Neuroimaging of the Preterm Brain: Review and Recommendations

Neuroprognostication in neonatal encephalopathy due to presumed hypoxic-ischemic encephalopathy

Over the last two decades, significant progress has been made in the management of neonatal encephalopathy due to presumed hypoxic-ischemic encephalopathy. One key area that requires improvement is timely and accurate neuroprognostication in this population to identify infants who may benefit from early interventions and harness the maximum neuroplastic capacity of the developing brain. Improved neuroprognostication also has the potential to foster more effective communication of findings to caregivers. In this review, we explore whether improved neuroprognostication is possible by assessing clinical, biochemical, electrographic, neurophysiological, and neuroimaging biomarkers and their role in neuroprognostication. IMPACT STATEMENT: Over the last two decades, significant progress has been made in the management of neonatal encephalopathy due to presumed hypoxic-ischemic encephalopathy. One key area that requires improvement is timely and accurate neuroprognostication in this population to identify infants who may benefit from early interventions and harness the maximum neuroplastic capacity of the developing brain. In this review article, we discuss general concepts and principles of neuroprognostication and the role of each prognostic marker.

Prenatal inflammation exacerbates hyperoxia-induced neonatal brain injury

BACKGROUND

Premature born infants are at high risk to develop white matter injury (WMI). Hyperoxia and perinatal inflammation are main risk factors for preterm birth and associated brain injury. To date the majority of experimental studies have focused on isolated insults. However, clinically, WMI injury is a multifactorial disorder caused by a variety of triggers. To establish a clinically relevant rodent model of WMI, we combined prenatal inflammation with postnatal hyperoxia to investigate individual, and additive or synergistic effects on inflammatory processes, myelination and grey matter development.

METHODS

At embryonic day 20, pregnant Wistar rat dams received either a single intraperitoneal injection of 100 µg/ kg lipopolysaccharide (LPS) or sodium chloride. Offspring were either exposed to hyperoxia (80% O2) or normoxia (21% O2) from postnatal day 3 to 5. Animals were sacrificed immediately after hyperoxia or 6 days later, corresponding to term-equivalent age. White and grey matter development and neuroinflammatory responses were investigated at cellular and molecular levels applying immunohistochemistry, western blotting, real time PCR in brain tissues and multiplex protein expression analysis on serum samples.

RESULTS

Prenatal inflammation combined with postnatal hyperoxia resulted in reduced body weight and length in the offspring, accompanied by increased serum leptin levels at term equivalent age. The altered body parameters, like body weight, were associated with decreased brain volume, thinning of deep cortical layers and hypomyelination. As potential underlying mechanisms, we identified severe myelination deficits and an increased microglia activation associated with elevated inflammatory cytokine expression in brain tissues, while peripheral cytokine levels were reduced. Interestingly, effects on body size were mainly mediated by prenatal LPS, independent of hyperoxia, while oligodendrocyte degeneration was mainly induced by postnatal hyperoxia, independent of prenatal inflammation. However, for the majority of pathological changes, including brain size, myelination deficits, microglia activation and inflammatory cytokine expression, additive or synergistic effects were detected.

CONCLUSION

Prenatal inflammation combined with postnatal hyperoxia results in aggravated myelination deficits and inflammatory responses compared to single insults, making it an ideal model to improve our understanding of the complex pathophysiology underlying WMI and to evaluate urgently needed therapies.

The relationship between early life EEG and brain MRI in preterm infants: A systematic review

OBJECTIVE

To systematically review the literature on the associations between electroencephalogram (EEG) and brain magnetic resonance imaging (MRI) measures in preterm infants (gestational age < 37 weeks).

METHODS

A comprehensive search was performed in PubMed and EMBASE databases up to February 12th, 2024. Non-relevant studies were eliminated following the PRISMA guidelines.

RESULTS

Ten out of 991 identified studies were included. Brain MRI metrics used in these studies include volumes, cortical features, microstructural integrity, visual assessments, and cerebral linear measurements. EEG parameters were classified as qualitative (Burdjalov maturity score, seizure burden, and background activity) or quantitative (discontinuity, spectral content, amplitude, and connectivity). Among them, discontinuity and the Burdjalov score were most frequently examined. Higher discontinuity was associated with reduced brain volume, cortical surface, microstructural integrity, and linear measurements. The Burdjalov score related to brain maturation qualitatively assessed on MRI. No other consistent correlations could be established due to the variability across studies.

CONCLUSIONS

The reviewed studies utilized a variety of EEG and MRI measurements, while discontinuity and the Burdjalov score stood out as significant indicators of structural brain development.

SIGNIFICANCE

This review, for the first time, provides an extensive overview of EEG-MRI associations in preterm infants, potentially facilitating their clinical application.

Occurrence and Time of Onset of Intraventricular Hemorrhage in Preterm Neonates: A Systematic Review and Meta-Analysis of Individual Patient Data

Importance

Intraventricular hemorrhage (IVH) has been described to typically occur during the early hours of life (HOL); however, the exact time of onset is still unknown.

Objective

To investigate the temporal distribution of IVH reported in very preterm neonates.

Data Sources

PubMed, Embase, Cochrane Library, and Web of Science were searched on May 9, 2024.

Study Selection

Articles were selected in which at least 2 cranial ultrasonographic examinations were performed in the first week of life to diagnose IVH. Studies with only outborn preterm neonates were excluded.

Data Extraction And Synthesis

Data were extracted independently by 3 reviewers. A random-effects model was applied. This study is reported following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. The Quality in Prognostic Studies 2 tool was used to assess the risk of bias.

Main Outcomes And Measures

The overall occurrence of any grade IVH and severe IVH among preterm infants was calculated along with a 95% CI. The temporal distribution of the onset of IVH was analyzed by pooling the time windows 0 to 6, 0 to 12, 0 to 24, 0 to 48, and 0 to 72 HOL. A subgroup analysis was conducted using studies published before and after 2007 to allow comparison with the results of a previous meta-analysis.

Results

A total of 21 567 records were identified, of which 64 studies and data from 9633 preterm infants were eligible. The overall rate of IVH did not decrease significantly before vs after 2007 (36%; 95% CI, 30%-42% vs 31%; 95% CI, 25%-36%), nor did severe IVH (10%; 95% CI, 7%-13% vs 11%; 95% CI, 8%-14%). The proportion of very early IVH (up to 6 HOL) after 2007 was 9% (95% CI, 3%-23%), which was 4 times lower than before 2007 (35%; 95% CI, 24%-48%). IVH up to 24 HOL before and after 2007 was 44% (95% CI, 31%-58%) and 25% (95% CI, 15%-39%) and up to 48 HOL was 82% (95% CI, 65%-92%) and 50% (95% CI, 34%-66%), respectively.

Conclusion And Relevance

This systematic review and meta-analysis found that the overall prevalence of IVH in preterm infants has not changed significantly since 2007, but studies after 2007 showed a later onset as compared with earlier studies, with only a small proportion of IVHs occurring before 6 HOL.

Diagnostic accuracy of early neonatal MRI in predicting adverse motor outcomes in children born preterm: Systematic review and meta-analysis

AIM

To examine the diagnostic accuracy of Early structural and diffusion-weighted magnetic resonance imaging (MRI) (acquired at < 36 weeks postmenstrual age) to detect cerebral palsy (CP) or other adverse motor outcomes at or beyond 3 years corrected age in infants born preterm.

METHOD

In this systematic review and meta-analysis, we searched the CINAHL, Embase, PubMed, and Web of Science databases for studies without language restrictions and a prospectively registered protocol up to October 2023. We extracted the study details, associations presented, and meta-analyses conducted with pooled sensitivity and specificity.

RESULTS

Twenty-seven articles met the overall inclusion criteria. White matter injury, cerebellar haemorrhage, intraventricular haemorrhage, and lower thalamic volume were associated with poorer motor outcomes. Abnormal Early structural MRI detected infants with a later diagnosis of CP (n = 448, eight studies) with a pooled sensitivity of 98% (95% confidence interval [CI] = 86-100), specificity of 75% (95% CI = 51-93), and adverse motor outcomes (n = 215, four studies), with a pooled sensitivity of 39% (95% CI = 20-59) and a specificity of 90% (95% CI = 88-94).

INTERPRETATION

Early abnormal structural MRI predicted later CP with high sensitivity and specificity, while specificity was higher than sensitivity in predicting adverse motor outcomes using the Movement Assessment Battery for Children, Second Edition. Further research into diagnostic accuracy and association between Early MRI and long-term motor outcomes is warranted.

Feasibility and safety of autologous cord blood derived cell administration in extremely preterm infants: a single-centre, open-label, single-arm, phase I trial (CORD-SaFe study)

BACKGROUND

Evidence from preclinical studies in small and large animal models has shown neuroprotective effects of intravenous administration of umbilical cord blood derived cells (UCBCs). This study aimed to evaluate the feasibility of umbilical cord blood (UCB) collection, extraction of UCBCs, and subsequent safety of intravenous autologous administration of UCBCs in extremely preterm infants (born <28 weeks gestation).

METHODS

A single-centre, open-label, single-arm, safety and feasibility clinical intervention trial was conducted at Monash Medical Centre and Monash Children's Hospital, Melbourne, Australia. Participants were extremely preterm infants born at less than 28 weeks completed gestation, and exclusions included major congenital malformation, maternal blood-borne virus infection, and severe brain injury on postnatal cranial ultrasound. UCB was collected at birth, and UCBCs were characterised (total nucleated cell count (TNC), mononuclear cell count (MNC), CD34+ cell count) and cryopreserved. Infants were reinfused with autologous UCBCs (25-50 million MNCs/kg) intravenously in the second postnatal week. Primary outcomes included feasibility: sufficient UCB volume (>7 mL) and UCBC numbers following processing (>25 × 106 TNCs/kg); and safety: absence of adverse events directly related to UCBC administration.

FINDINGS

Forty-four UCB collections were attempted and sufficient UCB volume/UCBC extraction was demonstrated in 37 (84.1%) infants. Good Manufacturing Practice (GMP) grade cells were obtained in 31/44 (70.4%) of infants. Median (IQR) TNCs and MNCs collected were 130 (67-207) x 106/kg and 60 (39-105) x 106/kg, respectively. 23 infants with median (IQR) gestation of 26 (24-27) weeks and birth weight of 761 (650-946) grams were administered cells at a median (IQR) dose of 42.3 (31.1-62.3) x 106 MNCs/kg). No serious adverse events were noted, and the infusions were well-tolerated.

INTERPRETATION

This phase-1 clinical trial has shown UCBC collection and reinfusion was feasible in approximately 70% of extremely preterm infants and was well tolerated without any serious adverse events.

FUNDING

Funding to support this study was obtained from National Health and Medical Research Council of Australia, Cerebral Palsy Alliance, National Stem Cell Foundation of Australia, and Lions Cord Blood Foundation.

Preterm Sex Differences in Neurodevelopment and Brain Development from Early Life to 8 Years of Age

OBJECTIVE

To examine sex differences in neurodevelopmental outcomes and brain development from early life to 8 years in males and females born preterm.

STUDY DESIGN

This was a prospective cohort study of infants born very preterm (24-32 weeks of gestation) and followed to 8 years with standardized measures of neurodevelopment. Brain magnetic resonance imaging scans were performed soon after birth, term-equivalent age, and 8 years. The relationship between sex, severe brain injury, early pain exposure, fractional anisotropy, and neurodevelopmental outcomes were assessed using multivariable generalized estimating equations.

RESULTS

Males (n = 78) and females (n = 66) were similar in clinical risk factors. Male sex was associated with lower cognitive scores (β = -3.8, P = .02) and greater motor impairment (OR, 1.8; P = .04) across time. Male sex was associated with lower superior white matter fractional anisotropy across time (β = -0.01; P = .04). Sex moderated the association between severe brain injury, early pain, and neurodevelopmental outcomes. With severe brain injury, males had lower cognitive scores at 3 years of age (P < .001). With increasing pain, females had lower cognitive scores at 8 years of age (P = .008), and males had greater motor impairment at 4.5 years of age (P = .001) and 8 years of age (P = .05).

CONCLUSIONS

Males born preterm had lower cognitive scores and greater motor impairment compared with females, which may relate to differences in white matter maturation. The association between severe brain injury, early pain exposure, and neurodevelopmental outcomes was moderated by sex, indicating a differential response to early-life adversity in males and females born preterm.

Cerebral Ultrasound at Term-Equivalent Age: Correlations with Neuro-Motor Outcomes at 12-24 Months Corrected Age

Background/Objectives: Our research aimed to assess if correlations could be found between items evaluated at the cerebral ultrasound performed at term-equivalent age (TEA) and neuro-motor outcomes evaluated at 12 and 24 months of corrected age in a group of preterm infants. Methods: The following were assessed: the Levine Index, the diagonals of the lateral ventricles, the size of the ventricular midbody, the sinocortical distance, the width of the basal ganglia, the cortical depth at the level of the cingular sulcus and the maturation of the gyral folding. The neurologic evaluation was performed at 12 and 24 months of corrected age, according to the Amiel Tison neurologic examination, and the items from the calendar of motor acquisitions were used as outcome measures of the study-gross and fine motor subsets. The comparisons between the different groups were performed using the FANOVA test, with a statistically significant association for a p < 0.05. Results: The abnormal gross motor acquisitions at 12 months were significantly associated with an increased size of the ventricular midbody (p < 0.009) and a significantly decreased diameter of the basal ganglia (p < 0.011) on the TEA cerebral ultrasound. At 24 months, a significant association was found with increased size of the ventricular midbody (>10.33 mm) (p < 0.001), a decreased diameter of the basal ganglia (<12.9 mm) (p < 0.016), a decreased cortical depth (p < 0.021) and an immature gyral maturation pattern (p < 0.001). In the case of severely abnormal fine motor outcomes, at 12 months, there were statistically significant associations with an increased size of the ventricular midbody (p < 0.001) and an immature gyral folding pattern (p < 0.0180); at 24 months, significant associations were noted with the size of ventricular midbody (p < 0.001), a decreased diameter of the basal ganglia (p < 0.016), a decreased cortical depth (p < 0.021) and an immature gyration folding (p < 0.001). Conclusions: The abnormal gross and fine motor outcome in former premature infants at 12-24 months corrected age is significantly associated with abnormal findings in the head ultrasound examination performed at TEA reflecting both white matter (increased midbody distance) and grey matter (decreased diameter of the basal ganglia, decreased cortical depth and an immature gyration pattern) involvement.

Diagnostic accuracy of neonatal structural MRI scores to predict 6-year motor outcomes of children born very preterm

AIMS

This study aimed to (1) evaluate associations between Early and Term structural MRI (sMRI) brain abnormality scores and adverse motor outcomes at 6-years corrected age (CA), (2) determine their diagnostic accuracy in predicting adverse motor outcomes and cerebral palsy (CP) at 6-years CA.

METHODS

Infants born < 31-weeks gestational age (GA) returning for 6-year follow-up were included. Early and Term sMRI were scored using a validated method, deriving white matter, cortical grey matter, deep grey matter, cerebellar and global brain abnormality scores (GBAS). At 6-years CA, Movement Assessment Battery for Children-2nd Edition (MABC-2) was administered. Linear regression assessed associations between Early and Term GBAS/subscale scores and 6-year MABC-2 total score. For diagnostic accuracy, sMRI scores were categorised as none/mild vs moderate/severe, MABC-2 cut-off ≤ 5th percentile, and CP as present/absent.

RESULTS

Infants had Early MRI (n = 123) at mean PMA 32.5-weeks (median GA 28.4-weeks; mean birthweight 1101 g) and n = 114 had Term MRI (Mean PMA 40.8-weeks). Nine had CP and n = 116 had MABC-2 scores. Early (B: -1.92; p ≤ 0.001) and Term (B: -1.67; p ≤ 0.01) GBAS were negatively associated with MABC-2 scores. Both Early and Term GBAS had high specificity (Sp) and low sensitivity (Se) in predicting MABC-2 ≤ 5th percentile (Early: Se 36 %, Sp 82 %; Term: Se 28 %, Sp 93 %) and predicted CP with high Se and Sp (Early: Se 78 %, Sp 78 %; Term: Se 75 %, Sp 89 %).

CONCLUSION

High Sp of Early and Term MRI predicting an outcome on MABC-2 may help accurately identify infants unlikely to develop motor impairments at 6-years CA.

Early detection of cerebral sinus venous thrombosis in an extremely low birth weight infant using cranial ultrasound-case report and literature review

INTRODUCTION

Cerebral sinus venous thrombosis (CSVT) is a serious condition in premature infants. Early diagnosis is crucial, as untreated CSVT can progress to severe complications such as delayed-onset intraventricular hemorrhage (IVH), which could lead to poor outcomes in this population.

RESEARCH QUESTION

This case highlights that serial cranial ultrasound can detect CSVT early, enabling prompt treatment and preventing subsequent complications.

METHODS AND MATERIALS

We present the case of an extremely low birth weight infant diagnosed with CSVT based on cranial ultrasonography findings. The patient had no clinical symptoms or previously detected brain injury.

RESULTS

Anticoagulant therapy was initiated immediately after diagnosis. Clot resolution was observed on cranial ultrasound after 5 days and confirmed by magnetic resonance imaging (MRI) on the 82 day of life (36 + 4 weeks of gestational age).

CONCLUSION

This case shows the significant value of cranial ultrasound as a diagnostic tool in premature infants when MRI is not immediately available. Early detection and treatment using ultrasound may help prevent severe complications.

Brain age prediction and deviations from normative trajectories in the neonatal connectome

Structural and functional connectomes undergo rapid changes during the third trimester and the first month of postnatal life. Despite progress, our understanding of the developmental trajectories of the connectome in the perinatal period remains incomplete. Brain age prediction uses machine learning to estimate the brain's maturity relative to normative data. The difference between the individual's predicted and chronological age-or brain age gap (BAG)-represents the deviation from these normative trajectories. Here, we assess brain age prediction and BAGs using structural and functional connectomes for infants in the first month of life. We use resting-state fMRI and DTI data from 611 infants (174 preterm; 437 term) from the Developing Human Connectome Project (dHCP) and connectome-based predictive modeling to predict postmenstrual age (PMA). Structural and functional connectomes accurately predict PMA for term and preterm infants. Predicted ages from each modality are correlated. At the network level, nearly all canonical brain networks-even putatively later developing ones-generate accurate PMA prediction. Additionally, BAGs are associated with perinatal exposures and toddler behavioral outcomes. Overall, our results underscore the importance of normative modeling and deviations from these models during the perinatal period.

Altered functional connectivity in preterm neonates with intraventricular hemorrhage assessed using functional near-infrared spectroscopy

Intraventricular hemorrhage (IVH) is a common neurological injury following very preterm birth. Resting-state functional connectivity (RSFC) using functional magnetic resonance imaging (fMRI) is associated with injury severity; yet, fMRI is impractical for use in intensive care settings. Functional near-infrared spectroscopy (fNIRS) measures RSFC through cerebral hemodynamics and has greater bedside accessibility than fMRI. We evaluated RSFC in preterm neonates with IVH using fNIRS and fMRI at term-equivalent age, and compared fNIRS connectivity between healthy newborns and those with IVH. Sixteen very preterm born neonates were scanned with fMRI and fNIRS. Additionally, fifteen healthy newborns were scanned with fNIRS. In preterms with IVH, fNIRS and fMRI connectivity maps were compared using Euclidean and Jaccard distances. The severity of IVH in relation to fNIRS-RSFC strength was examined using generalized linear models. fNIRS and fMRI RSFC maps showed good correspondence. Connectivity strength was significantly lower in healthy newborns (p-value = 0.023) and preterm infants with mild IVH (p-value = 0.026) compared to infants with moderate/severe IVH. fNIRS has potential to be a new bedside tool for assessing brain injury and monitoring cerebral hemodynamics, as well as a promising biomarker for IVH severity in very preterm born infants.

Minimum effective dose of clemastine in a mouse model of preterm white matter injury

BACKGROUND

Preterm white matter injury (PWMI) is the most common cause of brain injury in premature neonates. PWMI involves a differentiation arrest of oligodendrocytes, the myelinating cells of the central nervous system. Clemastine was previously shown to induce oligodendrocyte differentiation and myelination in mouse models of PWMI at a dose of 10 mg/kg/day. The minimum effective dose (MED) of clemastine is unknown. Identification of the MED is essential for maximizing safety and efficacy in neonatal clinical trials. We hypothesized that the MED in neonatal mice is lower than 10 mg/kg/day.

METHODS

Mouse pups were exposed to normoxia or hypoxia (10% FiO2) from postnatal day 3 (P3) through P10. Vehicle or clemastine at one of four doses (0.5, 2, 7.5 or 10 mg/kg/day) was given to hypoxia-exposed pups. Myelination was assessed at age P14 and 10 weeks to determine the MED. Clemastine pharmacokinetics were evaluated at steady-state on day 8 of treatment.

RESULTS

Clemastine rescued hypoxia-induced hypomyelination with a MED of 7.5 mg/kg/day. Pharmacokinetic analysis of the MED revealed Cmax 44.0 ng/mL, t1/2 4.6 h, and AUC24 280.1 ng*hr/mL.

CONCLUSIONS

Based on these results, myelination-promoting exposures should be achievable with oral doses of clemastine in neonates with PWMI.

IMPACT

Preterm white matter injury (PWMI) is the most common cause of brain injury and cerebral palsy in premature neonates. Clemastine, an FDA-approved antihistamine, was recently identified to strongly promote myelination in a mouse model of PWMI and is a possible treatment. The minimum effective dose in neonatal rodents is unknown and is critical for guiding dose selection and balancing efficacy with toxicity in future clinical trials. We identified the minimum effective dose of clemastine and the associated pharmacokinetics in a murine chronic hypoxia model of PWMI, paving the way for a future clinical trial in human neonates.

A Simple MRI Score Predicts Pathological General Movements in Very Preterm Infants with Brain Injury-Retrospective Cohort Study

BACKGROUND/OBJECTIVES

Very preterm infants are at increased risk of brain injury and impaired brain development. The Total Abnormality Score and biometric parameters, such as biparietal width, interhemispheric distance and transcerebellar diameter, are simple measures to evaluate brain injury, development and growth using cerebral magnetic resonance imaging data at term-equivalent age. The aim of this study was to evaluate the association between the Total Abnormality Score and biometric parameters with general movements in very preterm infants with brain injury.

METHODS

This single-center retrospective cohort study included 70 very preterm infants (≤32 weeks' gestation and/or <1500 g birth weight) born between January 2017 and June 2021 in a level-three neonatal intensive care unit with brain injury-identified using cerebral magnetic resonance imaging data at term-equivalent age. General movements analysis was carried out at corrected age of 8-16 weeks. Binary logistic regression and Spearman correlation were used to examine the associations between the Total Abnormality Score and biometric parameters with general movements.

RESULTS

There was a significant association between the Total Abnormality Score and the absence of fidgety movements [OR: 1.19, 95% CI = 1.38-1.03] as well as a significant association between the transcerebellar diameter and fidgety movements (Spearman ρ = -0.269, p < 0.05).

CONCLUSIONS

Among very preterm infants with brain injury, the Total Abnormality Score can be used to predict the absence of fidgety movements and may be an easily accessible tool for identifying high-risk very preterm infants and planning early interventions accordingly.

Electroencephalographic Patterns on Follow-Up Visits in Extremely Premature Infants With Periventricular Leukomalacia: An Observational Study

BACKGROUND

Periventricular leukomalacia (PVL) is a common brain injury in premature infants, and epilepsy remains a significant complication. One concerning electroencephalographic (EEG) pattern found is developmental and/or epileptic encephalopathy with spike-and-wave activation in sleep (DEE-SWAS). This pattern is associated with persistent neuropsychological and motor deficits, even without a diagnosis of epilepsy. The purpose of this study is to identify the relationships between various PVL grades and EEG patterns in this population on follow-up visits, especially the occurrence of DEE-SWAS pattern on EEG.

METHODS

This is a retrospective study of <36 weeks gestational age newborns who were followed in the neurodevelopmental clinic at Corewell Health East/Corewell Health Children's Hospital in Royal Oak, Michigan, between 2020 and 2022. Patients' demographics along with prematurity complications, diagnostic head ultrasound (HUS), and EEG studies were reviewed and graded. EEG studies are usually ordered when seizures were suspected.

RESULTS

A total of 155 newborns met the inclusion criteria. Twenty-six patients had PVL. Nine patients had grade 2 to 3 PVL based on HUS review. EEG was performed on 15 patients with PVL at a mean age of 22 months. More severe PVL grades were significantly associated with worse EEG patterns (P = 0.005). Five patients had DEE-SWAS pattern on EEG, all of whom had grade 2 or 3 PVL. Epilepsy was eventually diagnosed in three infants with PVL.

CONCLUSIONS

EEG can help identify important abnormal electrographic patterns in premature infants with PVL early in life; this might give a window of opportunity to intervene early and improve long-term developmental outcomes in this population.

Point of care magnetic resonance neonatal neuroimaging applications and early imaging in infants under active therapeutic hypothermia: a perspective

As care of the most vulnerable infants in the neonatal intensive care unit (NICU) evolves, improved and real-time understanding of brain health becomes key. The availability of an in-NICU magnetic resonance imaging (MRI) scanner provides unique options to bedside care providers and researchers. We present our perspective on the 1-Tesla MRI unit in our NICU and its utilities and applications both in the clinical and research fields. We also discuss our experience with early and serial MRI in a cohort of infants with hypoxic-ischemic encephalopathy while undergoing therapeutic hypothermia, using a compatible cooling blanket and monitoring apparatus with special insight into the planning and organization between providers, and parental perspectives around early, detailed imaging.

Regional cerebral oxygen saturation variability and brain injury in preterm infants

Objective

To examine whether variation of regional cerebral oxygen saturation (rScO2) within three days after delivery predicts development of brain injury (intraventricular/cerebellar hemorrhage or white matter injury) in preterm infants.

Study design

A prospective study of neonates <32 weeks gestational age with normal cranial ultrasound admitted between 2018 and 2022. All received rScO2 monitoring with near-infrared spectroscopy at admission up to 72 h of life. To assess brain injury a magnetic resonance imaging was performed at term-equivalent age. We assessed the association between rScO2 variability (short-term average real variability, rScO2ARV, and standard deviation, rScO2SD), mean rScO2 (rScO2MEAN), and percentage of time rScO2 spent below 60% (rScO2TIME<60%) during the first 72 h of life and brain injury.

Results

The median [IQR] time from birth to brain imaging was 68 [59-79] days. Of 81 neonates, 49 had some form of brain injury. Compared to neonates without injury, in those with injury rScO2ARV was higher during the first 24 h (P = 0.026); rScO2SD was higher at 24 and 72 h (P = 0.029 and P = 0.030, respectively), rScO2MEAN was lower at 48 h (P = 0.042), and rScO2TIME<60% was longer at 24, 48, and 72 h (P = 0.050, P = 0.041, and P = 0.009, respectively). Similar results were observed in multivariable logistic regression. Although not all results were statistically significant, increased rScO2 variability (rScO2ARV and rScO2SD) and lower mean values of rScO2 were associated with increased likelihood of brain injury.

Conclusions

In preterm infants increased aberration of rScO2 in early postdelivery period was associated with an increased likelihood of brain injury diagnosis at term-equivalent age.

Transfontanellar shear wave elastography of the neonatal brain for quantitative evaluation of white matter damage

Cerebral white matter damage (WMD) is the most frequent brain lesion observed in infants surviving premature birth. Qualitative B-mode cranial ultrasound (cUS) is widely used to assess brain integrity at bedside. Its limitations include lower discriminatory power to predict long-term outcomes compared to magnetic resonance imaging (MRI). Shear wave elastography (SWE), a promising ultrasound imaging modality, might improve this limitation by detecting quantitative differences in tissue stiffness. The study enrolled 90 neonates (52% female, mean gestational age = 30.1  ± 4.5 weeks), including 78 preterm and 12 term controls. Preterm neonates underwent B-mode and SWE assessments in frontal white matter (WM), parietal WM, and thalami on day of life (DOL) 3, DOL8, DOL21, 40 weeks, and MRI at term equivalent age (TEA). Term infants were assessed on DOL3 only. Our data revealed that brain stiffness increased with gestational age in preterm infants but remained lower at TEA compared to the control group. In the frontal WM, elasticity values were lower in preterm infants with WMD detected on B-mode or MRI at TEA and show a good predictive value at DOL3. Thus, brain stiffness measurement using SWE could be a useful screening method for early identification of preterm infants at high WMD risk.Registration numbers: EudraCT number ID-RCB: 2012-A01530-43, ClinicalTrial.gov number NCT02042716.

Neuroimaging to guide neuroprognostication in the neonatal intensive care unit

PURPOSE OF REVIEW

Neurological problems are common in infants admitted to the neonatal intensive care unit (NICU). Various neuroimaging modalities are available for neonatal brain imaging and are selected based on presenting problem, timing and patient stability.

RECENT FINDINGS

Neuroimaging findings, taken together with clinical factors and serial neurological examination can be used to predict future neurodevelopmental outcomes. In this narrative review, we discuss neonatal neuroimaging modalities, and how these can be optimally utilized to assess infants in the NICU. We will review common patterns of brain injury and neurodevelopmental outcomes in hypoxic-ischemic encephalopathy, perinatal arterial ischemic stroke and preterm brain injury.

SUMMARY

Timely and accurate neuroprognostication can identify infants at risk for neurodevelopmental impairment and allow for early intervention and targeted therapies to improve outcomes.

Minimum Effective Dose of Clemastine in a Mouse Model of Preterm White Matter Injury

Background

Preterm white matter injury (PWMI) is the most common cause of brain injury in premature neonates. PWMI involves a differentiation arrest of oligodendrocytes, the myelinating cells of the central nervous system. Clemastine was previously shown to induce oligodendrocyte differentiation and myelination in mouse models of PWMI at a dose of 10 mg/kg/day. The minimum effective dose (MED) of clemastine is unknown. Identification if the MED is essential for maximizing safety and efficacy in neonatal clinical trials. We hypothesized that the MED in neonatal mice is lower than 10 mg/kg/day.

Methods

Mouse pups were exposed to normoxia or hypoxia (10% FiO 2 ) from postnatal day 3 (P3) through P10. Vehicle or clemastine fumarate at one of four doses (0.5, 2, 7.5 or 10 mg/kg/day) was given orally to hypoxia-exposed pups. At P14, myelination was assessed by immunohistochemistry and electron microscopy to determine the MED. Clemastine pharmacokinetics were evaluated at steady-state on day 8 of treatment.

Results

Clemastine rescued hypoxia-induced hypomyelination with a MED of 7.5 mg/kg/day. Pharmacokinetic analysis of the MED revealed C max 44.0 ng/mL, t 1/2 4.6 hours, and AUC 24 280.1 ng*hr/mL.

Conclusion

Based on these results, myelination-promoting exposures should be achievable with oral doses of clemastine in neonates with PWMI.

Key Points

Preterm white matter injury (PWMI) is the most common cause of brain injury and cerebral palsy in premature neonates.Clemastine, an FDA-approved antihistamine, was recently identified to strongly promote myelination in a mouse model of PWMI and is a possible treatment.The minimum effective dose in neonatal rodents is unknown and is critical for guiding dose selection and balancing efficacy with toxicity in future clinical trials.We identified the minimum effective dose of clemastine and the associated pharmacokinetics in a murine chronic hypoxia model of PWMI, paving the way for a future clinical trial in human neonates.

Key roles of glial cells in the encephalopathy of prematurity

Across the globe, approximately one in 10 babies are born preterm, that is, before 37 weeks of a typical 40 weeks of gestation. Up to 50% of preterm born infants develop brain injury, encephalopathy of prematurity (EoP), that substantially increases their risk for developing lifelong defects in motor skills and domains of learning, memory, emotional regulation, and cognition. We are still severely limited in our abilities to prevent or predict preterm birth. No longer just the "support cells," we now clearly understand that during development glia are key for building a healthy brain. Glial dysfunction is a hallmark of EoP, notably, microgliosis, astrogliosis, and oligodendrocyte injury. Our knowledge of glial biology during development is exponentially expanding but hasn't developed sufficiently for development of effective neuroregenerative therapies. This review summarizes the current state of knowledge for the roles of glia in infants with EoP and its animal models, and a description of known glial-cell interactions in the context of EoP, such as the roles for border-associated macrophages. The field of perinatal medicine is relatively small but has worked passionately to improve our understanding of the etiology of EoP coupled with detailed mechanistic studies of pre-clinical and human cohorts. A primary finding from this review is that expanding our collaborations with computational biologists, working together to understand the complexity of glial subtypes, glial maturation, and the impacts of EoP in the short and long term will be key to the design of therapies that improve outcomes.

White Matter Injury on Early-versus-Term-Equivalent Age Brain MRI in Infants Born Preterm

BACKGROUND AND PURPOSE

White matter injury in infants born preterm is associated with adverse neurodevelopmental outcomes, depending on the extent and location. White matter injury can be visualized with MR imaging in the initial weeks following preterm birth but is more commonly defined at term-equivalent-age MR imaging. Our aim was to see how white matter injury detection in MR imaging compares between the 2 time points.

MATERIALS AND METHODS

This study compared white matter injury on early brain MR imaging (30-34 weeks' postmenstrual age) with white matter injury assessment at term-equivalent (37-42 weeks) MR imaging, using 2 previously published and standardized scoring systems, in a cohort of 30 preterm infants born at <33 weeks' gestational age.

RESULTS

There was a strong association between the systematic assessments of white matter injury at the 2 time points (P = .007) and the global injury severity (P < .001).

CONCLUSIONS

Although the optimal timing to undertake neuroimaging in the preterm infant remains to be determined, both early (30-34 weeks) and term-equivalent MR imaging provide valuable information on white matter injury and the risk of associated sequelae.

Correlations between Head Ultrasounds Performed at Term-Equivalent Age in Premature Neonates and General Movements Neurologic Examination Patterns

BACKGROUND AND AIM

Our research aims to find correlations between the brain imaging performed at term-corrected age and the atypical general movement (GM) patterns noticed during the same visit a-cramped-synchronized (CS) or poor repertoire (PR)-in formerly premature neonates to provide evidence for the structures involved in the modulation of GM patterns that could be injured and result in the appearance of these patterns and further deficits.

MATERIALS AND METHODS

A total of 44 preterm neonates ((mean GA, 33.59 weeks (+2.43 weeks)) were examined in the follow-up program at Life Memorial Hospital Bucharest at term-equivalent age (TEA). The GM and ultrasound examinations were performed by trained and certified specialists. Three GM pattens were noted (normal, PR, or CS), and the measurements of the following cerebral structures were conducted via head ultrasounds: ventricular index, the short and long axes of the lateral ventricles, the midbody distance of the lateral ventricle, the diagonal of the caudate nucleus, the width of the basal ganglia, the width of the interhemispheric fissure, the sinocortical width, the length and thickness of the callosal body, the anteroposterior diameter of the pons, the diameter of the vermis, and the transverse diameters of the cerebellum and vermis. The ultrasound measurements were compared between the groups in order to find statistically significant correlations by using the FANOVA test (significance p < 0.05).

RESULTS

The presence of the CS movement pattern was significantly associated with an increased ventricular index (mean 11.36 vs. 8.90; p = 0.032), increased midbody distance of the lateral ventricle-CS versus PR (8.31 vs. 3.73; p = 0.001); CS versus normal (8.31 vs. 3.34; p = 0.001), increased long and short axes of the lateral ventricles (p < 0.001), and decreased width of the basal ganglia-CS versus PR (11.07 vs. 15.69; p = 0.001); CS versus normal pattern (11.07 vs. 15.15; p = 0.0010). The PR movement pattern was significantly associated with an increased value of the sinocortical width when compared to the CS pattern (p < 0.001) and a decreased anteroposterior diameter of the pons when compared to both the CS (12.06 vs. 16.83; p = 0.001) and normal (12.06 vs. 16.78; p = 0.001) patterns. The same correlations were present when the subgroup of infants with a GA ≤ 32 weeks was analyzed.

CONCLUSIONS

Our study demonstrated that there are correlations between atypical GM patterns (cramped-synchronized-CS and poor repertoire-PR) and abnormalities in the dimensions of the structures measured via ultrasound at the term-equivalent age. The correlations could provide information about the structures that are affected and could lead to a lack of modulation in the GM patterns.

Major Surgery, Brain Injury, and Neurodevelopmental Outcomes in Very Preterm Infants

OBJECTIVES

We determined whether (1) major surgery is associated with an increased risk for brain injury and adverse neurodevelopment and (2) brain injury modifies associations between major surgery and neurodevelopment in very preterm infants.

METHODS

Prospectively enrolled infants across 3 tertiary neonatal intensive care units underwent early-life and/or term-equivalent age MRI to detect moderate-severe brain injury. Eighteen-month neurodevelopmental outcomes were assessed with Bayley Scales of Infant and Toddler Development, third edition. Multivariable logistic and linear regressions were used to determine associations of major surgery with brain injury and neurodevelopment, adjusting for clinical confounders.

RESULTS

There were 294 infants in this study. Major surgery was associated with brain injury (odds ratio 2.54, 95% CI 1.12-5.75, p = 0.03) and poorer motor outcomes (β = -7.92, 95% CI -12.21 to -3.64, p < 0.001), adjusting for clinical confounders. Brain injury x major surgery interaction significantly predicted motor scores (p = 0.04): Lowest motor scores were in infants who required major surgery and had brain injury.

DISCUSSION

There is an increased risk for brain injury and adverse motor outcomes in very preterm infants who require major surgery, which may be a marker of clinical illness severity. Routine brain MRI to detect brain injury and close neurodevelopmental surveillance should be considered in this subgroup of infants.

Neurodevelopmental Correlates of Brain Magnetic Resonance Imaging Abnormalities in Extremely Low-birth-weight Infants

OBJECTIVE

To evaluate the relationship between impaired brain growth and structural brain abnormalities at term-equivalent age (TEA) and neurodevelopment in extremely low-birth-weight (ELBW) infants over the first 2 years.

METHODS

ELBW infants born from 2009 through 2018 and undergoing brain magnetic resonance imaging (MRI) at TEA were enrolled in this retrospective cohort study. MRI scans were reviewed using a validated quali-quantitative score, including several white and gray matter items. Neurodevelopment was assessed at 6, 12, 18, and 24 months using the Griffiths scales. The independent associations between MRI subscores and the trajectories of general and specific neurodevelopmental functions were analyzed by generalized estimating equations.

RESULTS

One hundred-nine ELBW infants were included. White matter volume reduction and delayed myelination were associated with worse general development (b = -2.33, P = .040; b = -6.88, P = .049 respectively), social skills (b = -3.13, P = .019; b = -4.79, P = .049), and eye-hand coordination (b = -3.48, P = .009; b = -7.21, P = .045). Cystic white matter lesions were associated with poorer motor outcomes (b = -4.99, P = .027), while white matter signal abnormalities and corpus callosum thinning were associated with worse nonverbal cognitive performances (b = -6.42, P = .010; b = -6.72, P = .021, respectively). Deep gray matter volume reduction correlated with worse developmental trajectories.

CONCLUSIONS

Distinctive MRI abnormalities correlate with specific later developmental skills. This finding may suggest that TEA brain MRI may assist with neurodevelopmental prediction, counseling of families, and development of targeted supportive interventions to improve neurodevelopment in ELBW neonates.

Magnetic Resonance Imaging-Based Distribution and Reversibility of Lesions in Pediatric Vigabatrin-Related Brain Toxicity

BACKGROUND

We aimed to systematically characterize the magnetic resonance imaging (MRI) findings in vigabatrin-related neurotoxicity in children and determine the reversibility of lesions based on follow-up images.

METHODS

We evaluated children with a history of refractory seizures who had a brain MRI while on vigabatrin therapy. We included available brain MRI studies before vigabatrin therapy initiation, during vigabatrin treatment, and after vigabatrin was discontinued. A pediatric neuroradiologist systematically assessed images on T2/fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted imaging /apparent diffusion coefficient sequences to identify hyperintense lesions and/or restricted diffusion. The frequency of abnormal signal at each location was determined, as well as the reversibility of these after vigabatrin discontinuation.

RESULTS

MRIs of 43 patients were reviewed: 13 before vigabatrin initiation, 18 during treatment, and 12 after vigabatrin discontinuation. In the MRIs acquired during vigabatrin treatment, most lesions on T2/FLAIR occurred in the globus pallidi, thalami, and midbrain. Correspondingly, the most common locations for restricted diffusion were the globus pallidi, thalami, and subthalamic nuclei. On MRI after vigabatrin discontinuation, complete resolution of lesions on T2/FLAIR in all patients was seen in the midbrain, dentate nuclei, subthalamic nuclei, and hypothalami. Complete resolution of restricted diffusion was observed in the globus pallidi, midbrain, dentate nuclei, hippocampi, anterior commissure, and hypothalami.

CONCLUSION

Globus pallidi and thalami are the most commonly affected structures in vigabatrin-related toxicity, and most vigabatrin-related neuroimaging findings are reversible.

Development of neonatal-specific sequences for portable ultralow field magnetic resonance brain imaging: a prospective, single-centre, cohort study

Background

Magnetic Resonance (MR) imaging is key for investigation of suspected newborn brain abnormalities. Access is limited in low-resource settings and challenging in infants needing intensive care. Portable ultralow field (ULF) MRI is showing promise in bedside adult brain imaging. Use in infants and children has been limited as brain-tissue composition differences necessitate sequence modification. The aim of this study was to develop neonatal-specific ULF structural sequences and test these across a range of gestational maturities and pathologies to inform future validation studies.

Methods

Prospective cohort study within a UK neonatal specialist referral centre. Infants undergoing 3T MRI were recruited for paired ULF (64mT) portable MRI by convenience sampling from the neonatal unit and post-natal ward. Key inclusion criteria: 1) Infants with risk or suspicion of brain abnormality, or 2) preterm and term infants without suspicion of major genetic, chromosomal or neurological abnormality. Exclusions: presence of contra-indication for MR scanning. ULF sequence parameters were optimised for neonatal brain-tissues by iterative and explorative design. Neuroanatomic and pathologic features were compared by unblinded review, informing optimisation of subsequent sequence generations in a step-wise manner. Main outcome: visual identification of healthy and abnormal brain tissues/structures. ULF MR spectroscopy, diffusion, susceptibility weighted imaging, arteriography, and venography require pre-clinical technical development and have not been tested.

Findings

Between September 23, 2021 and October 25, 2022, 102 paired scans were acquired in 87 infants; 1.17 paired scans per infant. Median age 9 days, median postmenstrual age 40+2 weeks (range: 31+3-53+4). Infants had a range of intensive care requirements. No adverse events observed. Optimised ULF sequences can visualise key neuroanatomy and brain abnormalities. In finalised neonatal sequences: T2w imaging distinguished grey and white matter (7/7 infants), ventricles (7/7), pituitary tissue (5/7), corpus callosum (7/7) and optic nerves (7/7). Signal congruence was seen within the posterior limb of the internal capsule in 10/11 infants on finalised T1w scans. In addition, brain abnormalities visualised on ULF optimised sequences have similar MR signal patterns to 3T imaging, including injury secondary to infarction (6/6 infants on T2w scans), hypoxia-ischaemia (abnormal signal in basal ganglia, thalami and white matter 2/2 infants on T2w scans, cortical highlighting 1/1 infant on T1w scan), and congenital malformations: polymicrogyria 3/3, absent corpus callosum 2/2, and vermian hypoplasia 3/3 infants on T2w scans. Sequences are susceptible to motion corruption, noise, and ULF artefact. Non-identified pathologies were small or subtle.

Interpretation

On unblinded review, optimised portable MR can provide sufficient contrast, signal, and resolution for neuroanatomical identification and detection of a range of clinically important abnormalities. Blinded validation studies are now warranted.

Funding

The Bill and Melinda Gates Foundation, the MRC, the Wellcome/EPSRC Centre for Medical Engineering, the MRC Centre for Neurodevelopmental Disorders, and the National Institute for Health Research (NIHR) Biomedical Research Centres based at Guy's and St Thomas' and South London & Maudsley NHS Foundation Trusts and King's College London.

Novel metrics to characterize temporal lobe of very preterm infants on term-equivalent brain MRI

BACKGROUND

Preterm birth adversely impacts brain development and contributes to neurodevelopmental impairment; the temporal lobe may be particularly vulnerable to the impact of very preterm (VP) birth. Yet, no prior magnetic resonance imaging (MRI) scoring system incorporated a method to quantify temporal lobe size in VP infants.

METHODS

We developed and applied three metrics (temporal lobe length, extra-axial space, and temporal horn width) to quantify temporal lobe structure on term-equivalent brain MRIs obtained from 74 VP and 16 term infants. We compared metrics between VP and term infants and explored associations of each metric with perinatal risk factors.

RESULTS

All metrics had excellent reliability (intra-class correlation coefficient 0.62-0.98). VP infants had lower mean temporal lobe length (76.8 mm versus 79.2 mm, p = 0.02); however, the difference attenuated after correction for postmenstrual age. VP infants had larger temporal horn widths compared with term infants (2.6 mm versus 1.8 mm, p < 0.001). Temporal lobe length was positively associated with gestational age, birth weight, and male sex, and negatively associated with the duration of parenteral nutrition.

CONCLUSIONS

The proposed metrics are reliable and sensitive in distinguishing differences in temporal lobe development between VP and full-term infants.

IMPACT

We developed a novel method for quantifying temporal lobe size among very preterm infants at term equivalent using simple metrics performed on brain MRI. Temporal lobe metrics were reliable, correlated with brain volume from volumetric analysis, and were sensitive in identifying differences in temporal lobe development among preterm compared with term infants, specifically larger temporal horn size in preterm infants. This temporal lobe metric system will enable future work to delineate the perinatal and postnatal factors that impact temporal lobe growth, and better understand the relationship between temporal lobe disturbance and neurodevelopment in very preterm infants.

Development and characterization of transfontanelle photoacoustic imaging system for detection of intracranial hemorrhages and measurement of brain oxygenation: Ex-vivo

We have developed and optimized an imaging system to study and improve the detection of brain hemorrhage and to quantify oxygenation. Since this system is intended to be used for brain imaging in neonates through the skull opening, i.e., fontanelle, we called it, Transfontanelle Photoacoustic Imaging (TFPAI) system. The system is optimized in terms of optical and acoustic designs, thermal safety, and mechanical stability. The lower limit of quantification of TFPAI to detect the location of hemorrhage and its size is evaluated using in-vitro and ex-vivo experiments. The capability of TFPAI in measuring the tissue oxygenation and detection of vasogenic edema due to brain blood barrier disruption are demonstrated. The results obtained from our experimental evaluations strongly suggest the potential utility of TFPAI, as a portable imaging modality in the neonatal intensive care unit. Confirmation of these findings in-vivo could facilitate the translation of this promising technology to the clinic.

Child Neurology: Cortical Malformations in Preterm Infants: Case From a Prospective Cohort

Malformations of cortical development (MCD) are a rare group of disorders with heterogeneous clinical, neuroimaging, and genetic features. MCD consist of disruptions in the development of the cerebral cortex secondary to genetic, metabolic, infectious, or vascular etiologies. MCD are typically classified by stage of disrupted cortical development as secondary to abnormal: (1) neuronal proliferation or apoptosis, (2) neuronal migration, or (3) postmigrational cortical development. MCD are typically detected with brain MRI when an infant or child becomes symptomatic, presenting with seizures, developmental delay, or cerebral palsy. With recent advances in neuroimaging, cortical malformations can be detected using ultrasound or MRI during the fetal period or in the neonatal period. Of interest, preterm infants are born at a time when many cortical developmental processes are still occurring. However, there is a paucity of literature describing the neonatal imaging findings, clinical presentation, and evolution over time of cortical malformations in preterm infants. In this study, we present the neuroimaging findings from early life to term-equivalent age and childhood neurodevelopmental outcomes of an infant born very preterm (<32 weeks' postmenstrual age) with MCD detected incidentally on neonatal research brain MRI. These brain MRIs were performed as part of a prospective longitudinal cohort study of 160 very preterm infants; MCD were detected incidentally in 2 infants.

Combining MRI and Spectral EEG for Assessment of Neurocognitive Outcomes in Preterm Infants

INTRODUCTION

Predicting impairment in preterm children is challenging. Our aim is to explore the association between MRI at term-equivalent age (TEA) and neurocognitive outcomes in late childhood and to assess whether the addition of EEG improves prognostication.

METHODS

This prospective observational study included forty infants with gestational age 24 + 0-30 + 6. Children were monitored with multichannel EEG for 72 h after birth. Total absolute band power for the delta band on day 2 was calculated. Brain MRI was performed at TEA and scored according to the Kidokoro scoring system. At 10-12 years of age, we evaluated neurocognitive outcomes with Wechsler Intelligence Scale for Children 4th edition, Vineland adaptive behavior scales 2nd edition and Behavior Rating Inventory of Executive Function. We performed linear regression analysis to examine the association between outcomes and MRI and EEG, respectively, and multiple regression analysis to explore the combination of MRI and EEG.

RESULTS

Forty infants were included. There was a significant association between global brain abnormality score and composite outcomes of WISC and Vineland test, but not the BRIEF test. The adjusted R2 was 0.16 and 0.08, respectively. For EEG, adjusted R2 was 0.34 and 0.15, respectively. When combining MRI and EEG data, adjusted R2 changed to 0.36 for WISC and 0.16 for the Vineland test.

CONCLUSION

There was a small association between TEA MRI and neurocognitive outcomes in late childhood. Adding EEG to the model improved the explained variance. Combining EEG and MRI data did not have any additional benefit over EEG alone.

Evaluation of a Cranial Ultrasound Screening Protocol for Very Preterm Infants

OBJECTIVES

Cranial ultrasound (cUS) screening is recommended for preterm neonates born before 32 weeks' gestational age (GA). The primary aim of this study was to determine if both a day 3 and day 8 cUS screening examination is necessary for all neonates.

METHODS

A retrospective observational study was performed at a tertiary-level Australian hospital. Frequencies of cranial ultrasound abnormality (CUA) were compared between routine screening performed at postnatal days 3, 8, and 42. Univariate and multivariate analyses of risk factors for intraventricular hemorrhage (IVH) was performed using logistic regression.

RESULTS

cUS examinations on 712 neonates born before 32 weeks' GA were included. Neonates were divided into 2 groups: 99 neonates in the 23-25 weeks 6 days GA (group A) and 613 neonates in the 26-31 weeks 6 days GA (group B). All CUA occurred more frequently in group A neonates and in the subset of group B neonates who had defined risk factors. Low-risk group B neonates had lower incidence of CUAs demonstrated on day 8 cUS than high-risk group B neonates, with no significant differences between day 3 and day 8. Logistic regression analysis identified a number of risk factors (vaginal delivery, small for GA, Apgar score <7 at 5 minutes, intubation, patent ductus arteriosus and infection) that were associated with increased frequency of IVH on day 8. In neonates born between 30 and 31 weeks 6 days GA, 35% had a CUA identified.

CONCLUSIONS

Low-risk preterm neonates born between 26 and 31 weeks 6 days GA, without complications, could be screened with a single early cUS examination around day 8 without missing substantial abnormality.

Three-dimensional cranial ultrasound and functional near-infrared spectroscopy for bedside monitoring of intraventricular hemorrhage in preterm neonates

Germinal Matrix-Intraventricular Hemorrhage (GMH-IVH) remains a significant cause of adverse neurodevelopment in preterm infants. Current management relies on 2-dimensional cranial ultrasound (2D cUS) ventricular measurements. Reliable biomarkers are needed to aid in the early detection of posthemorrhagic ventricular dilatation (PHVD) and subsequent neurodevelopment. In a prospective cohort study, we incorporated 3-dimensional (3D) cUS and functional near-infrared spectroscopy (fNIRS) to monitor neonates with GMH-IVH. Preterm neonates (≤ 32 weeks' gestation) were enrolled following a GMH-IVH diagnosis. Neonates underwent sequential measurements: 3D cUS images were manually segmented using in-house software, and the ventricle volumes (VV) were extracted. Multichannel fNIRS data were acquired using a high-density system, and spontaneous functional connectivity (sFC) was calculated. Of the 30 neonates enrolled in the study, 19 (63.3%) had grade I-II and 11 (36.7%) grade III-IV GMH-IVH; of these, 7 neonates (23%) underwent surgical interventions to divert cerebrospinal fluid (CSF). In infants with severe GMH-IVH, larger VV were significantly associated with decreased |sFC|. Our findings of increased VV and reduced sFC suggest that regional disruptions of ventricular size may impact the development of the underlying white matter. Hence, 3D cUS and fNIRS are promising bedside tools for monitoring the progression of GMH-IVH in preterm neonates.

Biomedical and Psychosocial Determinants of Early Neurodevelopment After Preterm Birth

Prematurity and them related conditions are subject of scientific discussion. From the point of view optimization of postpartum processes, timely assessment of individual biomedical and psychosocial conditions and management of preventive intervention is very important, because of its linkage to issues of preterm infants and their families in long-term perspectives. The goal of the literature review is to bring together existing body of knowledge on biomedical, psychological, and social issues of premature infants related to early neurodevelopment in order to achieve better systemic vision. For this goal scientific articles related to neurological development delay of premature children and the possibilities of their timely identification were processed using electronic scientific search systems. Diagnostic tools to identify at-risk children and early intervention programs discussed in the article, significantly improve the chances of premature child development. In the article Introduced materials are to support: Clinicians to make correct decisions regarding important components of premature infants; Healthcare policy makers to plan targeted programs and activities; Public to better understand prematurity issues, especially in case of prematurely-born family members.

A 1-Tesla MRI system for dedicated brain imaging in the neonatal intensive care unit

Objective

To assess the feasibility of a point-of-care 1-Tesla MRI for identification of intracranial pathologies within neonatal intensive care units (NICUs).

Methods

Clinical findings and point-of-care 1-Tesla MRI imaging findings of NICU patients (1/2021 to 6/2022) were evaluated and compared with other imaging modalities when available.

Results

A total of 60 infants had point-of-care 1-Tesla MRI; one scan was incompletely terminated due to motion. The average gestational age at scan time was 38.5 ± 2.3 weeks. Transcranial ultrasound (n = 46), 3-Tesla MRI (n = 3), or both (n = 4) were available for comparison in 53 (88%) infants. The most common indications for point-of-care 1-Tesla MRI were term corrected age scan for extremely preterm neonates (born at greater than 28 weeks gestation age, 42%), intraventricular hemorrhage (IVH) follow-up (33%), and suspected hypoxic injury (18%). The point-of-care 1-Tesla scan could identify ischemic lesions in two infants with suspected hypoxic injury, confirmed by follow-up 3-Tesla MRI. Using 3-Tesla MRI, two lesions were identified that were not visualized on point-of-care 1-Tesla scan: (1) punctate parenchymal injury versus microhemorrhage; and (2) small layering IVH in an incomplete point-of-care 1-Tesla MRI with only DWI/ADC series, but detectable on the follow-up 3-Tesla ADC series. However, point-of-care 1-Tesla MRI could identify parenchymal microhemorrhages, which were not visualized on ultrasound.

Conclusion

Although limited by field strength, pulse sequences, and patient weight (4.5 kg)/head circumference (38 cm) restrictions, the Embrace^® point-of-care 1-Tesla MRI can identify clinically relevant intracranial pathologies in infants within a NICU setting.

Cranial Ultrasound Abnormalities in Small for Gestational Age or Growth-Restricted Infants Born over 32 Weeks Gestation: A Systematic Review and Meta-Analysis

AIM

To perform a systematic review and meta-analysis of existing literature to evaluate the incidence of cranial ultrasound abnormalities (CUAs) amongst moderate to late preterm (MLPT) and term infants, affected by fetal growth restriction (FGR) or those classified as small for gestational age (SGA).

METHODS

A systematic review methodology was performed, and Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statement was utilised. Descriptive and observational studies reporting cranial ultrasound outcomes on FGR/SGA MLPT and term infants were included. Primary outcomes reported was incidence of CUAs in MLPT and term infants affected by FGR or SGA, with secondary outcomes including brain structure development and growth, and cerebral artery Dopplers. A random-effects model meta-analysis was performed. Risk of Bias was assessed using the Newcastle-Ottawa scale for case-control and cohort studies, and Joanna Briggs Institute Critical Appraisal Checklist for studies reporting prevalence data. GRADE was used to assess for certainty of evidence.

RESULTS

Out of a total of 2085 studies identified through the search, seventeen were deemed to be relevant and included. Nine studies assessed CUAs in MLPT FGR/SGA infants, seven studies assessed CUAs in late preterm and term FGR/SGA infants, and one study assessed CUAs in both MLPT and term FGR/SGA infants. The incidence of CUAs in MLPT, and late preterm to term FGR/SGA infants ranged from 0.4 to 33% and 0 to 70%, respectively. A meta-analysis of 7 studies involving 168,136 infants showed an increased risk of any CUA in FGR infants compared to appropriate for gestational age (AGA) infants (RR 1.96, [95% CI 1.26-3.04], I² = 68%). The certainty of evidence was very low due to non-randomised studies, methodological limitations, and heterogeneity. Another meta-analysis looking at 4 studies with 167,060 infants showed an increased risk of intraventricular haemorrhage in FGR/SGA infants compared to AGA infants (RR 2.40, [95% CI 2.03-2.84], I² = 0%). This was also of low certainty.

CONCLUSIONS

The incidence of CUAs in MLPT and term growth-restricted infants varied widely between studies. Findings from the meta-analyses suggest the risk of CUAs and IVH may indeed be increased in these FGR/SGA infants when compared with infants not affected by FGR, however the evidence is of low to very low certainty. Further specific cohort studies are needed to fully evaluate the benefits and prognostic value of cranial ultrasonography to ascertain the need for, and timing of a cranial ultrasound screening protocol in this infant population, along with follow-up studies to ascertain the significance of CUAs identified.

Neurodevelopmental consequences of preterm punctate white matter lesions: a systematic review

OBJECTIVES

To evaluate punctate white matter lesion (PWML) influence in preterm infants on the long-term neurodevelopmental outcome (NDO).

METHODS

PubMed and EMBASE were searched from January 1, 2000, to May 31, 2021. Studies were included in which PWML in preterm infants on MRI around term-equivalent age (TEA) and NDO at ≥12 months were reported. Study and patient characteristics and NDO on motor, cognitive, and behavioral domains were extracted. The quality of studies was assessed using the Cochrane-approved Quality in Prognosis Studies tool.

RESULTS

This analysis included nine studies with a total of 1655 patients. Mean incidence of isolated PWML was 22.1%. All studies showed a relationship between PWML and motor delay. Two studies found a significant correlation between cognitive and behavioral outcomes and PWML. Number and PWML location are related to severity and impairment types.

LIMITATIONS

PWML were not always separately described from generalized WMI, only studies with imaging around TEA were included, and studies were heterogenic in design and quality.

CONCLUSIONS

PWML is common in preterm infants and predictive of adverse NDO, in particular on motor outcomes and less on cognitive and behavioral outcomes. The type and severity of impairments are related to the number and location of PMWL.

IMPACT

PWML is common in preterm infants and seems predictive of adverse NDO. DWI and SWI MRI sequences are informative because the different patterns suggest a difference in the underlying pathology. The type and severity of impairments are related to the number and location of PMWL. Our review can inform clinicians and parents about the NDO of preterm infants with a diagnosis of PWML. Prospective neuroimaging case-control cohort studies are recommended.

Impact of Comorbid Prematurity and Congenital Anomalies: A Review

Preterm infants are more likely to be born with congenital anomalies than those who are born at full-term. Conversely, neonates born with congenital anomalies are also more likely to be born preterm than those without congenital anomalies. Moreover, the comorbid impact of prematurity and congenital anomalies is more than cumulative. Multiple common factors increase the risk of brain injury and neurodevelopmental impairment in both preterm babies and those born with congenital anomalies. These include prolonged hospital length of stay, feeding difficulties, nutritional deficits, pain exposure and administration of medications including sedatives and analgesics. Congenital heart disease provides a well-studied example of the impact of comorbid disease with prematurity. Impaired brain growth and maturity is well described in the third trimester in this population; the immature brain is subsequently more vulnerable to further injury. There is a colinear relationship between degree of prematurity and outcome both in terms of mortality and neurological morbidity. Both prematurity and relative brain immaturity independently increase the risk of subsequent neurodevelopmental impairment in infants with CHD. Non-cardiac surgery also poses a greater risk to preterm infants despite the expectation of normal in utero brain growth. Esophageal atresia, diaphragmatic hernia and abdominal wall defects provide examples of congenital anomalies which have been shown to have poorer neurodevelopmental outcomes in the face of prematurity, with associated increased surgical complexity, higher relative cumulative doses of medications, longer hospital and intensive care stay and increased rates of feeding difficulties, compared with infants who experience either prematurity or congenital anomalies alone.

Neonatologist-Performed Cranial Ultrasonography in the Neonatal Intensive Care Unit

Cranial ultrasound (CUS) is an initial screening imaging tool used to evaluate the neonatal brain. It is an accessible, inexpensive, and harmless technique that can be used at bedside as frequently as required. Timely focused CUS in the neonatal care unit can play a major role in the diagnosis, follow-up, and management of brain damage. Despite the increasing use of point-of-care ultrasonography by intensive care physicians, neonatologist-performed CUS remains unusual. This review aims to provide an overview of neonatal CUS to neonatologists, focusing on the optimal settings, standard planes of the brain, and main pathologies in preterm infants. Adding Doppler studies allows evaluation of the patency of intracranial arteries and veins, flow velocities, and indices. This may provide an opportunity for earlier targeted circulatory support to prevent brain injury and improve long-term neurodevelopmental outcomes.

Advanced Brain Imaging in Preterm Infants: A Narrative Review of Microstructural and Connectomic Disruption

Preterm birth disrupts the in utero environment, preventing the brain from fully developing, thereby causing later cognitive and behavioral disorders. Such cerebral alteration occurs beneath an anatomical scale, and is therefore undetectable by conventional imagery. Prematurity impairs the microstructure and thus the histological process responsible for the maturation, including the myelination. Cerebral MRI diffusion tensor imaging sequences, based on water’s motion into the brain, allows a representation of this maturation process. Similarly, the brain’s connections become disorganized. The connectome gathers structural and anatomical white matter fibers, as well as functional networks referring to remote brain regions connected one over another. Structural and functional connectivity is illustrated by tractography and functional MRI, respectively. Their organizations consist of core nodes connected by edges. This basic distribution is already established in the fetal brain. It evolves greatly over time but is compromised by prematurity. Finally, cerebral plasticity is nurtured by a lifetime experience at microstructural and macrostructural scales. A preterm birth causes a negative and early disruption, though it can be partly mitigated by positive stimuli based on developmental neonatal care.

Human Milk and Preterm Infant Brain Development: A Narrative Review

PURPOSE

To review and synthesize the literature on human milk and structural brain development and injury in preterm infants, focusing on the application of quantitative brain magnetic resonance imaging (MRI) in this field.

METHODS

For this narrative review, we searched PubMed for articles published from 1990 to 2021 that reported observational or interventional studies of maternal milk or donor milk in relation to brain development and/or injury in preterm infants assessed with quantitative MRI at term equivalent age. Studies were characterized with respect to key aspects of study design, milk exposure definition, and MRI outcomes.

FINDINGS

We identified 7 relevant studies, all of which were observational in design and published between 2013 and 2021. Included preterm infants were born at or below 33 weeks' gestation. Sample sizes ranged from 22 to 377 infants. Exposure to human milk included both maternal and donor milk. No study included a full-term comparison group. Main MRI outcome domains were white matter integrity (assessed with diffusion tensor imaging, resting state functional connectivity, or semiautomated segmentation of white matter abnormality) and total and regional brain volumes. Studies revealed that greater exposure to human milk versus formula was associated with favorable outcomes, including more mature and connected cerebral white matter with less injury and larger regional brain volumes, notably in the deep nuclear gray matter, amygdala-hippocampus, and cerebellum. No consistent signature effect of human milk exposure was found; instead, the beneficial associations were regional and tissue-specific neuroprotective effects on the areas of known vulnerability in the preterm infant.

IMPLICATIONS

Evidence to date suggests that human milk may protect the preterm infant from the white matter injury and dysmaturation to which this population is vulnerable. Brain MRI at term equivalent age is emerging as a useful tool to investigate the effects of human milk on the preterm brain. When grounded in neurobiological knowledge about preterm brain injury and development, this approach holds promise for allowing further insight into the mechanisms and pathways underlying beneficial associations of human milk with neurodevelopmental outcomes in this population and in the investigation of specific milk bioactive components with neuroprotective or neurorestorative potential.

Expert consensus on the clinical practice of neonatal brain magnetic resonance imaging

In recent years, magnetic resonance imaging (MRI) has been widely used in evaluating neonatal brain development, diagnosing neonatal brain injury, and predicting neurodevelopmental prognosis. Based on current research evidence and clinical experience in China and overseas, the Neonatologist Society of Chinese Medical Doctor Association has developed a consensus on the indications and standardized clinical process of neonatal brain MRI. The consensus has the following main points. (1) Brain MRI should be performed for neonates suspected of hypoxic-ischemic encephalopathy, intracranial infection, stroke and unexplained convulsions; brain MRI is not considered a routine in the management of preterm infants, but it should be performed for further evaluation when cranial ultrasound finds evidence of brain injury; as for extremely preterm or extremely low birth weight infants without abnormal ultrasound findings, it is recommended that they should undergo MRI examination at term equivalent age once. (2) Neonates should undergo MRI examination in a non-sedated state if possible. (3) During MRI examination, vital signs should be closely monitored to ensure safety; the necessity of MRI examination should be strictly evaluated for critically ill neonates, and magnetic resonance compatible incubator and ventilator can be used. (4) At present, 1.5 T or 3.0 T equipment can be used for neonatal brain MRI examination, and the special coil for the neonatal head should be used to improve signal-to-noise ratio; routine neonatal brain MRI sequences should at least include axial T1 weighted image (T1WI), axial T2 weighted imaging (T2WI), diffusion-weighted imaging, and sagittal T1WI or T2WI. (5) It is recommended to use a structured and graded reporting system, and reports by at least two reviewers and multi-center collaboration are recommended to increase the reliability of the report.

Assessment of brain two-dimensional metrics in infants born preterm at term equivalent age: Correlation of ultrasound scans with magnetic resonance imaging

CONTEXT

Developing brain imaging is a critical subject for infants born preterm. Impaired brain growth is correlated with poor neurological outcomes, regardless of overt brain lesions, such as hemorrhage or leukomalacia. As magnetic resonance imaging (MRI) remains a research tool for assessing regional brain volumes, two-dimensional metrics (2D metrics) provide a reliable estimation of brain structures. In neonatal intensive care, cerebral ultrasound (cUS) is routinely performed to assess brain integrity. This prospective work has compared US and MRI accuracy for the measurement of 2D brain metrics and identification of overt injuries.

METHODS

MRI and cUS were performed at term equivalent age (TEA) in infants born before 32 weeks of gestation (GW). Demographical data and results of serial cUS (Neonatal Intensive Care Unit [NICU]-US) performed during hospitalization were gathered from medical charts. Blinded, experienced senior doctors reviewed the scans for both standard analysis and standardized, 2D measurements. The correlation of 2D metrics and inter-/intraobserver agreements were evaluated using Pearson's coefficient, Bland-Altman plots, and intraclass coefficient (ICC), respectively.

RESULTS

In total, 102 infants born preterm were included. The performance of "TEA-cUS and NICU-cUS" when compared to "TEA-MRI and NICU-cUS" was identical for the detection of high-grade hemorrhages and close for low-grade ones. However, TEA-MRI only detected nodular lesions of the white matter (WM). No infant presented a cerebellar infarct on imaging. Intra- and inter-observer agreements were excellent for all 2D metrics except for the corpus callosum width (CCW) and anteroposterior vermis diameter. MRI and cUS showed good to excellent correlation for brain and bones biparietal diameters, corpus callosum length (CCL), transcerebellar diameters (TCDs), and lateral ventricle diameters. Measures of CCW and vermis dimensions were poorly correlated.

CONCLUSION AND PERSPECTIVE

The cUS is a reliable tool to assess selected 2D measurements in the developing brain. Repetition of these metrics by serial cUS during NICU stay would allow the completion of growth charts for several brain structures. Further studies will assess whether these charts are relevant markers of neurological outcome.

Clinical experience with an in-NICU magnetic resonance imaging system

OBJECTIVE

To evaluate the utility of the 1 Tesla (1 T) Embrace (Aspect Imaging) neonatal magnetic resonance imaging (MRI) scanner in a level III NICU.

STUDY DESIGN

Embrace brain MRI findings for 207 infants were reviewed, including 32 scans directly compared within 5 days with imaging on a 3 T Siemens Trio. Clinical MRI scan abnormalities were also compared to cranial ultrasound findings.

RESULT

Of the 207 Embrace brain MRIs, 146 (70.5%) were obtained for clinical indications and 61 (29.5%) were research cases. Abnormal findings were found in 80 scans, most commonly hemorrhage and white matter injury. Notable findings included a stroke, medullary brainstem tumor, and polymicrogyria. In the 1 T versus 3 T comparison cohort, results were discordant in only one infant with punctate foci of susceptibility noted only on the 3 T scan.

CONCLUSION

The Embrace MRI scans detected clinically relevant brain abnormalities and in a subset were clinically comparable to 3 T scans.

Association between Term Equivalent Brain Magnetic Resonance Imaging and 2-Year Outcomes in Extremely Preterm Infants: A Report from the Preterm Erythropoietin Neuroprotection Trial Cohort

OBJECTIVES

To compare the term equivalent brain magnetic resonance imaging (MRI) findings between erythropoietin (Epo) treated and placebo control groups in infants 24^0/7-27^6/7 weeks of gestational age and to assess the associations between MRI findings and neurodevelopmental outcomes at 2 years corrected age.

STUDY DESIGN

The association between brain abnormality scores and Bayley Scales of Infant Development, Third Edition at 2 years corrected age was explored in a subset of infants enrolled in the Preterm Erythropoietin Neuroprotection Trial. Potential risk factors for neurodevelopmental outcomes such as treatment assignment, recruitment site, gestational age, inpatient complications, and treatments were examined using generalized estimating equation models.

RESULTS

One hundred ten infants were assigned to Epo and 110 to placebo groups. 27% of MRI scans were rated as normal, and 60%, 10%, and 2% were rated as having mild, moderate, or severe abnormality. Brain abnormality scores did not significantly differ between the treatment groups. Factors that increased the risk of higher brain injury scores included intubation; bronchopulmonary dysplasia; retinopathy of prematurity; opioid, benzodiazepine, or antibiotic treatment >7 days; and periventricular leukomalacia or severe intraventricular hemorrhage diagnosed on cranial ultrasound. Increased global brain abnormality and white matter injury scores at term equivalent were associated with reductions in cognitive, motor, and language abilities at 2 years of corrected age.

CONCLUSIONS

Evidence of brain injury on brain MRIs obtained at term equivalent correlated with adverse neurodevelopmental outcomes as assessed by the Bayley Scales of Infant and Toddler Development, Third Edition at 2 years corrected age. Early Epo treatment had no effect on the MRI brain injury scores compared with the placebo group.