or retrospective case series or cohort studies, published in English, French, Italian, German or Spanish, reporting fetal imaging findings and describing anomalies of the CC. Quality and risk of bias of the studies were evaluated using the Newcastle-Ottawa scale and a modification of the scale developed by Conde-Agudelo et al. for other fetal imaging studies. The data extracted included the number of patients, the number of different anomalies identified, the descriptive names of the anomalies, and, where applicable, the definitions of the anomalies, the number of cases of each type of anomaly and the biometric charts used. Secondary tests used to confirm the diagnosis, as well as the postnatal or post-termination tests used to ascertain the diagnosis, were also recorded. RESULTS: The search identified 998 records, and, after review of titles and abstracts and full review of 45 papers, 27 studies were included initially in the review, of which 24 were included in the final analysis. These 24 studies had a broad range of quality and risk of bias and represented 1135 cases of CC anomalies, of which 49% were complete agenesis and the remainder were described using the term partial agenesis or nine other terms, of which five had more than one definition. CONCLUSIONS: In comparison to the postnatal literature, in the prenatal literature there is much greater heterogeneity in the nomenclature and definition of CC anomalies other than complete agenesis. This heterogeneity and lack of standard definitions in the prenatal literature make it difficult to develop large multicenter pooled cohorts of patients who can be followed in order to develop a better understanding of the genetic associations and neurodevelopmental and psychological outcomes of patients with CC anomalies. As this information is important to improve counseling of these patients, a good first step towards this goal would be to develop a simpler categorization of prenatal CC anomalies that matches better the postnatal literature. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Focal Areas of High Signal Intensity in Children with Neurofibromatosis Type 1: Expected Evolution on MRI.

BACKGROUND AND PURPOSE: Focal areas of high signal intensity are T2WI/T2-FLAIR hyperintensities frequently found on MR imaging of children diagnosed with neurofibromatosis type 1, often thought to regress spontaneously during adolescence or puberty. Due to the risk of tumor in this population, some focal areas of high signal intensity may pose diagnostic problems. The objective of this study was to assess the characteristics and temporal evolution of focal areas of high signal intensity in children with neurofibromatosis type 1 using long-term follow-up with MR imaging. MATERIALS AND METHODS: We retrospectively examined the MRIs of children diagnosed with neurofibromatosis type 1 using the National Institutes of Health Consensus Criteria (1987), with imaging follow-up of at least 4 years. We recorded the number, size, and surface area of focal areas of high signal intensity according to their anatomic distribution on T2WI/T2-FLAIR sequences. A generalized mixed model was used to analyze the evolution of focal areas of high signal intensity according to age, and separate analyses were performed for girls and boys. RESULTS: Thirty-nine patients (ie, 285 MR images) with a median follow-up of 7 years were analyzed. Focal areas of high signal intensity were found in 100% of patients, preferentially in the infratentorial white matter (35% cerebellum, 30% brain stem) and in the capsular lenticular region (22%). They measured 15 mm in 95% of cases. They appeared from the age of 1 year; increased in number, size, and surface area to a peak at the age of 7; and then spontaneously regressed by 17 years of age, similarly in girls and boys. CONCLUSIONS: Focal areas of high signal intensity are mostly small (<15 mm) abnormalities in the posterior fossa or capsular lenticular region. Our results suggest that the evolution of focal areas of high signal intensity is not related to puberty with a peak at the age of 7 years. Knowledge of the predictive evolution of focal areas of high signal intensity is essential in the follow-up of children with neurofibromatosis type 1.

Neural basis of interindividual variability in social perception in typically developing children and adolescents using diffusion tensor imaging.

Humans show great interindividual variability in the degree they engage in social relationship. The neural basis of this variability is still poorly understood, particularly in children. In this study, we aimed to investigate the neural basis of interindividual variability in the first step of social behavior, that is social perception, in typically developing children. For that purpose, we first used eye-tracking to objectively measure eye-gaze processing during passive visualization of social movie clips in 24 children and adolescents (10.5 ± 2.9 y). Secondly, we correlated eye-tracking data with measures of fractional anisotropy, an index of white matter microstructure, obtained using diffusion tensor imaging MRI. The results showed a large interindividual variability in the number of fixations to the eyes of characters during visualization of social scenes. In addition, whole-brain analysis showed a significant positive correlation between FA and number of fixations to the eyes,mainly in the temporal part of the superior longitudinal fasciculi bilaterally, adjacent to the posterior superior temporal cortex. Our results indicate the existence of a neural signature associated with the interindividual variability in social perception in children, contributing for better understanding the neural basis of typical and atypical development of a broader social expertise.

Refining the prognosis of fetuses infected with Cytomegalovirus in the first trimester of pregnancy by serial prenatal assessment: a single-centre retrospective study.

OBJECTIVE: To define the predictive value (PV) of known prognostic factors of fetal infection with Cytomegalovirus following maternal primary infection <14 weeks of gestation, at different time points of pregnancy: the end of the second trimester; following prenatal magnetic resonance imaging (MRI) at 32 weeks of gestation; and using all ultrasound scans performed in the third trimester (US3rdT). DESIGN: A retrospective study. SETTING: Reference fetal medicine unit. POPULATION: Sixty-two fetuses infected <14 weeks of gestation. METHODS: We defined second-trimester assessment (STA) as the combination of ultrasound findings <28 weeks of gestation and fetal platelet count at cordocentesis. Three groups were defined: normal, extracerebral, and cerebral STA. MAIN OUTCOME MEASURES: For each group, the PV of STA alone, STA + MRI, and STA + US3rdT were assessed retrospectively. Outcome at birth and at follow-up were reported. RESULTS: The STA was normal, and with extracerebral and cerebral features, in 43.5, 42.0, and 14.5%, respectively. The negative PV of normal STA and MRI for moderate to severe sequelae was 100%. The residual risk was unilateral hearing loss in 16.7% of cases. Of pregnancies with cerebral STA, 44% were terminated. Following extracerebral STA, 48% of neonates were symptomatic and 30% had moderate to severe sequelae. In those cases, the positive and negative PV of MRI for sequelae were 33 and 73%, respectively. STA + US3rdT had a lower negative PV than MRI for symptoms at birth and for moderate to severe sequelae. Any false-positive findings at MRI were mostly the result of hypersignals of white matter. CONCLUSIONS: Serial assessment in the second and third trimesters by ultrasound and MRI is necessary to predict the risk of sequelae occurring in 35% of pregnancies following fetal infection in the first trimester of pregnancy. TWEETABLE ABSTRACT: Serial ultrasound prognostic assessment following fetal CMV infection in the 1st trimester is improved by MRI at 32 weeks.

Biometric and morphological features on magnetic resonance imaging of fetal bladder in lower urinary tract obstruction: new perspectives for fetal cystoscopy.

OBJECTIVES: Incompatibility between currently available fetoscopes and the anatomical constraints of the distended fetal bladder, with the resulting curvature around the bladder neck, account for most technical difficulties during fetal cystoscopy in lower urinary tract obstruction (LUTO). The aim of this anatomical study was to assess by magnetic resonance imaging (MRI) the variation in three bladder angles (bladder-neck angle (BNA), vesicourethral angle (VUA) and angle between bladder dome and posterior urethra (DUA)), according to gestational age (GA), bladder volume and the presence of LUTO. METHODS: From our fetal medicine database, we retrieved for review 46 MRI examinations of male fetuses between 2015 and 2019, including 17 with LUTO, examined at a mean GA of 28.1 (range, 17.3-35.0) weeks and 29 age-matched controls, examined at 29.9 (range, 21.9-35.0) weeks. We measured bladder volume, bladder-wall thickness and the three bladder angles, and used the Mann-Whitney U-test to compare values between groups. Variations according to GA and bladder volume were determined using analysis of variance (ANOVA). A reliability study was performed using the Bland-Altman method and Lin's correlation coefficient was calculated. RESULTS: Both bladder volume and bladder-wall thickness were significantly greater in the LUTO group (P < 0.01). BNA was significantly larger in LUTO compared with control fetuses: the mean (range) was 127.1° (101.6-161.6°) vs 111.2° (88.5-157.3°) (P < 0.01). DUA averaged 117° and showed no difference between the groups (P = 0.92). No statistical comparison was performed on VUA since this was not measurable in most control fetuses. ANOVA showed no variation of any angle with bladder volume in both LUTO fetuses and control fetuses. BNA in LUTO fetuses was the only angle to vary with GA, being larger after, compared with at or before, 25 weeks (P = 0.04). The reliability study showed an acceptable bias for both intra- and interobserver reproducibility for all three angles. CONCLUSION: The findings that BNA is increased by approximately 15° in fetuses with LUTO and DUA averages 117° could aid in development of a customized fetal cystoscope and help to overcome the current technical challenges of fetal cystoscopy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Incidental Brain MRI Findings in Children: A Systematic Review and Meta-Analysis.

BACKGROUND: The detection of incidental findings on children's brain MR imaging poses various practical issues because the life-long implications of such findings may be profound. PURPOSE: Our aim was to assess the prevalence and characteristics of incidental brain MR imaging findings in children. DATA SOURCES: Electronic databases (PubMed, EMBASE, and Cochrane) were searched for articles published between 1985 to July 2018, with the following search terms: "incidental," "findings," "brain," "MR imaging." STUDY SELECTION: Inclusion criteria were the following: 1) patients younger than 21 years of age, 2) healthy children without any clinical condition, 3) MR images obtained with at least a 1.5T magnet, 4) original articles, and 5) a methodologic quality score of ≥10. DATA ANALYSIS: Two observers independently extracted data and assessed data quality and validity. The number and type of incidental findings were pooled. Heterogeneity was assessed using the Cochran Q statistic and the I2 statistic. DATA SYNTHESIS: Seven studies were included, reporting 5938 children (mean age, 11.3 ± 2.8 years). Incidental findings were present in 16.4% (99% CI, 9.8-26.2; Q = 117.5, I2= 94.9%) of healthy children, intracranial cysts being the most frequent (10.2%, 99% CI, 3.1-28.5; Q = 306.4, I2 = 98.0%). Nonspecific white matter hyperintensities were reported in 1.9% (99% CI, 0.2-16.8; Q = 73.6, I2 = 94.6%), Chiari 1 malformation was found in 0.8% (99% CI, 0.5-1.3; Q = 7.6, I2 = 60.5%), and intracranial neoplasms were reported in 0.2% (99% CI, 0.1-0.6; Q = 3.4, I2 = 12.3%). In total, the prevalence of incidental findings needing follow-up was 2.6% (99% CI, 0.5-11.7; Q = 131.2, I2 = 95.4%). Incidental findings needing specific treatment were brain tumors (0.2%) and cavernomas (0.2%). LIMITATIONS: Limitations were no age stratification or ethnicity data and variation in the design of included studies. CONCLUSIONS: The prevalence of incidental findings is much more frequent in children than previously reported in adults, but clinically meaningfull incidental findings were present in <1 in 38 children.

CT and Multimodal MR Imaging Features of Embryonal Tumors with Multilayered Rosettes in Children.

BACKGROUND AND PURPOSE: Embryonal tumors with multilayered rosettes, C19MC-altered, are brain tumors occurring in young children, which were clearly defined in the 2016 World Health Organization classification of central nervous system neoplasms. Our objective was to describe the multimodal imaging characteristics of this new entity. MATERIALS AND METHODS: We performed a retrospective monocentric review of embryonal brain tumors and looked for embryonal tumors with multilayered rosettes with confirmed C19MC alteration. We gathered morphologic imaging data, as well as DWI and PWI data (using arterial spin-labeling and DSC). RESULTS: We included 16 patients with a median age of 2 years 8 months. Tumors were both supratentorial (56%, 9/16) and infratentorial (44%, 7/16). Tumors were large (median diameter, 59 mm; interquartile range, 48-71 mm), with absent (75%, 12/16) or minimal (25%, 4/16) peritumoral edema. Enhancement was absent (20%, 3/15) or weak (73%, 11/15), whereas intratumoral macrovessels were frequently seen (94%, 15/16) and calcifications were present in 67% (10/15). Diffusion was always restricted, with a minimal ADC of 520 mm2/s (interquartile range, 495-540 mm2/s). Cerebral blood flow using arterial spin-labeling was low, with a maximal CBF of 43 mL/min/100 g (interquartile range, 33-55 mL/min/100 g 5). When available (3 patients), relative cerebral blood volume using DSC was high (range, 3.5-5.8). CONCLUSIONS: Embryonal tumors with multilayered rosettes, C19MC-altered, have characteristic imaging features that could help in the diagnosis of this rare tumor in young children.