Subtle findings on fetal brain imaging in CMV infected pregnancies: What is the clinical significance? A retrospective analysis with outcome correlation

Brain Metabolite Differences in Fetuses With Cytomegalovirus Infection: A Magnetic Resonance Spectroscopy Study

BACKGROUND

Cytomegalovirus (CMV) is the most common intrauterine infection and may be associated with unfavorable outcomes. While some CMV-infected fetuses may show gross or subtle brain abnormalities on MRI, their clinical significance may be unclear. Conversely, normal development cannot be guaranteed in CMV-infected fetuses with normal MRI.

PURPOSE

To assess brain metabolite differences in CMV-infected fetuses using magnetic resonance spectroscopy (MRS).

STUDY TYPE

Retrospective.

SUBJECTS

Out of a cohort of 149 cases, 44 with maternal CMV infection, amniocentesis results, and good-quality MRS were included. CMV-infected fetuses with positive polymerase chain reaction (PCR) (N = 35) were divided based on MRI results as follows: typical brain abnormalities (gross findings, N = 8), exclusive white matter hyperintense signal (WMHS) on T2-weighted images (subtle findings, N = 7), and normal MRI (N = 20). Uninfected fetuses (negative PCR) with normal MRI were included as controls (N = 9).

FIELD STRENGTH

3 T, T2-weighted half Fourier single-shot turbo spin-echo (HASTE), T2-weighted true fast imaging with steady-state free precession (TrueFISP), T1- and T2*-weighted fast low angle shot (FLASH), and 1H-MRS single-voxel point resolved spectroscopy (PRESS) sequences.

ASSESSMENT

MRI findings were assessed by three radiologists, and metabolic ratios within the basal ganglia were calculated using LCModel.

STATISTICAL TESTS

Analysis of covariance test with Bonferroni correction for multiple comparisons was used to compare metabolic ratios between groups while accounting for gestational age. A P-value <0.05 was deemed significant.

RESULTS

MRS was successfully acquired in 63% of fetuses. Substantial agreement was observed between radiologists (Fleiss' kappa [k] = 0.8). Infected fetuses with gross MRI findings exhibited significantly reduced tNAA/tCr ratios (0.64 ± 0.08) compared with infected fetuses with subtle MRI findings (0.85 ± 0.19), infected fetuses with normal MRI (0.8 ± 0.14) and controls (0.81 ± 0.15). No other significant differences were detected (P ≥ 0.261).

CONCLUSION

Reduced tNAA/tCr within the apparently normal brain tissue was detected in CMV-infected fetuses with gross brain abnormalities, suggesting extensive brain damage. In CMV-infected fetuses with isolated WMHS, no damage was detected by MRS.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 3.

What are the neurodevelopmental outcomes of children with asymptomatic congenital cytomegalovirus infection at birth? A systematic literature review

Congenital cytomegalovirus (cCMV) is among the most common congenital infections globally. Of 85%-90% cCMV-infected infants without symptoms at birth, 10%-15% develop sequelae, most commonly sensorineural hearing loss (SNHL); their childhood neurodevelopmental outcomes are less well understood. Embase and MEDLINE were searched for publications from 16th September 2016 to 9th February 2024 to identify studies reporting primary data on neurodevelopmental outcomes in children with asymptomatic cCMV (AcCMV), measured using assessment tools or as evaluated by the study investigators, clinicians, educators, or parents. The Newcastle-Ottawa scale was applied to studies to assess risk of bias. Of 28 studies from 18 mostly high-income countries, there were 5-109 children with AcCMV per study and 6/28 had a mean or median age at last follow-up of ≥5 years. Children with AcCMV had better neurodevelopmental outcomes than children with symptomatic cCMV in 16/19 studies. Of 9/28 studies comparing AcCMV with CMV-uninfected children, six reported similar outcomes whilst three reported differences limited to measures of full-scale intelligence and receptive vocabulary among children with AcCMV and SNHL, or more generally in motor impairment. Common limitations of studies for our question were a lack of cCMV-uninfected controls, heterogeneous definitions of AcCMV, lack of focus on neurodevelopment, selection bias and inadequate follow-up. There was little evidence of children with AcCMV having worse neurodevelopmental outcomes than CMV-uninfected children, but this conclusion is limited by study characteristics and quality; findings highlight the need for well-designed and standardised approaches to investigate long-term sequelae.

Congenital Cytomegalovirus Infection With Isolated "Minor" Lesions at Fetal Magnetic Resonance Imaging: Long-Term Neurological Outcome

BACKGROUND

The prognostic relevance of fetal/early postnatal magnetic resonance (MR) imaging (MRI) isolated "minor" lesions in congenital cytomegalovirus (CMV) infection is still unclear, because of the heterogeneity of previously reported case series. The aim of this study was to report the imaging and long-term clinical follow-up data on a relatively large cohort of infected fetuses.

METHODS

Among 140 CMV-infected fetuses from a single-center 12-year-long fetal MRI database, cases that showed isolated "minor" lesions at MRI, mainly represented by polar temporal lesions, were selected. MRI features were described, and clinical follow-up information was collected through consultation of medical records and telephone interview to establish the auditory and neurological outcome of each patient.

RESULTS

Thirty-six cases were included in the study. The frequency of "minor" lesions increased progressively with ongoing gestational age in cases who underwent serial MR examination; 31% of cases were symptomatic at birth for unilateral altered auditory brainstem response. At long-term clinical follow-up, performed in 35 patients at a mean age of 64.5 months (range: 25 to 138), 43% of patients were asymptomatic and 57% presented with mild/moderate disability including hearing loss (34%), unilateral in all cases but one (therefore classified as severe), and/or minor cognitive and behavioral disorders (49%).

CONCLUSIONS

Descriptive analysis of the type and modality of occurrence of "minor" lesions suggests performing serial fetal/postnatal MR examinations not to miss later-onset lesions. Follow-up data from the present cohort, combined with maternal/fetal factors and serologic-laboratory parameters may contribute to improve prenatal and neonatal period counselling skills.

Does fetal cerebral magnetic resonance imaging have additional value in cytomegalovirus fetopathy with normal neurosonography?

Linked article: This Correspondence comments on Di Mascio et al. Click here to view the article.

Ultrasonographic Signs of Cytomegalovirus Infection in the Fetus-A Systematic Review of the Literature

BACKGROUND

congenital cytomegalovirus (cCMV) infection during pregnancy is a significant risk factor for fetal and neonatal morbidity and mortality. CMV detection is based on the traditional ultrasound (US) and MRI (magnetic resonance) approach.

METHODS

the present review used the PRISMA protocol for identification of studies associated with CMV infection and sonographic analysis. Various search terms were created using keywords which were used to identify references from Medline, Pubmed, PsycInfo, Scopus and Web of Science.

RESULTS

sonographic analysis of the cCMV infection identified several of the key features associated with fetuses. The presence of abnormal patterns of periventricular echogenicity, ventriculomegaly and intraparenchymal calcifications is indicative of CMV infection in the fetus. Hyperechogenic bowels were seen frequently. These results correlate well with MRI data, especially when targeted transvaginal fetal neurosonography was carried out.

CONCLUSIONS

ultrasonography is a reliable indicator of fetal anomalies, due to cCMV. Fetal brain and organ changes are conclusive indications of infection, but many of the ultrasonographic signs of fetal abnormality could be due to any viral infections; thus, further research is needed to demarcate CMV infection from others, based on the ultrasonographic approach. CMV infection should always be an indication for targeted fetal neurosonography, optimally by the transvaginal approach.

Halo sign in fetal cytomegalovirus infection: cerebral imaging abnormalities and postmortem histopathology in 35 infected fetuses

OBJECTIVE

To evaluate the correlation of periventricular echogenic halo (halo sign) with histopathological findings and its association with other brain imaging abnormalities in fetuses with cytomegalovirus (CMV) infection.

METHODS

This was a retrospective study of fetuses diagnosed with severe CMV infection based on central nervous system (CNS) abnormalities seen on ultrasound, which had termination of pregnancy (TOP) or fetal demise at a single center from 2006 to 2021. All included cases had been evaluated by conventional complete fetal autopsy. A maternal-fetal medicine expert reanalyzed the images from the transabdominal and transvaginal neurosonography scans, blinded to the histological findings. The halo sign was defined as the presence of homogeneous periventricular echogenicity observed in all three fetal brain orthogonal planes (axial, parasagittal and coronal). Cases were classified according to whether the halo sign was the only CNS finding (isolated halo sign) or concomitant CNS anomalies were present (non-isolated halo sign). An expert fetal radiologist reanalyzed magnetic resonance imaging (MRI) examinations when available, blinded to the ultrasound and histological results. Hematoxylin-eosin-stained histologic slides were reviewed independently by two experienced pathologists blinded to the neuroimaging results. Ventriculitis was classified into four grades (Grades 0-3) according to the presence and extent of inflammation. Brain damage was categorized into two stages (Stage I, mild; Stage II, severe) according to the histopathological severity and progression of brain lesions.

RESULTS

Thirty-five CMV-infected fetuses were included in the study, of which 25 were diagnosed in the second and 10 in the third trimester. One fetus underwent intrauterine demise and TOP was carried out in 34 cases. The halo sign was detected on ultrasound in 32 (91%) fetuses (23 in the second trimester and nine in the third), and it was an isolated sonographic finding in six of these cases, all in the second trimester. The median gestational age at ultrasound diagnosis of the halo sign was similar between fetuses in which this was an isolated and those in which it was a non-isolated CNS finding (22.6 vs 24.4 weeks; P = 0.10). In fetuses with a non-isolated halo sign, the severity of additional ultrasound findings was not associated with the trimester at diagnosis, except for microencephaly, which was more frequent in the second compared with the third trimester (10/18 (56%) vs 1/8 (13%); P = 0.04). With respect to histopathological findings, ventriculitis was observed in all fetuses with an isolated halo sign, but this was mild (Grade 1) in the majority of cases (4/6 (67%)). Extensive ventriculitis (Grade 2 or 3) was more frequent in fetuses with a non-isolated halo sign (21/26 (81%)) and those without a periventricular echogenic halo (2/3 (67%); P = 0.032). All fetuses with an isolated halo sign were classified as histopathological Stage I with no signs of brain calcifications, white-matter necrosis or cortical injury. On the other hand, 25/26 fetuses with a non-isolated halo sign and all three fetuses without a periventricular echogenic halo showed severe brain lesions and were categorized as histopathological Stage II. Among fetuses with a non-isolated halo, histological brain lesions did not progress with gestational age, although white-matter necrosis was more frequent, albeit non-significantly, in fetuses diagnosed in the second vs the third trimester (10/15 (67%) vs 3/11 (27%); P = 0.06).

CONCLUSIONS

In CMV-infected fetuses, an isolated periventricular echogenic halo was observed only in the second trimester and was associated with mild ventriculitis without signs of white-matter calcifications or necrosis. When considering pregnancy continuation, detailed neurosonographic follow-up complemented by MRI examination in the early third trimester is indicated. The prognostic significance of the halo sign as an isolated finding is still to be determined. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Predicting Outcome of Congenital Cytomegalovirus Infection by Differentiating and Revisiting Severe versus Mild Prenatal Imaging Features

INTRODUCTION

Our objective was to evaluate the outcome of fetuses with first- and second-trimester fetal cytomegalovirus infection (CMVi) according to prenatal imaging patterns, especially fetuses presenting with mild imaging features (MF), being currently of uncertain prognosis.

MATERIAL AND METHODS

In a retrospective study of 415 suspected CMVi cases, 59 cases were confirmed. Among prenatal imaging features, microcephaly, cortical disorder, and cerebellar hypoplasia as well as severe IUGR and fetal hydrops were considered as severe imaging features (SF). Other imaging features were considered as MF. Postnatal outcome was classified as "normal outcome," "mild sequelae" characterized mainly by sensorineural disorder (SND) and "severe sequelae" characterized by cognitive impairment.

RESULTS

Only first-trimester (T1) and second-trimester (T2) CMVi cases were included in our study (n = 49) since all third-trimester cases (n = 10) had normal imaging and outcome. Sixteen fetuses had normal prenatal imaging and normal outcome, except one showing SND. Abnormal ultrasound findings were present in 33 fetuses, including SF noted in 16 fetuses, related exclusively to first-trimester CMVi. Termination of pregnancy was performed in 18 cases. Twelve first-trimester infected fetuses presented SF, whereas 6 fetuses (T1: n = 5, T2: n = 1) presented isolated MF. Four fetal deaths were encountered. Live-born babies with abnormal imaging included 10 fetuses with MF and one with SF. Among the 10 live babies with isolated MF, SND was encountered in 5 cases, whereas 5 children demonstrated normal outcome. Overall, 50% of our babies showing MF suffered from SND. No case of cognitive disorders was reported in babies showing only MF.

CONCLUSION

SF were encountered only in first-trimester CMVi and should be distinguished from MF. Among our 10 live babies with prenatal MF following first- or second-trimester infection, 50% showed SND, whereas none presented severe sequelae. In 16 fetuses displaying normal fetal imaging, SND was encountered in one first-trimester case (6%).

The Role of Fetal Brain Magnetic Resonance Imaging in Current Fetal Medicine

In open spina bifida we studied the use of MRI for the assessment of the posterior fossa and prevalence of supratentorial anomalies before and after in utero repair. New postprocessing techniques were applied to evaluate fetal brain development in this population compared to controls. In fetuses with congenital diaphragmatic hernia, we evaluated the brain development in comparison to controls. Diffusion weighted imaging was applied to study difference between fetuses with proven first trimester cytomegalovirus infection and controls. Finally, we investigated the value of third trimester fetal brain MRI after treatment for complicated monochorionic diamniotic pregnancies.

Emerging Concepts in Congenital Cytomegalovirus

Over a century of research has focused on improving our understanding of congenital cytomegalovirus (cCMV), yet it remains the most common congenital infection in the United States, affecting 3 to 6 per 1000 live born infants each year. Pregnancies affected by cCMV are at a heightened risk of spontaneous abortion and intrauterine fetal demise. Neonates born with cCMV are also at substantial risk for long-term neurodevelopmental sequelae and disability, including sensorineural hearing loss, even those born without clinically apparent disease. Considerable progress has been made in recent years in study of the epidemiology and transmission of cCMV, developing better diagnostic strategies, implementing newborn screening programs, improving therapeutics, and launching vaccine trials. In this article, we review recent developments in the understanding of the virology and immunobiology of cytomegalovirus. We further discuss how this knowledge informs our understanding of the pathophysiology of cCMV and directs strategies aimed at improving outcomes and quality of life for congenitally infected children. We also provide an update on the epidemiology of cCMV in the United States, evolving scientific understanding of maternal-fetal transmission, enhanced screening approaches, and recognition of neonatal and long-term sequelae. Finally, we review the current landscape of pediatric cCMV research and provide recommendations for novel and high-priority areas for future investigation.

Quantitative and qualitative analysis of fetal temporal lobe T2 signal in cytomegalovirus infected fetuses and normal controls

Background

Temporal lobe T2 hyperintensity has been described in association with prenatal cytomegalovirus (CMV) infection on fetal MRI. However, these findings are often perplexing with high inter-observer variability. Our objective was to evaluate temporal lobe T2 signal quantitatively in prenatal CMV infection.

Methods

In this retrospective study, 119 fetuses, of which 51 fetuses with suspected CMV exposure (29-36 weeks of gestation) based on maternal seroconversion and age-matched 68 normal controls, were included. Mean and maximal temporal lobe T2 signal were evaluated quantitatively by measuring the T2 signal in the temporal lobes relative to the amniotic fluid's signal. Intra-observer, inter-observer variability and diagnostic performance were assessed. The occurrence of neonatal sensorineural hearing loss (SNHL) was recorded.

Results

Relative temporal lobe T2 signal did not change along with the examined gestational age. Of our suspected CMV cohort, 29 fetuses were positive for fetal CMV infection on polymerase chain reaction (PCR) analysis. There were no statistically significant differences in the relative mean or maximal temporal lobes T2 signal between CMV positive, CMV negative fetuses, or normal controls. No correlation was found between neonatal SNHL and temporal lobe T2 signal.

Conclusions

When temporal lobe T2 signal is analyzed quantitatively, CMV infected fetuses do not present an increased signal than age-matched controls. Thus, reported subjective temporal T2 hyperintensities should be interpreted carefully and should have a limited effect on pregnancy management, especially as an isolated finding. Our study illustrates the importance of quantitative imaging in diagnostic neuroradiology.

A unique brain germinal matrix involvement in cytomegalovirus infected fetuses: A retrospective neurosonographic analysis with outcome correlation

OBJECTIVE

To study the clinical significance of brain germinal matrix (GM) changes in cytomegalovirus (CMV) infected fetuses.

METHOD

This is a retrospective analysis. Group A; isolated GM finding, with or without lenticulostriatal vasculopathy (LSV). Group B; non-isolated lesion. Amniocentesis, urinalysis, postnatal US and developmental assessment, were obtained.

RESULTS

Group A and B included 18 and four fetuses, respectively. In group A, mean fetal age at diagnosis was 34.3 weeks (31-38 weeks). In 15/18 (83.3%), the lesion was bilateral and LSV was present in 8/18 (44.4%). Small cysts appeared inside the lesion in 5/18 (27.7%). MRI was normal in 8/18 (44.4%). Subtle or inconclusive findings were reported in the remaining fetuses. Brain ultrasound was normal in 10/18 (55.5%) of newborns. In the remaining, caudothalamic cyst with or without LSV, or isolated LSV were found. All newborns are developing normally at a mean follow-up age of 33.3 months (+/- 19.6 moths). In group B, all four patients requested for termination of pregnancy.

CONCLUSION

Fetal CMV infection may cause focal GM changes, frequently accompanied by LSV, late in pregnancy. These changes may be isolated, or as part of a more generalized brain damage. When isolated, favorable prognosis is expected.