Optimal timing of cerebral MRI in preterm infants to predict long-term neurodevelopmental outcome: a systematic review

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.

Amplitude-integrated EEG recorded at 32 weeks postconceptional age. Correlation with MRI at term

OBJECTIVE

The study aims to establish the role of late aEEG (scored by Burdjalov) in predicting brain maturation as well as abnormalities evaluated at term equivalent age (TEA) by brain MRI.

METHODS

91 infants born before 30 wks gestation underwent an aEEG monitoring at 32 wks postconceptional age (PCA). aEEG, was correlated with TEA MRI, scored by Kidokoro.

RESULTS

A significant correlation between the aEEG score and the MRI scores was found. The same results were obtained for the aEEG continuity score; cyclicity and bandwidth scores were associated with grey matter and cerebellar MRI items. Moreover, a correlation between aEEG and cEEG recorded both at 32 and 40 wks PCA, was found.

CONCLUSIONS

aEEG monitoring can be predictive of MRI findings at TEA, suggesting that it could be implemented as a useful tool to support ultrasound to help identify neonates who will benefit from early intervention services.

Emotional Prosodies Processing and Its Relationship With Neurodevelopment Outcome at 24 Months in Infants of Diabetic Mothers

Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy. Hyperglycemia of pregnancy is a risk not only for later obesity of the offspring but also do harm to their neurodevelopment from fetus. An ERP research has shown that children with autism spectrum disorder (ASD) was characterized by impaired semantic processing. In this study, we used event-related potential (ERP) to assess the procession of different emotional prosodies (happy, fearful, and angry) in neonates of diabetic mothers, compared to the healthy term infants. And to explore whether the ERP measure has potential value for the evaluation of neurodevelopmental outcome in later childhood. A total of 43 full-term neonates were recruited from the neonatology department of Peking University First Hospital from December 1, 2017 to April 30, 2019. They were assigned to infants of diabetic mothers (IDM) group (n = 23) or control group (n = 20) according to their mother's oral glucose tolerance test's (OGTT) result during pregnancy. Using an oddball paradigm, ERP data were recorded while subjects listened to deviation stimulus (20%, happy/fearful/angry prosodies) and standard stimulus (80%, neutral prosody) to evaluate the potential prognostic value of ERP indexes for neurodevelopment at 24 months of age. Results showed that 1) mismatch response (MMR) amplitudes in IDM group were lower than the control; 2) lower MMR amplitude to fearful prosody at frontal lobe was a high risk for increased Modified Checklist for Autism in Toddlers (M-CHAT) scores at 24 months. These findings suggests that hyperglycemia of pregnancy may influence the ability to process emotional prosodies in neonatal brain; it could be reflected by decreased MMR amplitude in response to fearful prosody. Moreover, the decreased MMR amplitude at the frontal lobe may indicated an increased risk of ASD.

Neuroimaging Findings of the High-risk Neonates and Infants Referred to Mofid Children's Hospital

Objectives

Neuroimaging in high-risk neonates and infants is done to help child neurologists predict the future neurodevelopmental outcome of these children. In this study, we assessed high-risk neonates and infants admitted to the NICU or neonatal wards of Mofid children's Hospital, especially regarding clinical development and brain imaging.

Materials & Methods

This cross-sectional study was conducted on 170 patients admitted to the neonatal and NICU ward of Mofid children's Hospital. Considering the inclusion criteria, 112 patients were included in this project. Brain ultrasonography was performed on almost all of these babies by a single radiologist. Some patients underwent a brain CT scan, and brain MRI without contrast was done on the others. These images were interpreted and compared by a single pediatric neuro-radiologist blinded to clinical data. All of these babies were followed up until 18 months of age.

Results

In this study, 57.1% of the patients were male and 42.9% were female. Of 44 patients who obtained Electroencephalogram (EEG) during the hospitalization period with probable seizure, 25 (56.8%) had normal EEGs. Of 89 babies who were examined by ultrasound, 19 (21.3%) had abnormal findings; ventriculomegaly and then germinal matrix hemorrhage (GMH) were the most common abnormalities. Also, 27 cases (71.1%) of 38 patients undergoing a CT scan had abnormal findings. The most common findings were a hypodense area in the white matter and ventriculomegaly. Of 41 patients who underwent MRI between 1 and 27 months, 34 cases (82.9%) had an abnormal MRI. The most common findings were periventricular hyperintensities in 17 cases (41.5%), mildly delayed myelination in 15 cases (36.6%), and severe brain atrophy or thinning of corpus callosum or white matter volume loss in seven cases (17.1%). During the follow-up period, which was 18.55 ± 6.56 months, 79 (70.5%) of the children had normal development and 33 (29.5%) were suffering from a global neurodevelopmental delay. More precisely, 49 (43.7%) and 35 (31.2%) patients had motor development delay and delayed verbal development, respectively. The abnormal findings of brain imaging in the ultrasound, CT scan, and MRI were all significantly associated with an adverse neurodevelopmental outcome (P <0.001, P = 0.02, and P <0.001, respectively).

Conclusion

In this study, we showed that at any time before six months or after one year of age, the result of brain MRI was a strong predictor of the patient's 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.

Brain volumetry in fetuses that deliver very preterm: An MRI pilot study

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Fetuses that subsequently deliver very preterm have a reduction in cortical and extra cerebrospinal fluid volumes.

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If such alterations commence antenatally this suggests a role for earlier administration of neuroprotective agents.

Background

Infants born preterm are at increased risk of neurological complications resulting in significant morbidity and mortality. The exact mechanism and the impact of antenatal factors has not been fully elucidated, although antenatal infection/inflammation has been implicated in both the aetiology of preterm birth and subsequent neurological sequelae. It is therefore hypothesized that processes driving preterm birth are affecting brain development in utero. This study aims to compare MRI derived regional brain volumes in fetuses that deliver < 32 weeks with fetuses that subsequently deliver at term.

Methods

Women at high risk of preterm birth, with gestation 19.4–32 weeks were recruited prospectively. A control group was obtained from existing study datasets. Fetal MRI was performed on a 1.5 T or 3 T MRI scanner: T2-weighted images were obtained of the fetal brain. 3D brain volumetric datsets were produced using slice to volume reconstruction and regional segmentations were produced using multi-atlas approaches for supratentorial brain tissue, lateral ventricles, cerebellum cerebral cortex and extra-cerebrospinal fluid (eCSF). Statistical comparison of control and high-risk for preterm delivery fetuses was performed by creating normal ranges for each parameter from the control datasets and then calculating gestation adjusted z scores. Groups were compared using t-tests.

Results

Fetal image datasets from 24 pregnancies with delivery < 32 weeks and 87 control pregnancies that delivered > 37 weeks were included. Median gestation at MRI of the preterm group was 26.8 weeks (range 19.4–31.4) and control group 26.2 weeks (range 21.7–31.9). No difference was found in supra-tentorial brain volume, ventricular volume or cerebellar volume but the eCSF and cerebral cortex volumes were smaller in fetuses that delivered preterm (p < 0.001 in both cases).

Conclusion

Fetuses that deliver preterm have a reduction in cortical and eCSF volumes. This is a novel finding and needs further investigation. If alterations in brain development are commencing antenatally in fetuses that subsequently deliver preterm, this may present a window for in utero therapy in the future.

Synthetic MRI demonstrates prolonged regional relaxation times in the brain of preterm born neonates with severe postnatal morbidity

BACKGROUND

To identify preterm infants at risk for neurodevelopment impairment that might benefit from early neurorehabilitation, early prognostic biomarkers of future outcomes are needed.

OBJECTIVE

To determine whether synthetic MRI is sensitive to age-related changes in regional tissue relaxation times in the brain of preterm born neonates when scanned at term equivalent age (TEA, 37-42 weeks), and to investigate whether severe postnatal morbidity results in prolonged regional tissue relaxation times.

MATERIALS AND METHODS

This retrospective study included 70 very preterm born infants scanned with conventional and synthetic MRI between January 2017 and June 2019 at TEA. Infants with severe postnatal morbidity were allocated to a high-risk group (n = 22). All other neonates were allocated to a low-risk group (n = 48). Linear regression analysis was performed to determine the relationship between relaxation times and postmenstrual age (PMA) at scan. Analysis of covariance was used to evaluate the impact of severe postnatal morbidity in the high-risk group on T1 and T2 relaxation times. Receiver operating characteristic (ROC) curves were plotted and analysed with area under the ROC curve (AUC) to evaluate the accuracy of classifying high-risk patients based on regional relaxation times.

RESULTS

A linear age-related decrease of T1 and T2 relaxation times correlating with PMA at scan (between 37 and 42 weeks) was found in the deep gray matter, the cerebellum, the cortex, and the posterior limb of the internal capsule (PLIC) (p < .005 each), but not in the global, frontal, parietal, or central white matter. Analysis of covariance for both risk groups, adjusted for PMA, revealed significantly prolonged regional tissue relaxation times in neonates with severe postnatal morbidity, which was best illustrated in the central white matter of the centrum semiovale (T1 Δ = 11.5%, T2 Δ = 13.4%, p < .001) and in the PLIC (T1 Δ = 9.2%, T2 Δ = 6.9%, p < .001). The relaxation times in the PLIC and the central white matter predicted high-risk status with excellent accuracy (AUC range 0.82-0.86).

CONCLUSION

Synthetic MRI-based relaxometry in the brain of preterm born neonates is sensitive to age-related maturational changes close to TEA. Severe postnatal morbidity correlated with a significant delay in tissue relaxation. Synthetic MRI may provide early prognostic biomarkers for neurodevelopment impairment.

The cingulum in very preterm infants relates to language and social-emotional impairment at 2 years of term-equivalent age

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Maturation of specific WM tracts in preterm individuals differs from those of term controls.

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The elastic net logistic regression model was used to identify altered white matter tracts in the preterm brain.

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The alteration of the cingulum in the preterm at near-term correlate with neurodevelopmental scores at 18–22 months of age.

Background

Relative to full-term infants, very preterm infants exhibit disrupted white matter (WM) maturation and problems related to development, including motor, cognitive, social-emotional, and receptive and expressive language processing.

Objective

The present study aimed to determine whether regional abnormalities in the WM microstructure of very preterm infants, as defined relative to those of full-term infants at a near-term age, are associated with neurodevelopmental outcomes at the age of 18–22 months.

Methods

We prospectively enrolled 89 very preterm infants (birth weight < 1500 g) and 43 normal full-term control infants born between 2016 and 2018. All infants underwent a structural brain magnetic resonance imaging scan at near-term age. The diffusion tensor imaging (DTI) metrics of the whole-brain WM tracts were extracted based on the neonatal probabilistic WM pathway. The elastic net logistic regression model was used to identify altered WM tracts in the preterm brain. We evaluated the associations between the altered WM microstructure at near-term age and motor, cognitive, social-emotional, and receptive and expressive language developments at 18–22 months of age, as measured using the Bayley Scales of Infant Development, Third Edition.

Results

We found that the elastic net logistic regression model could classify preterm and full-term neonates with an accuracy of 87.9% (corrected p < 0.008) using the DTI metrics in the pathway of interest with a 10% threshold level. The fractional anisotropy (FA) values of the body and splenium of the corpus callosum, middle cerebellar peduncle, left and right uncinate fasciculi, and right portion of the pathway between the premotor and primary motor cortices (premotor-PMC), as well as the mean axial diffusivity (AD) values of the left cingulum, were identified as contributive features for classification. Increased adjusted AD values in the left cingulum pathway were significantly correlated with language scores after false discovery rate (FDR) correction (r = 0.217, p = 0.043). The expressive language and social-emotional composite scores showed a significant positive correlation with the AD values in the left cingulum pathway (r = 0.226 [p = 0.036] and r = 0.31 [p = 0.003], respectively) after FDR correction.

Conclusion

Our approach suggests that the cingulum pathways of very preterm infants differ from those of full-term infants and significantly contribute to the prediction of the subsequent development of the language and social-emotional domains. This finding could improve our understanding of how specific neural substrates influence neurodevelopment at later ages, and individual risk prediction, thus helping to inform early intervention strategies that address developmental delay.

Synthetic MRI of Preterm Infants at Term-Equivalent Age: Evaluation of Diagnostic Image Quality and Automated Brain Volume Segmentation

BACKGROUND AND PURPOSE

Neonatal MR imaging brain volume measurements can be used as biomarkers for long-term neurodevelopmental outcome, but quantitative volumetric MR imaging data are not usually available during routine radiologic evaluation. In the current study, the feasibility of automated quantitative brain volumetry and image reconstruction via synthetic MR imaging in very preterm infants was investigated.

MATERIALS AND METHODS

Conventional and synthetic T1WIs and T2WIs from 111 very preterm infants were acquired at term-equivalent age. Overall image quality and artifacts of the conventional and synthetic images were rated on a 4-point scale. Legibility of anatomic structures and lesion conspicuity were assessed on a binary scale. Synthetic MR volumetry was compared with that generated via MANTiS, which is a neonatal tissue segmentation toolbox based on T2WI.

RESULTS

Image quality was good or excellent for most conventional and synthetic images. The 2 methods did not differ significantly regarding image quality or diagnostic performance for focal and cystic WM lesions. Dice similarity coefficients had excellent overlap for intracranial volume (97.3%) and brain parenchymal volume (94.3%), and moderate overlap for CSF (75.6%). Bland-Altman plots demonstrated a small systematic bias in all cases (1.7%-5.9%) CONCLUSIONS: Synthetic T1WI and T2WI sequences may complement or replace conventional images in neonatal imaging, and robust synthetic volumetric results are accessible from a clinical workstation in less than 1 minute. Via the above-described methods, volume assessments could be routinely used in daily clinical practice.

Specific cognitive deficits in preschool age correlated with qualitative and quantitative MRI parameters in prematurely born children

BACKGROUND

Cognitive deficits after perinatal brain lesion in preterm infants are among the most common neurodevelopmental disturbances. The relationship between structural changes on at term magnetic resonance imaging (MRI) and cognitive deficits in the preschool age should be a special focus due to timely intervention. The aim of this study was to correlate qualitative and quantitative MRI parameters of perinatal brain lesion in preterm children, on early neonatal MRI and follow up MRI, with general and specific cognitive functions in the preschool age.

METHODS

Twenty-one preterm infants with verified perinatal lesions based on clinical and ultrasound data underwent a brain MRI at term-equivalent age and a second MRI between 3 and 5 years of age. Qualitative and quantitative MRI analyses were done. All subjects underwent cognitive assessment (3-5 years) using Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III) and Developmental Neuropsychological Assessment (NEPSY-II).

RESULTS

Results show that many structural changes on at term MRI and on follow up MRI in preterm born children moderately correlate with specific cognitive deficits in preschool age. At term equivalent MRI, white matter changes and cortical thickness correlate to general and specific cognitive functions in infants born preterm. By analyzing follow up MRI at preschool age, structural changes of different white matter segments, corpus callosum, cortical thickness and lobe volume correlate to some specific cognitive functions.

CONCLUSION

Besides general cognitive delay, specific cognitive deficits in preterm children should be targeted in research and intervention, optimally combined with MRI scanning, providing timely and early intervention of cognitive deficits after perinatal brain lesion. Our results, as well as previously published results, suggest the importance of detailed preschool neuropsychological assessment, prior to enrolment in the school system. Although preliminary, our results expand our understanding of the relationship between early brain developmental lesions and cognitive outcome following premature birth.

Neuroimaging results, short-term assessment of psychomotor development and the risk of autism spectrum disorder in extremely premature infants (≤28 GA) - a prospective cohort study (preliminary report)

OBJECTIVE

Infants ≤28 GA are at particular risk of psychomotor and neurological developmental disorder. They also remain at a higher risk of developing autism spectrum disorder (ASD), characterized by persistent deficits in communication/social interactions and restricted, repetitive behaviors, activities and interests. Monitoring their development by a team of specialists (a neurologist, psychologist, psychiatrist) allows us to make an early diagnosis and to implement appropriate therapy. Neuroimaging studies during the neonatal period may be helpful in clarifying diagnosis and prognosis. Objective: The aim of the study was to search for the interrelation between the results of neuroimaging and the neurological, psychological and psychiatric evaluation at the age of 2.

PATIENTS AND METHODS

Material and methods: Neonates born at ≤28 weeks between 01.06.2013 and 31.12.2015 and hospitalized at NICU were enrolled. We present the results of the first 12 children who have attained 2 years of corrected age and have undergone both neuroimaging, and neurological, psychological and psychiatric assessments. Transfontanel ultrasound was performed according to general standards, MRI between 38 and 42 weeks of corrected age. Neurological examination based on the Denver scale, ASD screening with use of the STAT test and psychological DSR assessment were performed at 2 years of corrected age.

RESULTS

Results: Median GA was 26 weeks and median weight 795 g. The ultrasound examination was normal in 9 cases (75%) and MRI in 4 (33%). Abnormalities in the cerebellum were the main additional information found in MRI as compared to US. Neurological examination was normal in 8 infants (67#37;), in 4 of whom neuroimaging was normal. In 4 (33%) infants the neurological examination was abnormal. Psychomotor development at an average level or above was found in seven (58#37;) children. In 4 of them neuroimaging was normal, whereas 3 had ventricular dilatation and haemorrhagic infarct. There were no abnormalities within the cerebellum in this group. In the remaining 5 children (42#37;) psychomotor development was rated as delayed. All of them had cerebellar haemorrhage. An increased risk of ASD was observed in 4 children who developed cerebellar hemorrhage.

CONCLUSION

Conclusions: 1. The use of MRI at a term-equivalent age may contribute to the prognosis of neurodevelopmental outcomes in extremely premature infants, allowing risk stratification and thus enhancing early monitoring of a child's development and functional status 2. There is a clear tendency towards abnormal psychomotor development and positive screening for ASD to co-occur with abnormal MRI findings in the cerebellum.

Age related signal changes of the pituitary stalk on thin-slice magnetic resonance imaging in infants

PURPOSE

Signals of some brain regions change along with development in T1-weighted imaging (T1WI) in infants. This study aimed to assess the association of the signal intensity of the pituitary stalk on thin-slice T1WI with infant age.

METHODS

This retrospective study was performed in 89 infants (gestational age [GA], 25-41 weeks; postmenstrual age [PMA], 36-46 weeks; chronological age [CA], 4-141 days) without intracranial abnormalities. The signal ratio of the pituitary stalk/pons on thin-slice T1WI was calculated, and its correlations with GA, PMA, and CA were assessed. Additionally, the signal ratio of the anterior pituitary gland/pons was calculated, and its correlation with that of the pituitary stalk was assessed. The signal intensity and distribution of the pituitary stalk were visually rated, and their correlations with GA, PMA, and CA were assessed.

RESULTS

The signal ratio of the pituitary stalk was significantly positively correlated with GA (P < 0.001) and negatively correlated with CA (P < 0.001), but was not correlated with PMA. Stepwise multiple regression revealed that CA was independently associated with the signal ratio of the pituitary stalk (P < 0.001). GA was significantly higher (P < 0.05) and CA was significantly lower (P < 0.05) in infants with a high signal intensity and wide distribution of high signal intensity of the pituitary stalk.

CONCLUSIONS

The signal intensity of the pituitary stalk on T1WI was negatively correlated with CA in infants, which might be related to postnatal changes in the pars tuberalis of the pituitary stalk after birth in infants.

Cranial ultrasound and neurophysiological testing to predict neurological outcome in infants born very preterm

AIM

Infants born preterm are at risk of cerebral palsy (CP) and motor or cognitive developmental delay. For clinicians, it is essential to know the relative predictive accuracy of the most commonly used neuroimaging and neurophysiological tests for the early prediction of adverse neurodevelopmental outcome. The aim of this study was to compare the accuracy of these tests in survivors of a population of infants born very preterm.

METHOD

A retrospective cohort study was performed in 163 children born before 32 weeks gestational age. We compared the accuracy in predicting adverse neurodevelopmental outcome at the age of 2 years 6 months of early and late cranial ultrasound (CUS), magnetic resonance imaging, somatosensory evoked potentials after stimulation of the posterior tibial nerve, and electroencephalography by calculating positive and negative likelihood ratios.

RESULTS

An abnormal early CUS is the best predictor of the presence of CP (positive likelihood ratio 6.09), motor developmental delay (positive likelihood ratio 3.11), and cognitive developmental delay (positive likelihood ratio 5.66). Overall, negative likelihood ratios were poor, ranging between 0.49 and 0.98, meaning that a normal test result had only minimal influence on the probability of adverse neurological outcome.

INTERPRETATION

None of the diagnostic tests had a good performance in predicting future neurodevelopmental problems in infants born preterm. A normal test result provided very little clinically useful information.

WHAT THIS PAPER ADDS

An abnormal early cranial ultrasound (positive test result) is the best predictor of adverse neurodevelopmental outcome. All negative results have poor predictive value of future neurodevelopmental problems.

Neuroimaging for Neurodevelopmental Prognostication in High-Risk Neonates

Predicting neurodevelopmental outcomes in high-risk neonates remains challenging despite advances in neonatal care. Early and accurate characterization of infants at risk for neurodevelopmental delays is necessary to best identify those who may benefit from existing early interventions and novel therapies that become available. Although neuroimaging is a promising biomarker in the prediction of neurodevelopmental outcomes in high-risk infants, it requires additional resources and expertise. Despite many advances in neonatal neuroimaging, there remain limitations in relating early neuroimaging findings with long-term outcomes; further studies are necessary to determine the optimal protocols to best identify high-risk patients and improve neurodevelopmental outcome prediction.

Body length and occipitofrontal circumference may be good indicators of neurodevelopment in very low birthweight infants - secondary publication

AIM

The aim of this study was to predict the neurological prognosis of very low birthweight (VLBW) infants. We examined the relationship between nutritional status, brain volume measured by magnetic resonance imaging (MRI) and anthropometric measurements of VLBW infants at term-equivalent age (TEA).

METHODS

We evaluated 27 VLBW infants, born at Showa University Hospital in Japan between April 2012 and August 2013, who underwent brain MRI at TEA. Based on their clinical data, we analysed their protein and energy intake.

RESULTS

Median values for the 27 VLBW infants were as follows: gestational age, 29.7 weeks; birthweight 1117 g; protein intake 2.7 g/kg/day and energy intake 97.9 kcal/kg/day. At TEA, the standard deviation scores (SDSs) of body weight, body length and the occipitofrontal circumference (OFC) were -0.8, -1.4 and 0.7, respectively. Multiple regression analysis revealed that the SDSs of body length and the OFC at TEA were significant determinants of white matter volume, but that the SDS of body weight at TEA was not.

CONCLUSION

Our findings suggest that the SDSs of body length and the OFC at TEA may be better indicators than body weight for predicting the development of the central nervous system in VLBW infants receiving nutritional management.

Neuroimaging results, short-term assessment of psychomotor development and the risk of autism spectrum disorder in extremely premature infants (≤28 GA) - a prospective cohort study (preliminary report)

OBJECTIVE

Infants ≤28 GA are at particular risk of psychomotor and neurological developmental disorder. They also remain at a higher risk of developing autism spectrum disorder (ASD), characterized by persistent deficits in communication/social interactions and restricted, repetitive behaviors, activities and interests. Monitoring their development by a team of specialists (a neurologist, psychologist, psychiatrist) allows us to make an early diagnosis and to implement appropriate therapy. Neuroimaging studies during the neonatal period may be helpful in clarifying diagnosis and prognosis. Objective: The aim of the study was to search for the interrelation between the results of neuroimaging and the neurological, psychological and psychiatric evaluation at the age of 2.

PATIENTS AND METHODS

Material and methods: Neonates born at ≤28 weeks between 01.06.2013 and 31.12.2015 and hospitalized at NICU were enrolled. We present the results of the first 12 children who have attained 2 years of corrected age and have undergone both neuroimaging, and neurological, psychological and psychiatric assessments. Transfontanel ultrasound was performed according to general standards, MRI between 38 and 42 weeks of corrected age. Neurological examination based on the Denver scale, ASD screening with use of the STAT test and psychological DSR assessment were performed at 2 years of corrected age.

RESULTS

Results: Median GA was 26 weeks and median weight 795 g. The ultrasound examination was normal in 9 cases (75%) and MRI in 4 (33%). Abnormalities in the cerebellum were the main additional information found in MRI as compared to US. Neurological examination was normal in 8 infants (67#37;), in 4 of whom neuroimaging was normal. In 4 (33%) infants the neurological examination was abnormal. Psychomotor development at an average level or above was found in seven (58#37;) children. In 4 of them neuroimaging was normal, whereas 3 had ventricular dilatation and haemorrhagic infarct. There were no abnormalities within the cerebellum in this group. In the remaining 5 children (42#37;) psychomotor development was rated as delayed. All of them had cerebellar haemorrhage. An increased risk of ASD was observed in 4 children who developed cerebellar hemorrhage.

CONCLUSION

Conclusions: 1. The use of MRI at a term-equivalent age may contribute to the prognosis of neurodevelopmental outcomes in extremely premature infants, allowing risk stratification and thus enhancing early monitoring of a child's development and functional status 2. There is a clear tendency towards abnormal psychomotor development and positive screening for ASD to co-occur with abnormal MRI findings in the cerebellum.

Cerebellar Growth Impairment Characterizes School-Aged Children Born Preterm without Perinatal Brain Lesions

BACKGROUND AND PURPOSE

Infants born preterm are commonly diagnosed with structural brain lesions known to affect long-term neurodevelopment negatively. Yet, the effects of preterm birth on brain development in the absence of intracranial lesions remain to be studied in detail. In this study, we aim to quantify long term consequences of preterm birth on brain development in this specific group.

MATERIALS AND METHODS

Neonatal cranial sonography and follow-up T1-weighted MR imaging and DTI were performed to evaluate whether the anatomic characteristics of the cerebrum and cerebellum in a cohort of school-aged children (6-12 years of age) were related to gestational age at birth in children free of brain lesions in the perinatal period.

RESULTS

In the cohort consisting of 36 preterm (28-37 weeks' gestational age) and 66 term-born infants, T1-weighted MR imaging and DTI at 6-12 years revealed a reduction of cerebellar white matter volume (β = 0.387, P < .001), altered fractional anisotropy of cerebellar white matter (β = -0.236, P = .02), and a reduction of cerebellar gray and white matter surface area (β = 0.337, P < .001; β = 0.375, P < .001, respectively) in relation to birth age. Such relations were not observed for the cerebral cortex or white matter volume, surface area, or diffusion quantities.

CONCLUSIONS

The results of our study show that perinatal influences that are not primarily neurologic are still able to disturb long-term neurodevelopment, particularly of the developing cerebellum. Including the cerebellum in future neuroprotective strategies seems therefore essential.

Diagnostic accuracy of early magnetic resonance imaging to determine motor outcomes in infants born preterm: a systematic review and meta-analysis

AIM

To examine the diagnostic ability of early magnetic resonance imaging (MRI; <36wks postmenstrual age) to detect later adverse motor outcomes or cerebral palsy (CP) in infants born preterm.

METHOD

Studies of infants born preterm with MRI earlier than 36 weeks postmenstrual age and quantitative motor data or a diagnosis of CP at or beyond 1 year corrected age were identified. Study details were extracted and meta-analyses performed where possible. Quality of included studies was evaluated with the QUADAS-2 (a revised tool for the quality assessment of diagnostic accuracy studies).

RESULTS

Thirty-one articles met the inclusion criteria, five of which reported diagnostic accuracy and five reported data sufficient for calculation of diagnostic accuracy. Early structural MRI global scores detected a later diagnosis of CP with a pooled sensitivity of 100% (95% confidence interval [CI] 86-100) and a specificity of 93% (95% CI 59-100). Global structural MRI scores determined adverse motor outcomes with a pooled sensitivity of 89% (95% CI 44-100) and a specificity of 98% (95% CI 90-100). White matter scores determined adverse motor outcomes with a pooled sensitivity of 33% (95% CI 20-48) and a specificity of 83% (95% CI 78-88).

INTERPRETATION

Early structural MRI has reasonable sensitivity and specificity to determine adverse motor outcomes and CP in infants born preterm. Greater reporting of diagnostic accuracy in studies examining relationships with motor outcomes and CP is required to facilitate clinical utility of early MRI.

WHAT THIS PAPER ADDS

Early magnetic resonance imaging (MRI) has reasonable sensitivity and specificity to determine later adverse motor outcomes and cerebral palsy (CP). Detection of infants who progressed to CP was stronger than motor outcomes. Global MRI scores determined adverse motor outcomes more accurately than white matter scores. Few studies report diagnostic accuracy of early MRI findings. Diagnostic accuracy is required to draw clinically meaningful conclusions from early MRI studies.

Cerebral White Matter Maturation Patterns in Preterm Infants: An MRI T2 Relaxation Anisotropy and Diffusion Tensor Imaging Study

BACKGROUND AND PURPOSE

Preterm birth is associated with worse neurodevelopmental outcome, but brain maturation in preterm infants is poorly characterized with standard methods. We evaluated white matter (WM) of infant brains at term-equivalent age, as a function of gestational age at birth, using multimodal magnetic resonance imaging (MRI).

METHODS

Infants born very preterm (<32 weeks gestation) and late preterm (33-36 weeks gestation) were scanned at 3 T at term-equivalent age using diffusion tensor imaging (DTI) and T2 relaxometry. MRI data were analyzed using tract-based spatial statistics, and anisotropy of T2 relaxation was also determined. Principal component analysis and linear discriminant analysis were applied to seek the variables best distinguishing very preterm and late preterm groups.

RESULTS

Across widespread regions of WM, T2 is longer in very preterm infants than in late preterm ones. These effects are more prevalent in regions of WM that myelinate earlier and faster. Similar effects are obtained from DTI, showing that fractional anisotropy (FA) is lower and radial diffusivity higher in the very preterm group, with a bias toward earlier myelinating regions. Discriminant analysis shows high sensitivity and specificity of combined T2 relaxometry and DTI for the detection of a distinct WM development pathway in very preterm infants. T2 relaxation is anisotropic, depending on the angle between WM fiber and magnetic field, and this effect is modulated by FA.

CONCLUSIONS

Combined T2 relaxometry and DTI characterizes specific patterns of retarded WM maturation, at term equivalent age, in infants born very preterm relative to late preterm.

Regional volumetric assessment of the brain in moderately preterm infants (30-35 gestational weeks) scanned at term-equivalent age on magnetic resonance imaging

BACKGROUND

Early volume analyses of the infantile brain may help predict neurodevelopmental outcome. However, brain volumes are not well understood in moderately preterm infants at term-equivalent age (TEA).

AIM

This study retrospectively investigated the relationship between regional brain volumes and infant gestational age (GA) at birth in moderately preterm infants (30-35weeks' GA) on magnetic resonance imaging (MRI) at TEA.

METHODS

Forty infants scanned at TEA were enrolled. Regional brain volumes were estimated by manual segmentation on MRI, and their relationship with GA at birth was assessed.

RESULTS

The regional volumes of the cerebral hemispheres and deep gray matter were larger (Spearman ρ=0.40, P=0.01, and Spearman ρ=0.48, P<0.01, respectively), and volumes of the lateral ventricles were smaller (Spearman ρ=-0.32, P=0.04) in infants born at a later GA. The volumes of the cerebral hemispheres of the infants born at 30weeks' GA were significantly smaller than those born at 33 and 35weeks' GA (P<0.05). No associations were found between the volume of the cerebellum and brainstem, and GA at birth (Spearman ρ=0.24, P=0.13, and Spearman ρ=0.24, P=0.14, respectively).

CONCLUSIONS

The volumes of the cerebral hemispheres at TEA may be smaller in infants born at 30weeks' GA, whereas those of the cerebellum and brainstem may not be correlated with GA among moderately preterm infants.

Comparison of preterm and term equivalent age MRI for the evaluation of preterm brain injury

OBJECTIVE

To compare information obtained from preterm magnetic resonance imaging (MRI; 31-34 weeks) brain scan to that done at term equivalent age.

STUDY DESIGN

Prospective observational study of premature infants with evidence or suspicion of parenchymal brain injury on cranial ultrasound. Brain injury on two scans scored using a scoring system and analyzed.

RESULTS

Fourteen infants with a median (range) gestation at birth of 28 (25-29) weeks and birth weight of 1254 (680-1557) grams were studied. There was a strong correlation between the brain injury scores for the two scans (Spearman ρ=0.87, P=0.001) with excellent agreement between two radiologists (interclass correlation coefficient 0.9-0.94). There was also a high level of agreement between the preterm and term MRI two scores (Intraclass correlation coefficient, 0.79 (0.53-0.94)).

CONCLUSIONS

Preterm MRI is a feasible option for the assessment of preterm brain injury and analysis of data obtained from scan at preterm age is comparable to that obtained at term equivalent age.

Correlation among Magnetic Resonance Imaging Parameters of Brain in Preterm Neonates at Term Equivalent Age

OBJECTIVES

To assess the spectrum of Magnetic Resonance Imaging (MRI) abnormalities among preterm babies at term equivalent age using objective scoring and to study the association among MRI variables.

METHODS

Ninety-four preterm babies born at ≤32 wk of gestation and / or birth weight ≤ 1500 g at term equivalent age who underwent cranial MRI between April 2011 and August 2012 and the MRI interpreted by experienced radiologists were studied. In 2014, the MRI was retrospectively re-interpreted by the same radiologists using an objective scoring system described by Kidokoro. Spectrum of MRI abnormalities, their association with perinatal variables and correlation among white matter (WM), grey matter and cerebellar scores were analyzed.

RESULTS

MRI abnormalities observed were WM signal abnormality (24 %), lateral ventricular dilatation (16 %), WM cystic abnormality (13 %), deep grey matter signal abnormality (9 %), cerebellar volume reduction (9 %) and deep grey matter volume reduction (8 %). Sepsis was significantly associated with occurrence of WM and cerebellar abnormalities (p < 0.05). WM scores did not show significant correlation with cortical grey matter and deep grey matter scores while cerebellar scores showed a weak positive correlation with WM (r = 0.33), cortical grey matter (r = 0.27) and deep grey matter scores (r = 0.22).

CONCLUSIONS

MRI abnormalities are common in preterm infants, with 60 % showing some abnormality at term equivalent age. Among perinatal characteristics, sepsis was identified as risk factor for WM and cerebellar injury. Grey matter abnormality occurs independent of WM abnormality. Cerebellar abnormalities appear to coexist with either WM or grey matter changes.

Neonatal diffusion tensor brain imaging predicts later motor outcome in preterm neonates with white matter abnormalities

BACKGROUND

White matter (WM) abnormalities associated with prematurity are one of the most important causes of neurological disability that involves spastic motor deficits in preterm newborns. This study aimed to evaluate regional microstructural changes in diffusion tensor imaging (DTI) associated with WM abnormalities.

METHODS

We prospectively studied extremely low birth weight (ELBW; <1000 g) preterm infants who were admitted to the Neonatal Intensive Care Unit of Hanyang University Hospital between February 2011 and February 2014. WM abnormalities were assessed with conventional magnetic resonance (MR) imaging and DTI near term-equivalent age before discharge. Region-of-interests (ROIs) measurements were performed to examine the regional distribution of fractional anisotropy (FA) values.

RESULTS

Thirty-two out of 72 ELBW infants underwent conventional MR imaging and DTI at term-equivalent age. Ten of these infants developed WM abnormalities associated with prematurity. Five of ten of those with WM abnormalities developed cerebral palsy (CP). DTI in the WM abnormalities with CP showed a significant reduction of mean FA in the genu of the corpus callosum (p = 0.022), the ipsilateral posterior limb of the internal capsule (p = 0.019), and the ipsilateral centrum semiovale (p = 0.012) compared to normal WM and WM abnormalities without CP. In infants having WM abnormalities with CP, early FA values in neonatal DTI revealed abnormalities of the WM regions prior to the manifestation of hemiparesis.

CONCLUSIONS

DTI performed at term equivalent age shows different FA values in WM regions among infants with or without WM abnormalities associated with prematurity and/or CP. Low FA values of ROIs in DTI are related with later development of spastic CP in preterm infants with WM abnormalities.

Size of the intracranial optic nerve and optic tract in neonates at term-equivalent age at magnetic resonance imaging

BACKGROUND

The expected MRI-based dimensions of the intracranial optic nerve and optic tract in neonates are unknown.

OBJECTIVE

To evaluate the sizes of the intracranial optic nerve and optic tract in neonates at term-equivalent age using MRI.

MATERIALS AND METHODS

We retrospectively analyzed brain MRI examinations in 62 infants (28 boys) without intracranial abnormalities. The images were obtained in infants at term-equivalent age with a 1.5-tesla MRI scanner. We measured the widths and heights of the intracranial optic nerve and optic tract and calculated the cross-sectional areas using the formula for an ellipse.

RESULTS

The means ± standard deviation of the width, height and cross-sectional area of the intracranial optic nerve were 2.7 ± 0.2 mm, 1.7 ± 0.2 mm and 3.5 ± 0.5 mm(2), respectively. The width, height and cross-sectional area of the optic tract were 1.5 ± 0.1 mm, 1.6 ± 0.1 mm and 2.0 ± 0.2 mm(2), respectively. Using univariate and multivariate analyses, we found that postmenstrual age showed independent intermediate positive correlations with the width (r = 0.48, P < 0.01) and cross-sectional area (r = 0.40, P < 0.01) of the intracranial optic nerve. The lower bounds of the 95% prediction intervals for the width and cross-sectional area of the intracranial optic nerve were 0.07 × (postmenstrual age in weeks) - 0.46 mm, and 0.17 × (postmenstrual age in weeks) - 4.0 mm(2), respectively.

CONCLUSION

We identified the sizes of the intracranial optic nerve and optic tract in neonates at term-equivalent age. The postmenstrual age at MRI independently positively correlated with the sizes.

Surgical Necrotizing Enterocolitis versus Spontaneous Intestinal Perforation in White Matter Injury on Brain Magnetic Resonance Imaging

BACKGROUND

White matter injury (WMI) is the most common form of brain injury in preterm infants. It could be induced by a systemic inflammatory response in preterm infants.

OBJECTIVES

We hypothesized that surgical necrotizing enterocolitis (surgNEC) results in more severe WMI than spontaneous intestinal perforation (SIP) on brain magnetic resonance imaging (MRI) at term-equivalent age (TEA).

METHODS

The medical records of 33 preterm infants born at less than 32 weeks of gestation who underwent surgery due to either NEC or SIP were reviewed retrospectively. White matter abnormality (WMA) on brain MRI was scored according to the diagnosis of surgNEC or SIP.

RESULTS

Nine patients were diagnosed with SIP and 24 with surgNEC. The median (range) gestational age of the SIP and surgNEC groups was 26+6 (23+3-27+6) and 25+5 weeks (23+3-31+2), respectively (p = 0.454). There were no differences in 1- and 5-min Apgar scores, mode of delivery, use of antenatal steroids, histologic chorioamnionitis, or incidence of respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD) between the two groups. Males were more prevalent in the surgNEC group (75.0 vs. 33.3%, p = 0.044), and the incidence of sepsis was higher in the surgNEC group than in the SIP group (75.0 vs. 33.3%, p = 0.044). Multivariate regression showed that the difference in WMA scores between the two groups remained significant (estimated difference = 2.418; 95% CI 0.107-4.729).

CONCLUSION

In preterm infants at less than 32 weeks of gestation, those with surgNEC showed more severe WMI than infants with SIP on brain MRI at TEA.

Lipopolysaccharide-Induced Preconditioning Attenuates Apoptosis and Differentially Regulates TLR4 and TLR7 Gene Expression after Ischemia in the Preterm Ovine Fetal Brain

Acute exposure to subclinical infection modulates subsequent hypoxia-ischemia (HI) injury in a time-dependent manner, likely by cross-talk through Toll-like receptors (TLRs), but the specific pathways are unclear in the preterm-equivalent brain. In the present study, we tested the hypothesis that repeated low-dose exposure to lipopolysaccharide (LPS) before acute ischemia would be associated with induction of specific TLRs that are potentially neuroprotective. Fetal sheep at 0.65 gestation (term is ∼145 days) received intravenous boluses of low-dose LPS for 5 days (day 1, 50 ng/kg; days 2-5, 100 ng/kg) or the same volume of saline. Either 4 or 24 h after the last bolus of LPS, complete carotid occlusion was induced for 22 min. Five days after LPS, brains were collected. Pretreatment with LPS for 5 days decreased cellular apoptosis, microglial activation and reactive astrogliosis in response to HI injury induced 24 but not 4 h after the last dose of LPS. This was associated with upregulation of TLR4, TLR7 and IFN-β mRNA, and increased fetal plasma IFN-β concentrations. The association of reduced white matter apoptosis and astrogliosis after repeated low-dose LPS finishing 24 h but not 4 h before cerebral ischemia, with central and peripheral induction of IFN-β, suggests the possibility that IFN-β may be an important mediator of endogenous neuroprotection in the developing brain.

Serial cranial ultrasonography or early MRI for detecting preterm brain injury?

OBJECTIVE

To investigate detection ability and feasibility of serial cranial ultrasonography (CUS) and early MRI in preterm brain injury.

DESIGN

Prospective cohort study.

SETTING

Level III neonatal intensive care unit.

PATIENTS

307 infants, born below 29 weeks of gestation.

METHODS

Serial CUS and MRI were performed according to standard clinical protocol. In case of instability, MRI was postponed or cancelled. Brain images were assessed by independent experts and compared between modalities.

MAIN OUTCOME MEASURES

Presence of preterm brain injury on either CUS or MRI and discrepant imaging findings on CUS and MRI.

RESULTS

Serial CUS was performed in all infants; early MRI was often postponed (n=59) or cancelled (n=126). Injury was found in 146 infants (47.6%). Clinical characteristics differed significantly between groups that were subdivided according to timing of MRI. 61 discrepant imaging findings were found. MRI was superior in identifying cerebellar haemorrhage; CUS in detection of acute intraventricular haemorrhage, perforator stroke and cerebral sinovenous thrombosis.

CONCLUSIONS

Advanced serial CUS seems highly effective in diagnosing preterm brain injury, but may miss cerebellar abnormalities. Although MRI does identify these lesions, feasibility is limited. Improved safety, better availability and tailored procedures are essential for MRI to increase its value in clinical care.

MRI evaluation and safety in the developing brain

Magnetic resonance imaging (MRI) evaluation of the developing brain has dramatically increased over the last decade. Faster acquisitions and the development of advanced MRI sequences, such as magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI), perfusion imaging, functional MR imaging (fMRI), and susceptibility-weighted imaging (SWI), as well as the use of higher magnetic field strengths has made MRI an invaluable tool for detailed evaluation of the developing brain. This article will provide an overview of the use and challenges associated with 1.5-T and 3-T static magnetic fields for evaluation of the developing brain. This review will also summarize the advantages, clinical challenges, and safety concerns specifically related to MRI in the fetus and newborn, including the implications of increased magnetic field strength, logistics related to transporting and monitoring of neonates during scanning, and sedation considerations, and a discussion of current technologies such as MRI conditional neonatal incubators and dedicated small-foot print neonatal intensive care unit (NICU) scanners.

Data quality in diffusion tensor imaging studies of the preterm brain: a systematic review

BACKGROUND

To study early neurodevelopment in preterm infants, evaluation of brain maturation and injury is increasingly performed using diffusion tensor imaging, for which the reliability of underlying data is paramount.

OBJECTIVE

To review the literature to evaluate acquisition and processing methodology in diffusion tensor imaging studies of preterm infants.

MATERIALS AND METHODS

We searched the Embase, Medline, Web of Science and Cochrane databases for relevant papers published between 2003 and 2013. The following keywords were included in our search: prematurity, neuroimaging, brain, and diffusion tensor imaging.

RESULTS

We found 74 diffusion tensor imaging studies in preterm infants meeting our inclusion criteria. There was wide variation in acquisition and processing methodology, and we found incomplete reporting of these settings. Nineteen studies (26%) reported the use of neonatal hardware. Data quality assessment was not reported in 13 (18%) studies. Artefacts-correction and data-exclusion was not reported in 33 (45%) and 18 (24%) studies, respectively. Tensor estimation algorithms were reported in 56 (76%) studies but were often suboptimal.

CONCLUSION

Diffusion tensor imaging acquisition and processing settings are incompletely described in current literature, vary considerably, and frequently do not meet the highest standards.

Choice of diffusion tensor estimation approach affects fiber tractography of the fornix in preterm brain

BACKGROUND AND PURPOSE

Neonatal DTI enables quantitative assessment of microstructural brain properties. Although its use is increasing, it is not widely known that vast differences in tractography results can occur, depending on the diffusion tensor estimation methodology used. Current clinical work appears to be insufficiently focused on data quality and processing of neonatal DTI. To raise awareness about this important processing step, we investigated tractography reconstructions of the fornix with the use of several estimation techniques. We hypothesized that the method of tensor estimation significantly affects DTI tractography results.

MATERIALS AND METHODS

Twenty-eight DTI scans of infants born <29 weeks of gestation, acquired at 30-week postmenstrual age and without intracranial injury observed, were prospectively collected. Four diffusion tensor estimation methods were applied: 1) linear least squares; 2) weighted linear least squares; 3) nonlinear least squares, and 4) robust estimation of tensors by outlier rejection. Quality of DTI data and tractography results were evaluated for each method.

RESULTS

With nonlinear least squares and robust estimation of tensors by outlier rejection, significantly lower mean fractional anisotropy values were obtained than with linear least squares and weighted linear least squares. Visualized quality of tract reconstruction was significantly higher by use of robust estimation of tensors by outlier rejection and correlated with quality of DTI data.

CONCLUSIONS

Quality assessment and choice of processing methodology have considerable impact on neonatal DTI analysis. Dedicated acquisition, quality assessment, and advanced processing of neonatal DTI data must be ensured before performing clinical analyses, such as associating microstructural brain properties with patient outcome.