Neurodevelopmental Outcomes in Preterm Infants: Comparison of Infants with and without Diffuse Excessive High Signal Intensity on MR Images at Near–term-equivalent Age

On punctate white matter lesions in preterm infants: Is ultrasound diagnosis feasible?

OBJECTIVES

To observe hyperechoic nodular or punctate white matter lesions (HNPL) in a population of preterm infants using routine cranial ultrasound (cUS), to describe the characteristics of HNPL, and to compare them with punctate white matter lesions (PWML) detected in magnetic resonance imaging (MRI).

DESIGN

Retrospective observational single-center cohort study.

SETTING

Level 2B neonatal unit in France.

PATIENTS

307 infants born <33 weeks gestation undergoing routine cUS with a total of 961 cUS performed.

MAIN OUTCOME MEASURES

Description of lesions (HNPL/PWML): presence or absence, number, size, location, and structural distribution.

RESULTS

Among the 307 included infants, 63 (20.5%) had at least one cerebral lesion, with 453 HNPL for 63 infants. HNPL were numerous (more than three in 66.6% of cases), primarily grouped in clusters (76.2%), located near the lateral ventricles (96.8%), and measuring more than 2 mm (79%). HNPL were diagnosed on day 29 on average and persisted until term. Overall, 43 MRI were performed in 307 infants, on average 18.9 days after last cUS, in 21 of those the indication was presence of HPNL on cUS. Of these 21 MRI, 14/21 presented 118 PWML compared to 173 HNPL on cUS. In the remaining MRI (7/21), no PWML were detected compared to 47 HNPL on cUS.

CONCLUSIONS

In our population of 307 preterm infants, cUS allowed the diagnosis of HNPL, with a large similarity to PWML in MRI and a better sensitivity. But in the absence of data on inter-observer variability, we cannot exclude overdiagnosis of HNPL.

Diffuse excessive high signal intensity in the preterm brain on advanced MRI represents widespread neuropathology

Preterm brains commonly exhibit elevated signal intensity in the white matter on T2-weighted MRI at term-equivalent age. This signal, known as diffuse excessive high signal intensity (DEHSI) or diffuse white matter abnormality (DWMA) when quantitatively assessed, is associated with abnormal microstructure on diffusion tensor imaging. However, postmortem data are largely lacking and difficult to obtain, and the pathological significance of DEHSI remains in question. In a cohort of 202 infants born preterm at ≤32 weeks gestational age, we leveraged two newer diffusion MRI models - Constrained Spherical Deconvolution (CSD) and neurite orientation dispersion and density index (NODDI) - to better characterize the macro and microstructural properties of DWMA and inform the ongoing debate around the clinical significance of DWMA. With increasing DWMA volume, fiber density broadly decreased throughout the white matter and fiber cross-section decreased in the major sensorimotor tracts. Neurite orientation dispersion decreased in the centrum semiovale, corona radiata, and temporal lobe. These findings provide insight into DWMA's biological underpinnings and demonstrate that it is a serious pathology.

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.

Diffuse white matter abnormality in very preterm infants at term reflects reduced brain network efficiency

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Most preterm infants exhibit regions of high signal intensity on T2 MRI at term.

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Debate remains as to whether this signal (DWMA) is pathological.

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We quantified DWMA and used graph theory to measure brain network efficiency.

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Whole-brain and regional network efficiency at term decreased with greater DWMA.

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DWMA in very preterm infants is associated with reduced brain efficiency at term.

Between 50 and 80% of very preterm infants (<32 weeks gestational age) exhibit increased white matter signal intensity on T2-weighted MRI at term-equivalent age, known as diffuse white matter abnormality (DWMA). A few studies have linked DWMA with microstructural abnormalities, but the exact relationship remains poorly understood. We related DWMA extent to graph theory measures of network efficiency at term in a representative cohort of 343 very preterm infants. We performed anatomic and diffusion MRI at term and quantified DWMA volume with our novel, semi-automated algorithm. From diffusion-weighted structural connectomes, we calculated the graph theory metrics local efficiency and clustering coefficient, which measure the ability of groups of nodes to perform specialized processing, and global efficiency, which assesses the ability of brain regions to efficiently combine information. We computed partial correlations between these measures and DWMA volume, adjusted for confounders. Increasing DWMA volume was associated with decreased global efficiency of the entire very preterm brain and decreased local efficiency and clustering coefficient in a variety of regions supporting cognitive, linguistic, and motor function. We show that DWMA is associated with widespread decreased brain network efficiency, suggesting that it is pathologic and likely has adverse developmental consequences.

Perinatal Risk and Protective Factors in the Development of Diffuse White Matter Abnormality on Term-Equivalent Age Magnetic Resonance Imaging in Infants Born Very Preterm

OBJECTIVE

To identify perinatal clinical diseases and treatments that are associated with the development of objectively diagnosed diffuse white matter abnormality (DWMA) on structural magnetic resonance imaging (MRI) at term-equivalent age in infants born very preterm.

STUDY DESIGN

A prospective cohort of 392 infants born very preterm (≤32 weeks of gestational age) was enrolled from 5 level III/IV neonatal intensive care units between September 2016 and November 2019. MRIs of the brain were collected at 39 to 45 weeks of postmenstrual age to evaluate DWMA volume. A predefined list of pertinent maternal characteristics, pregnancy/delivery data, and neonatal intensive care unit data were collected for enrolled patients to identify antecedents of objectively diagnosed DWMA.

RESULTS

Of the 392 infants in the cohort, 377 (96%) had high-quality MRI data. Their mean (SD) gestational age was 29.3 (2.5) weeks. In multivariable linear regression analyses, pneumothorax (P = .027), severe bronchopulmonary dysplasia (BPD) (P = .009), severe retinopathy of prematurity (P < .001), and male sex (P = .041) were associated with increasing volume of DWMA. The following factors were associated with decreased risk of DWMA: postnatal dexamethasone therapy for severe BPD (P = .004), duration of caffeine therapy for severe BPD (P = .009), and exclusive maternal milk diet at neonatal intensive care unit discharge (P = .049).

CONCLUSIONS

Severe retinopathy of prematurity and BPD exhibited the strongest adverse association with development of DWMA. We also identified treatments and nutritional factors that appear protective against the development of DWMA that also have implications for the clinical care of infants born very preterm.

Comparative performance of head ultrasound and MRI in detecting preterm brain injury and predicting outcomes: A systematic review

AIM

To systematically review the literature to compare the performance of head ultrasound (HUS) and magnetic resonance imaging (MRI) in their ability to detect brain injury and their predictive value for neurodevelopmental outcomes.

METHODS

This was a systematic review based on literature search in three electronic databases (MEDLINE, EMBASE, Cochrane Library) and additional sources for studies on routine brain injury screening in preterm neonates published during 2000-May 2020. Studies were included if they reported on the comparative performance of HUS and MRI in detecting preterm brain injury and/or their predictive value for neurodevelopmental outcomes. Findings from the included studies underwent narrative synthesis.

RESULTS

Forty-six studies were included. In comparison with HUS, MRI detected more anomalies and provided more details on the severity and the extent of preterm brain injury, particularly for white matter injury and cerebellar haemorrhage. Neonatal neuroimaging predicted outcomes with high negative predictive value but relatively low positive predictive value. The prognostic value of neonatal neuroimaging varied according to several factors including modality and timing of imaging, and tools used for grading brain injury.

CONCLUSION

Compared with HUS, MRI offers a better characterisation of preterm brain injury and may enhance the ability to predict neurodevelopmental outcomes.

Automatic Segmentation of Diffuse White Matter Abnormality on T2-weighted Brain MR Images Using Deep Learning in Very Preterm Infants

About 50%-80% of very preterm infants (VPIs) (≤ 32 weeks gestational age) exhibit diffuse white matter abnormality (DWMA) on their MR images at term-equivalent age. It remains unknown if DWMA is associated with developmental impairments, and further study is warranted. To aid in the assessment of DWMA, a deep learning model for DWMA quantification on T2-weighted MR images was developed. This secondary analysis of prospective data was performed with an internal cohort of 98 VPIs (data collected from December 2014 to April 2016) and an external cohort of 28 VPIs (data collected from January 2012 to August 2014) who had already undergone MRI at term-equivalent age. Ground truth DWMA regions were manually annotated by two human experts with the guidance of a prior published semiautomated algorithm. In a twofold cross-validation experiment using the internal cohort of 98 infants, the three-dimensional (3D) ResU-Net model accurately segmented DWMA with a Dice similarity coefficient of 0.907 ± 0.041 (standard deviation) and balanced accuracy of 96.0% ± 2.1, outperforming multiple peer deep learning models. The 3D ResU-Net model that was trained with the whole internal cohort (n = 98) was further tested on an independent external test cohort (n = 28) and achieved a Dice similarity coefficient of 0.877 ± 0.059 and balanced accuracy of 92.3% ± 3.9. The externally validated 3D ResU-Net deep learning model for accurately segmenting DWMA may facilitate the clinical diagnosis of DWMA in VPIs. Supplemental material is available for this article. Keywords: Brain/Brain Stem, Convolutional Neural Network (CNN), MR-Imaging, Pediatrics, Segmentation, Supervised learning © RSNA, 2021.

Diffuse excessive high signal intensity on term equivalent MRI does not predict disability: a systematic review and meta-analysis

OBJECTIVE

To evaluate whether diffuse excessive high signal intensity (DEHSI) on term equivalent age MRI (TEA-MRI) predicts disability in preterm infants.

DESIGN

This is a systematic review and meta-analysis. Medline, EMBASE, Cochrane Library, EMCARE, Google Scholar and MedNar databases were searched in July 2019. Studies comparing developmental outcomes of isolated DEHSI on TEA-MRI versus normal TEA-MRI were included. Two reviewers independently extracted data and assessed the risk of bias. Meta-analysis was undertaken where data were available in a format suitable for pooling.

MAIN OUTCOME MEASURES

Neurodevelopmental outcomes ≥1 year of corrected age based on validated tools.

RESULTS

A total of 15 studies (n=1832) were included, of which data from 9 studies were available for meta-analysis. The pooled estimate (n=7) for sensitivity of DEHSI in predicting cognitive/mental disability was 0.58 (95% CI 0.34 to 0.79) and for specificity was 0.46 (95% CI 0.20 to 0.74). The summary area under the receiver operating characteristics (ROC) curve was low at 0.54 (CI 0.50 to 0.58). A pooled diagnostic OR (DOR) of 1 indicated that DEHSI does not discriminate preterm infants with and without mental disability. The pooled estimate (n=8) for sensitivity of DEHSI in predicting cerebral palsy (CP) was 0.57 (95% CI 0.37 to 0.75) and for specificity was 0.41 (95% CI 0.24 to 0.62). The summary area under the ROC curve was low at 0.51 (CI 0.46 to 0.55). A pooled DOR of 1 indicated that DEHSI does not discriminate between preterm infants with and without CP.

CONCLUSIONS

DEHSI on TEA-MRI did not predict future development of cognitive/mental disabilities or CP.

PROSPERO REGISTRATION NUMBER

CRD42019130576.

Automated brain MRI metrics in the EPIRMEX cohort of preterm newborns: Correlation with the neurodevelopmental outcome at 2 years

PURPOSE

The purpose of this study was to identify in the EPIRMEX cohort the correlations between MRI brain metrics, including diffuse excessive high signal intensities (DEHSI) obtained with an automated quantitative method and neurodevelopmental outcomes at 2 years.

MATERIALS AND METHODS

A total of 390 very preterm infants (gestational age at birth≤32 weeks) who underwent brain MRI at term equivalent age at 1.5T (n=338) or 3T (n=52) were prospectively included. Using a validated algorithm, automated metrics of the main brain surfaces (cortical and deep gray matter, white matter, cerebrospinal fluid) and DEHSI with three thresholds were obtained. Linear adjust regressions were performed to assess the correlation between brain metrics with the ages and stages questionnaire (ASQ) score at 2 years.

RESULTS

Basal ganglia and thalami, cortex and white matter surfaces positively and significantly correlated with the global ASQ score. For all ASQ sub-domains, basal ganglia and thalami surfaces significantly correlated with the scores. DEHSI was present in 289 premature newborns (74%) without any correlation with the ASQ score. Metrics of DEHSI were greater at 3T than at 1.5T.

CONCLUSION

Brain MRI metrics obtained in our multicentric cohort correlate with the neurodevelopmental outcome at 2 years of age. The quantitative detection of DEHSI is not predictive of adverse outcomes. Our automated algorithm might easily provide useful predictive information in daily practice.

Novel diffuse white matter abnormality biomarker at term-equivalent age enhances prediction of long-term motor development in very preterm children

Our objective was to evaluate the independent prognostic value of a novel MRI biomarker-objectively diagnosed diffuse white matter abnormality volume (DWMA; diffuse excessive high signal intensity)-for prediction of motor outcomes in very preterm infants. We prospectively enrolled a geographically-based cohort of very preterm infants without severe brain injury and born before 32 weeks gestational age. Structural brain MRI was obtained at term-equivalent age and DWMA volume was objectively quantified using a published validated algorithm. These results were compared with visually classified DWMA. We used multivariable linear regression to assess the value of DWMA volume, independent of known predictors, to predict motor development as assessed using the Bayley Scales of Infant & Toddler Development, Third Edition at 3 years of age. The mean (SD) gestational age of the cohort was 28.3 (2.4) weeks. In multivariable analyses, controlling for gestational age, sex, and abnormality on structural MRI, DWMA volume was an independent prognostic biomarker of Bayley Motor scores ([Formula: see text]= -12.59 [95% CI -18.70, -6.48] R² = 0.41). Conversely, visually classified DWMA was not predictive of motor development. In conclusion, objectively quantified DWMA is an independent prognostic biomarker of long-term motor development in very preterm infants and warrants further study.

Antecedents of Objectively Diagnosed Diffuse White Matter Abnormality in Very Preterm Infants

BACKGROUND

Diffuse white matter abnormality (diffuse excessive high signal intensity) is the most common finding on structural brain magnetic resonance imaging (MRI) at term-equivalent age in very preterm infants. Yet, there remains a large gap in our understanding of the etiology of diffuse white matter abnormality. Our objective was to evaluate perinatal and neonatal inflammation-associated antecedents of diffuse white matter abnormality on MRI.

METHODS

We prospectively enrolled 110 very preterm infants born at ≤31 weeks gestational age and collected data on multiple perinatal/neonatal exposures, especially inflammation initiating-illnesses. We performed structural MRI at term-equivalent age and quantified the volume of diffuse white matter abnormality objectively. Multivariable regression was used to identify clinical antecedents of diffuse white matter abnormality.

RESULTS

The mean (S.D.) birth gestational age of the final study sample of 98 very preterm infants was 28.3 (2.5) weeks. Multiple inflammation initiating-illnesses were associated with diffuse white matter abnormality in univariate analyses. In multivariable linear regression analyses controlling for gestational age, severe retinopathy of prematurity (P < 0.001) and bronchopulmonary dysplasia (P = 0.006) were independent risk factors, whereas maternal treatment with 17-hydroxyprogesterone (P < 0.001) was protective of later development of objectively quantified diffuse white matter abnormality.

CONCLUSIONS

We identified several perinatal and neonatal antecedent clinical factors associated with diffuse white matter abnormality. Although we found some support for inflammation as a common underlying mechanism, larger studies are needed to validate inflammation as a potential common pathway to the development of diffuse white matter abnormality in very preterm infants.

Objectively Diagnosed Diffuse White Matter Abnormality at Term Is an Independent Predictor of Cognitive and Language Outcomes in Infants Born Very Preterm

OBJECTIVE

To externally validate the independent value of objectively diagnosed diffuse white matter abnormality (DWMA; also known as diffuse excessive high signal intensity) volume to predict neurodevelopmental outcomes in very preterm infants (≤31 weeks of gestational age).

STUDY DESIGN

A prospective, multicenter, regional population-based cohort study in 98 very preterm infants without severe brain injury on magnetic resonance imaging (MRI). DWMA volume was diagnosed objectively on structural MRI at term-equivalent age using our published algorithm. Multivariable linear regression was used to assess the value of DWMA volume to predict cognitive and language scores on the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) at 2 years corrected age.

RESULTS

Of the infants who returned for follow-up (n = 74), the mean (SD) gestational age was 28.2 (2.4) weeks, and 42 (56.8%) were boys. In bivariable analyses, DWMA volume was a significant predictor of Bayley-III cognitive and language scores. In multivariable analyses, controlling for known predictors of Bayley-III scores (ie, socioeconomic status, gestational age, sex, and global brain abnormality score), DWMA volume remained a significant predictor of cognitive (P < .001) and language (P = .04) scores at 2 years. When dichotomized, objectively diagnosed severe DWMA was a significant predictor of cognitive and language impairments, whereas visual qualitative diagnosis of DWMA was a poor predictor.

CONCLUSIONS

In this multicenter, prospective cohort study, we externally validated our previous findings that objectively diagnosed DWMA is an independent predictor of cognitive and language development in very preterm infants. We also demonstrated again that visually-diagnosed DWMA is not predictive of neurodevelopmental outcomes.

White Matter Injury and Structural Anomalies in Infants with Prenatal Opioid Exposure

Previous studies have not found structural injury or brain malformations in infants and children with prenatal opioid exposure. As part of an ongoing study evaluating neuroimaging in infants with prenatal opioid exposure, we reviewed structural brain MR imaging in 20 term infants with prenatal opioid exposure and 20 term controls at 4-8 weeks of age. We found that 8 of the 20 opioid-exposed infants had punctate white matter lesions or white matter signal abnormality on structural MR imaging, and 2 of the opioid-exposed infants had a septopreoptic fusion anomaly. No controls had white matter injury or structural malformations. Our findings underscore the importance of clinical neurodevelopmental follow-up and the need for more comprehensive imaging and long-term outcomes research following prenatal opioid exposure.

Detection of occult abnormalities in the deep gray matter nuclei of neonates with punctate white matter lesions by magnetic resonance spectroscopy

PURPOSE

Punctate white matter lesions (PWML) are common in preterm neonates and have also been reported in the full term. While most studies focus on white matter abnormalities, gray matter (GM) alterations are generally ignored due to the lack of abnormalities on conventional MRI. This study aims to investigate whether magnetic resonance spectroscopy is a sensitive and practical method to detect occult alterations of deep GM nuclei in these neonates.

METHODS

Neonates with PWML and controls with no MRI abnormalities were retrospectively studied. Apparent diffusion coefficient values and metabolic ratios (Cho/Cr, NAA/Cho, and NAA/Cr) in the lenticular nucleus and the thalamus were compared between the PWML and control groups.

RESULTS

Forty-two neonates with PWML (grades I, II, and III contained 14, 21, and 7 subjects, respectively) and 50 controls were enrolled. Apparent diffusion coefficient values in the lenticular nucleus and the thalamus were not significantly different between the PWML and the control groups. The NAA/Cho ratio was significantly lower in the PWML group than in the control group in both regions, whereas a lower NAA/Cr ratio was only observed in the thalamus. Significantly lower ratios of NAA/Cho in both regions and NAA/Cr in the thalamus were detected in the grade II and III subgroup, whereas the thalamic NAA/Cho ratio was decreased in the grade I group compared with controls.

CONCLUSIONS

Magnetic resonance spectroscopy is a sensitive method for detecting the occult deep GM abnormalities for the study cohort of neonates with PWML when compared with subjects without PWML.

A multi-view pyramid network for skull stripping on neonatal T1-weighted MRI

Skull stripping or brain extraction on magnetic resonance imaging is a crucial step for structure analyses. In spite of good performances of conventional methods on adult brains, the skull stripping for T1-weighted imaging (T1WI) images on the neonatal brain remains a challenge because of the low image contrast. Therefore, this paper proposes a multi-view pyramid skull stripping network (PSSNet) for neonatal T1WI. To achieve superior skull stripping performance, the conventional pyramid scene parsing network was modified through (1) adding the spatial information of raw feature maps by squeezing the channel information during the feature extraction; (2) increasing the receptive field and adding boundary repair block instead of direct up-sampling; (3) obtaining the final mask through a fusion module on multi-view 2D slices. The 3D skull stripping problem was decomposed into multi-view 2D segmentation tasks to improve the efficiency. We enrolled T1WI images of 70 neonates from the local hospital and 7 infants from the publicly available dataset NeuroBrainS12 (MICCAI 2012). Images of 51 and 26 subjects were used for model training and validation. We compared the proposed method with 7 commonly used methods by using the Dice ratio, sensitivity, specificity, and efficiency. The proposed multi-view PSSNet with the highest Dice ratio (95.44-97.33%) was superior to other methods. Meanwhile, the sensitivity (93.19-97.02%), specificity (97.52-99.68%), and efficiency (8.59-9.30 s per subject) of the proposed method were comparable with the state-of-the-art method. In conclusion, the proposed skull stripping network was robust on neonatal T1WI datasets and feasible in clinical applications.

Quantitative Analysis of Punctate White Matter Lesions in Neonates Using Quantitative Susceptibility Mapping and R2* Relaxation

BACKGROUND AND PURPOSE

It is difficult to distinguish punctate white matter lesions from focal hemorrhagic lesions in neonates on conventional MR imaging because both kinds of lesions show increased signal intensity on T1-weighted images and, frequently, decreased signal intensity on T2-weighted images. Our aim was to distinguish punctate white matter lesions and focal hemorrhagic lesions using quantitative measures.

MATERIALS AND METHODS

In the current study, we acquired multiecho gradient recalled-echo MR imaging data from 24 neonates with hypoxic-ischemic encephalopathy and postprocessed them as R2* relaxation maps and quantitative susceptibility maps. Seven subjects who were found to have multifocal punctate white matter lesions and/or focal hemorrhagic lesions on R2* maps were included (mean gestational age at birth, 33 ± 4.28 weeks; mean gestational age at scanning, 38 ± 2 weeks). Manually drawing ROIs on R2* maps, we measured R2* and magnetic susceptibility values of the lesions, along with white matter regions within the corpus callosum as healthy comparison tissue.

RESULTS

R2* and magnetic susceptibility values were both found to easily distinguish punctate white matter lesions, focal hemorrhagic lesions, and healthy white matter tissue from each other (P < .05), with a large Hedge g. R2* and magnetic susceptibility values were significantly increased in focal hemorrhagic lesions compared with punctate white matter lesions and healthy white matter tissue. Punctate white matter lesions were also found to have significantly increased values over healthy white matter tissue.

CONCLUSIONS

R2* and quantitative susceptibility maps can be used to help clinicians distinguish and measure focal hemorrhages, punctate white matter lesions, and healthy white matter tissue.

Objective and Automated Detection of Diffuse White Matter Abnormality in Preterm Infants Using Deep Convolutional Neural Networks

Diffuse white matter abnormality (DWMA), or diffuse excessive high signal intensity is observed in 50-80% of very preterm infants at term-equivalent age. It is subjectively defined as higher than normal signal intensity in periventricular and subcortical white matter in comparison to normal unmyelinated white matter on T2-weighted MRI images. Despite the well-documented presence of DWMA, it remains debatable whether DWMA represents pathological tissue injury or a transient developmental phenomenon. Manual tracing of DWMA exhibits poor reliability and reproducibility and unduly increases image processing time. Thus, objective and ideally automatic assessment is critical to accurately elucidate the biologic nature of DWMA. We propose a deep learning approach to automatically identify DWMA regions on T2-weighted MRI images. Specifically, we formulated DWMA detection as an image voxel classification task; that is, the voxels on T2-weighted images are treated as samples and exclusively assigned as DWMA or normal white matter voxel classes. To utilize the spatial information of individual voxels, small image patches centered on the given voxels are retrieved. A deep convolutional neural networks (CNN) model was developed to differentiate DWMA and normal voxels. We tested our deep CNN in multiple validation experiments. First, we examined DWMA detection accuracy of our CNN model using computer simulations. This was followed by in vivo assessments in a cohort of very preterm infants (N = 95) using cross-validation and holdout validation. Finally, we tested our approach on an independent preterm cohort (N = 28) to externally validate our model. Our deep CNN model achieved Dice similarity index values ranging from 0.85 to 0.99 for DWMA detection in the aforementioned validation experiments. Our proposed deep CNN model exhibited significantly better performance than other popular machine learning models. We present an objective and automated approach for accurately identifying DWMA that may facilitate the clinical diagnosis of DWMA in very preterm infants.

Pattern of intracranial findings detected on magnetic resonance imaging in surviving infants born before 29 weeks of gestation

Despite the positive survival trend in infants born prematurely, the risk for development of intracranial lesions has remained unchanged. However, there are limitations to our understanding of the pattern of the magnetic resonance imaging (MRI) -detected brain pathology in the preterm infants surviving to discharge. The present study outlines the type of intracranial lesions and factors allied with the neonatal brain hemorrhage (NBH) and white matter injury (WMI) seen on MRI at term-equivalent age or close to discharge in infants born before 29 weeks of gestation. We obtained demographic and clinical data, and reports of serial cranial ultrasound (CUS) performed during first month of life and qualitative MRI at term-equivalent age or close to discharge. Statistical comparison was conducted with respect to the MRI results that were classified as normal, WMI, and NBH using univariate and logistic regression analysis. One hundred and ninety three infants with MRI at term-equivalent age or close to discharge were included in final analysis. They were less mature and had a higher prevalence of pathological findings on CUS as compared with 249 other survivors born with gestational ages less than 29 weeks during the assigned study period. MRI was normal in 72.5% [95% Confidence Interval (95% CI 65.9%-78.4%)], showed WMI in 9.8% (95%CI 6.4%-14.9%) and NBH in 17.6% (95%CI 12.9–23.6) of the studied infants. Intracranial hemorrhages had also been reported in 42.2% of the infants with WMI. Except for moderate agreement with prior CUS results, no other factors were associated with the MRI detected pathological findings. In general, the likelihood for detection of WMI and NBH on MRI at term-equivalent age or close to discharge was reduced by approximately 80% and 70%, respectively if the serial CUS had not shown any abnormalities during the first month of life.

Prediction of adverse motor outcome for neonates with punctate white matter lesions by MRI images using radiomics strategy: protocol for a prospective cohort multicentre study

INTRODUCTION

Punctate white matter lesions (PWML) are prevalent white matter disease in preterm neonates, and may cause motor disorders and even cerebral palsy. However, precise individual-based diagnosis of lesions that result in an adverse motor outcome remains unclear, and an effective method is urgently needed to guide clinical diagnosis and treatment. Advanced radiomics for multiple modalities data can provide a possible look for biomarkers and determine prognosis quantitatively. The study aims to develop and validate a model for prediction of adverse motor outcomes at a corrected age (CA) of 24 months in neonates with PWML.

METHODS AND ANALYSIS

A prospective cohort multicentre study will be conducted in 11 Chinese hospitals. A total of 394 neonates with PWML confirmed by MRI will undergo a clinical assessment (modified Neonatal Behavioural Assessment Scale). At a CA of 18 months, the motor function will be assessed by Bayley Scales of Infant and Toddler Development-III (Bayley-III). Mild-to-severe motor impairments will be confirmed using the Bayley-III and Gross Motor Function Classification System at a CA of 24 months. During the data collection, the perinatal and clinical information will also be recorded. According to the radiomics strategy, the extracted imaging features and clinical information will be combined for exploratory analysis. After using multiple-modelling methodology, the accuracy, sensitivity and specificity will be computed. Internal and external validations will be used to evaluate the performance of the radiomics model.

ETHICS AND DISSEMINATION

This study has been approved by the institutional review board of The First Affiliated Hospital of Xi'an Jiaotong University (XJTU1AF2015LSK-172). All parents of eligible participants will be provided with a detailed explanation of the study and written consent will be obtained. The results of this study will be published in peer-reviewed journals and presented at local, national and international conferences.

TRIAL REGISTRATION NUMBER

NCT02637817; Pre-results.

Thirteen-Year Outcomes in Very Preterm Children Associated with Diffuse Excessive High Signal Intensity on Neonatal Magnetic Resonance Imaging

OBJECTIVE

To investigate the association between white matter diffuse excessive high signal intensity (DEHSI) on neonatal magnetic resonance imaging in very preterm infants and neurobehavioral outcomes at the age of 13 years.

STUDY DESIGN

Magnetic resonance images of very preterm children (<30 weeks gestational age or <1250 g birth weight) were evaluated at term-equivalent age with DEHSI classified into 5 grades. Additionally, visibility of the posterior periventricular crossroads was assessed. General intelligence, memory, attention, executive function, motor abilities, and behavior were examined in 125 children at age 13 years and related to DEHSI grades using linear regression.

RESULTS

DEHSI was detected in 93% of infants; 21% grade 1, 22% grade 2, 32% grade 3, and 18% grade 4. Neurobehavioral outcomes were similar for all DEHSI groups. There was weak evidence that higher DEHSI grades related to higher verbal IQ and attention and that lower DEHSI grades related to better planning ability. Adjustment for gestational age, birth weight standard score, and sex further weakened these effects. Only 12 children had invisible posterior crossroads and showed slightly poorer outcomes at 13 years of age.

CONCLUSIONS

There was little evidence that neonatal DEHSI serves as a sensitive biomarker for later impairment. Further investigation on the importance of invisible posterior periventricular crossroads in larger samples is needed.

The challenge of cerebral magnetic resonance imaging in neonates: A new method using mathematical morphology for the segmentation of structures including diffuse excessive high signal intensities

Preterm birth is a multifactorial condition associated with increased morbidity and mortality. Diffuse excessive high signal intensity (DEHSI) has been recently described on T2-weighted MR sequences in this population and thought to be associated with neuropathologies. To date, no robust and reproducible method to assess the presence of white matter hyperintensities has been developed, perhaps explaining the current controversy over their prognostic value. The aim of this paper is to propose a new semi-automated framework to detect DEHSI on neonatal brain MR images having a particular pattern due to the physiological lack of complete myelination of the white matter. A novel method for semi- automatic segmentation of neonatal brain structures and DEHSI, based on mathematical morphology and on max-tree representations of the images is thus described. It is a mandatory first step to identify and clinically assess homogeneous cohorts of neonates for DEHSI and/or volume of any other segmented structures. Implemented in a user-friendly interface, the method makes it straightforward to select relevant markers of structures to be segmented, and if needed, apply eventually manual corrections. This method responds to the increasing need for providing medical experts with semi-automatic tools for image analysis, and overcomes the limitations of visual analysis alone, prone to subjectivity and variability. Experimental results demonstrate that the method is accurate, with excellent reproducibility and with very few manual corrections needed. Although the method was intended initially for images acquired at 1.5T, which corresponds to the usual clinical practice, preliminary results on images acquired at 3T suggest that the proposed approach can be generalized.

Neurodevelopmental outcome in very preterm and very-low-birthweight infants born over the past decade: a meta-analytic review

AIM

The purpose of this systematic review was to provide an up-to-date global overview of the separate prevalences of motor and cognitive delays and cerebral palsy (CP) in very preterm (VPT) and very-low-birthweight (VLBW) infants.

METHOD

A comprehensive search was conducted across four databases. Cohort studies reporting the prevalence of CP and motor or cognitive outcome from 18 months corrected age until 6 years of VPT or VLBW infants born after 2006 were included. Pooled prevalences were calculated with random-effects models.

RESULTS

Thirty studies were retained, which included a total of 10 293 infants. The pooled prevalence of cognitive and motor delays, evaluated with developmental tests, was estimated at 16.9% (95% confidence interval [CI] 10.4-26.3) and 20.6% (95% CI 13.9-29.4%) respectively. Mild delays were more frequent than moderate-to-severe delays. Pooled prevalence of CP was estimated to be 6.8% (95% CI 5.5-8.4). Decreasing gestational age and birthweight resulted in higher prevalences. Lower pooled prevalences were found with the Third Edition of the Bayley Scales of Infant Development than with the Second Edition.

INTERPRETATION

Even though neonatal intensive care has improved over recent decades, there is still a wide range of neurodevelopmental disabilities resulting from VPT and VLBW births. However, pooled prevalences of CP have diminished over the years.

WHAT THIS PAPER ADDS

The Bayley Scales of Infant and Toddler Development, Third Edition reported lower pooled prevalences of motor and cognitive delays than the Second Edition. The pooled prevalence of cerebral palsy in infants born extremely preterm was reduced compared with previous meta-analyses.

T2 Relaxometry MRI Predicts Cerebral Palsy in Preterm Infants

BACKGROUND AND PURPOSE

T2-relaxometry brain MR imaging enables objective measurement of brain maturation based on the water-macromolecule ratio in white matter, but the outcome correlation is not established in preterm infants. Our study aimed to predict neurodevelopment with T2-relaxation values of brain MR imaging among preterm infants.

MATERIALS AND METHODS

From January 1, 2012, to May 31, 2015, preterm infants who underwent both T2-relaxometry brain MR imaging and neurodevelopmental follow-up were retrospectively reviewed. T2-relaxation values were measured over the periventricular white matter, including sections through the frontal horns, midbody of the lateral ventricles, and centrum semiovale. Periventricular T2 relaxometry in relation to corrected age was analyzed with restricted cubic spline regression. Prediction of cerebral palsy was examined with the receiver operating characteristic curve.

RESULTS

Thirty-eight preterm infants were enrolled for analysis. Twenty patients (52.6%) had neurodevelopmental abnormalities, including 8 (21%) with developmental delay without cerebral palsy and 12 (31.6%) with cerebral palsy. The periventricular T2-relaxation values in relation to age were curvilinear in preterm infants with normal development, linear in those with developmental delay without cerebral palsy, and flat in those with cerebral palsy. When MR imaging was performed at >1 month corrected age, cerebral palsy could be predicted with T2 relaxometry of the periventricular white matter on sections through the midbody of the lateral ventricles (area under the receiver operating characteristic curve = 0.738; cutoff value of >217.4 with 63.6% sensitivity and 100.0% specificity).

CONCLUSIONS

T2-relaxometry brain MR imaging could provide prognostic prediction of neurodevelopmental outcomes in premature infants. Age-dependent and area-selective interpretation in preterm brains should be emphasized.

Punctate White Matter Lesions Associated With Altered Brain Development And Adverse Motor Outcome In Preterm Infants

Preterm infants who develop neurodevelopmental impairment do not always have recognized abnormalities on cerebral ultrasound, a modality routinely used to assess prognosis. In a high proportion of infants, MRI detects punctate white matter lesions that are not seen on ultrasonography. To determine the relation of punctate lesions to brain development and early neurodevelopmental outcome we used multimodal brain MRI to study a large cohort of preterm infants. Punctate lesions without other focal cerebral or cerebellar lesions were detected at term equivalent age in 123 (24.3%) (59 male) of the 506 infants, predominantly in the centrum semiovale and corona radiata. Infants with lesions had higher gestational age, birth weight, and less chronic lung disease. Punctate lesions showed a dose dependent relation to abnormalities in white matter microstructure, assessed with tract-based spatial statistics, and reduced thalamic volume (p < 0.0001), and predicted unfavourable motor outcome at a median (range) corrected age of 20.2 (18.4–26.3) months with sensitivity (95% confidence intervals) 71 (43–88) and specificity 72 (69–77). Punctate white matter lesions without associated cerebral lesions are common in preterm infants currently not regarded as at highest risk for cerebral injury, and are associated with widespread neuroanatomical abnormalities and adverse early neurodevelopmental outcome.

Regional brain volume reduction and cognitive outcomes in preterm children at low risk at 9 years of age

OBJECTIVE

More information is needed on "low-risk" preterm infants' neurological outcome so that they can be included in follow-up programs. A prospective study was performed to examine the regional brain volume changes compared to term children and to assess the relationship between the regional brain volumes to cognitive outcome of the low-risk preterm children at 9 years of age.

PATIENTS

Subjects comprised 22 preterm children who were determined to be at low risk for neurodevelopmental deficits with a gestational age between 28 and 33 weeks without a major neonatal morbidity in the neonatal period and 24 age-matched term control children term and matched for age, sex, and parental educational and occupational status.

METHODS

Regional volumetric analysis was performed for cerebellum, hippocampus, and corpus callosum area. Cognitive outcomes of both preterm and control subjects were assessed by Weschler Intelligence Scale for Children Revised (Turkish version), and attention and executive functions were assessed by Wisconsin Card Sorting Test and Stroop Test TBAG version.

RESULTS

Low-risk preterm children showed regional brain volume reduction in cerebellum, hippocampus, and corpus callosum area and achieved statistical significance when compared with term control. When the groups were compared for all WISC-R subscale scores, preterm children at low risk had significantly lower scores on information, vocabulary, similarities, arithmetics, picture completion, block design, object assembly, and coding compared to children born at term. Preterm and term groups were compared on the Stroop Test for mistakes and corrections made on each card, the time spent for completing each card, and total mistakes and corrections. In the preterm group, we found a positive correlation between regional volumes with IQ, attention, and executive function scores. Additionally, a significant correlation was found between cerebellar volume and attention and executive function scores in the preterm group.

CONCLUSION

Low-risk preterm children achieve lower scores in neurophysiological tests than children born at term. Preterm birth itself has a significant impact on regional brain volumes and cognitive outcome of children at 9 years of age. It is a risk factor for regional brain volume reductions in preterm children with low risk for neurodevelopmental deficits. The significant interaction between cerebellar volume reduction and executive function and attention may suggest that even in preterm children at low risk can have different trajectories in the growth and development of overall brain structure.

The Impact of Low-Grade Germinal Matrix-Intraventricular Hemorrhage on Neurodevelopmental Outcome of Very Preterm Infants

BACKGROUND

Very preterm infants often show germinal matrix-intraventricular hemorrhage (GMH-IVH) on cranial ultrasound (cUS).

AIM

To determine the impact of low-grade GMH-IVH on early neurodevelopmental outcome in very preterm infants.

METHODS

A retrospective case-control study in very preterm infants with and without low-grade GMH-IVH on cUS. Additional magnetic resonance imaging (MRI) was available in all infants with a gestational age (GA) <28 weeks and high-risk infants >28 weeks. Infants were seen at 2 years' corrected age to assess neurodevelopment.

RESULTS

In total, 136 infants (GA 24-32 weeks) with low-grade GMH-IVH on cUS were matched with 255 controls. Outcome data was available for 342 (87%) infants. Adverse outcome (i.e., cerebral palsy [CP], neurodevelopmental delay) was present in 11 (9%) cases and 20 (9%) controls. No statistically significant differences in outcome were found between cases and controls. Additional MRI was performed in 165/391 infants (42%) and showed additional lesions in 73 (44%) infants that could explain subsequent development of CP in 2 out of 5 infants and epilepsy in 1 of 2 infants.

CONCLUSION

Very preterm infants with low-grade GMH-IVH on cUS have a similar early neurodevelopmental outcome compared with controls. Additional MRI showed mostly subtle abnormalities that were missed with cUS, but these could not explain subsequent development of CP and developmental delay in all infants.

Isolated neonatal MRI punctate white matter lesions in very preterm neonates and quality of life at school age

OBJECTIVE

To study the quality of life at school age of very preterm infants presenting isolated punctate periventricular white matter lesions (IPWL) on late-preterm or term magnetic resonance imaging (MRI).

METHODS

In 1996-2000, 16 of the 131 very preterm neonates explored by MRI were found to have IPWL. At the age of 9-14, 12 children from the IPWL group were compared with 54 children born preterm but with a normal MRI (no lesion). Quality of life (Health Status Classification System Pre School questionnaire), school performance, and motor outcome were investigated.

RESULTS

Overall quality of life did not differ between the groups (classified as perfect in 2/12 of the IPWL vs 20/54 in the no-lesion). The sub-items mobility and dexterity differed significantly between the two groups, with impairment in the IPWL group (p < 0.001 and p < 0.05). This group also displayed higher levels of motor impairment: they began walking later [20(4) vs. 15(3) months), p < 0.01], had higher frequencies of cerebral palsy (6/12 vs. 2/54, p < 0.05), and dyspraxia (4/12 vs. 0/54, p < 0.001). The rate of grade retention did not differ between the groups (3/12 in the IPWL group vs. 17/54 in the no-lesions group) but, as expected, was higher than that of the French general population (17.4%) during the study period.

CONCLUSION

This long-term follow-up study detected no increase in the risk of subsequent cognitive impairment in very preterm infants with IPWL, but suggests that these children may have a significantly higher risk of dyspraxia, and motor impairment.

Neuropathology Associated With Diffuse Excessive High Signal Intensity Abnormalities on Magnetic Resonance Imaging in Very Preterm Infants

BACKGROUND

Diffuse excessive high signal intensity abnormality is the most common finding on term-equivalent age magnetic resonance imaging in extremely preterm infants. Yet its clinical significance remains a matter of debate, in part because of a lack of prior imaging-pathology correlational studies.

PATIENT PRESENTATIONS

We present two 24-week-gestation infants with complicated clinical courses who died at 33 and 46 weeks postmenstrual age with magnetic resonance imaging evidence of diffuse excessive high signal intensity. Two patients with periventricular leukomalacia and two without injury were examined for comparison. Immunohistochemistry characterized the presence of reactive astrocytes, microglia, myelin, and axons. Infants with periventricular leukomalacia demonstrated the typical microscopic necrosis with spheroids, gliosis/microgliosis with reduction in stainable myelin and axons. Infants with diffuse excessive high signal intensity showed vacuolated regions with increased reactive astrocytes and microglia and fewer oligodendroglial cell bodies/processes and dramatic reduction in axon number.

CONCLUSION

These two individuals with diffuse excessive high signal intensity exhibited pathologic characteristics that were overlapping but distinct from those of periventricular leukomalacia.

Advanced neuroimaging and its role in predicting neurodevelopmental outcomes in very preterm infants

Up to 35% of very preterm infants survive with neurodevelopmental impairments (NDI) such as cognitive deficits, cerebral palsy, and attention deficit disorder. Advanced MRI quantitative tools such as brain morphometry, diffusion MRI, magnetic resonance spectroscopy, and functional MRI at term-equivalent age are ideally suited to improve current efforts to predict later development of disabilities. This would facilitate application of targeted early intervention therapies during the first few years of life when neuroplasticity is optimal. A systematic search and review identified 47 published studies of advanced MRI to predict NDI. Diffusion MRI and morphometry studies were the most commonly studied modalities. Despite several limitations, studies clearly showed that brain structural and metabolite biomarkers are promising independent predictors of NDI. Large representative multicenter studies are needed to validate these studies.

A challenging issue: Detection of white matter hyperintensities in neonatal brain MRI

The progress of magnetic resonance imaging (MRI) allows for a precise exploration of the brain of premature infants at term equivalent age. The so-called DEHSI (diffuse excessive high signal intensity) of the white matter of premature brains remains a challenging issue in terms of definition, and thus of interpretation. We propose a semi-automatic detection and quantification method of white matter hyperintensities in MRI relying on morphological operators and max-tree representations, which constitutes a powerful tool to help radiologists to improve their interpretation. Results show better reproducibility and robustness than interactive segmentation.

Differentiating T2 hyperintensity in neonatal white matter by two-compartment model of diffusional kurtosis imaging

In conventional neonatal MRI, the T2 hyperintensity (T2h) in cerebral white matter (WM) at term-equivalent age due to immaturity or impairment is still difficult to identify. To clarify such issue, this study used the metrics derived from a two-compartment WM model of diffusional kurtosis imaging (WM-DKI), including intra-axonal, extra-axonal axial and radial diffusivities (D_a, D_e,// and D_e,⊥), to compare WM differences between the simple T2h and normal control for both preterm and full-term neonates, and between simple T2h and complex T2h with hypoxic-ischemic encephalopathy (HIE). Results indicated that compared with control, the simple T2h showed significantly increased D_e,// and D_e,⊥, but no significant change in D_a in multiple premyelination regions, indicative of expanding extra-axonal diffusion microenvironment; while myelinated regions showed no changes. However, compared with simple T2h, the complex T2h with HIE had decreased D_a, increased D_e,⊥ in both premyelination and myelinated regions, indicative of both intra- and extra-axonal diffusion alterations. While diffusion tensor imaging (DTI) failed to distinguish simple T2h from complex T2h with HIE. In conclusion, superior to DTI-metrics, WM-DKI metrics showed more specificity for WM microstructural changes to distinguish simple T2h from complex T2h with HIE.

Clinical Implications of Diffuse Excessive High Signal Intensity (DEHSI) on Neonatal MRI in School Age Children Born Extremely Preterm

OBJECTIVE

Magnetic resonance imaging (MRI) of the brain carried out during the neonatal period shows that 55-80% of extremely preterm infants display white matter diffuse excessive high signal intensity (DEHSI). Our aim was to study differences in developmental outcome at the age of 6.5 years in children born extremely preterm with and without DEHSI.

STUDY DESIGN

This was a prospective cohort study of 83 children who were born in Stockholm, Sweden, between 2004 and 2007, born at gestational age of < 27 weeks + 0 days and who underwent an MRI scan of their brain at term equivalent age. The outcome measures at 6.5 years included testing 66 children with the modified Touwen neurology examination, the Movement Assessment Battery for Children 2, the Wechsler Intelligence Scale for Children-Fourth Edition, Beery Visual-motor Integration test-Sixth Edition, and the Strengths and Difficulties Questionnaire. Group-wise comparisons were done between children with and without DEHSI using Student t-test, Mann Whitney U test, Chi square test and regression analysis.

RESULTS

DEHSI was detected in 39 (59%) of the 66 children who were assessed at 6.5 years. The presence of DEHSI was not associated with mild neurological dysfunction, scores on M-ABC assessment, cognition, visual-motor integration, or behavior at 6.5 years.

CONCLUSION

The presence of qualitatively defined DEHSI on neonatal MRI did not prove to be a useful predictor of long-term impairment in children born extremely preterm.

Impaired oligodendrocyte maturation in preterm infants: Potential therapeutic targets

Preterm birth is an evolving challenge in neonatal health care. Despite declining mortality rates among extremely premature neonates, morbidity rates remain very high. Currently, perinatal diffuse white matter injury (WMI) is the most commonly observed type of brain injury in preterm infants and has become an important research area. Diffuse WMI is associated with impaired cognitive, sensory and psychological functioning and is increasingly being recognized as a risk factor for autism-spectrum disorders, ADHD, and other psychological disturbances. No treatment options are currently available for diffuse WMI and the underlying pathophysiological mechanisms are far from being completely understood. Preterm birth is associated with maternal inflammation, perinatal infections and disrupted oxygen supply which can affect the cerebral microenvironment by causing activation of microglia, astrogliosis, excitotoxicity, and oxidative stress. This intricate interplay of events negatively influences oligodendrocyte development, causing arrested oligodendrocyte maturation or oligodendrocyte cell death, which ultimately results in myelination failure in the developing white matter. This review discusses the current state in perinatal WMI research, ranging from a clinical perspective to basic molecular pathophysiology. The complex regulation of oligodendrocyte development in healthy and pathological conditions is described, with a specific focus on signaling cascades that may play a role in WMI. Furthermore, emerging concepts in the field of WMI and issues regarding currently available animal models are put forward. Novel insights into the molecular mechanisms underlying impeded oligodendrocyte maturation in diffuse WMI may aid the development of novel treatment options which are desperately needed to improve the quality-of-life of preterm neonates.

Aberrant Executive and Frontoparietal Functional Connectivity in Very Preterm Infants With Diffuse White Matter Abnormalities

BACKGROUND

Diffuse white matter abnormalities are identified in up to 80% of very preterm infants on magnetic resonance imaging at 40 weeks' postmenstrual age. Several studies have observed an association between diffuse white matter abnormalities and cognitive deficits. We hypothesized that very preterm infants (gestational age ≤32 weeks) with diffuse white matter abnormalities will exhibit reduced executive control and frontoparietal functional connectivity compared with infants without diffuse white matter abnormalities measured using resting state functional magnetic resonance imaging at term-equivalent age.

METHODS

We quantified diffuse white matter abnormality volume objectively using an automated segmentation approach and defined diffuse white matter abnormality severity as no-mild (volume ≤50th percentile; N = 13) and moderate-severe (N = 14). Resting state networks of interests were identified using probabilistic independent component analysis. Within network functional connectivity was calculated between the different pair of nodes in a given network using partial correlation coefficients.

RESULTS

We studied 27 very preterm infants born at a mean (standard deviation) gestational age of 26.9 (2.0) weeks and imaged at 39.6 (1.4) weeks' postmenstrual age. Within-network connectivity was significantly reduced in the moderate-severe diffuse white matter abnormalities group than in the no-mild diffuse white matter abnormalities group for the executive control (P < 0.001) and frontoparietal (P = 0.02) networks. As expected, connectivity in three control resting state networks was similar: visual (P = 0.17), motor (P = 0.89), and somatosensory (P = 0.69) networks.

CONCLUSIONS

Very preterm infants with moderate or severe diffuse white matter abnormalities exhibited reduced functional connectivity in important cognitive and attention networks. This aberrant connectivity may be the early life antecedent to the cognitive deficits reported at 2 years of age or later in such infants.

Long-term neurodevelopmental outcome in high-risk newborns in resource-limited settings: a systematic review of the literature

BACKGROUND

Improving outcomes beyond survival for high-risk newborns in resource-limited settings is an emerging challenge. Global estimates demonstrate the scale of this challenge and significant gaps in morbidity outcome data in high mortality contexts. A systematic review was conducted to document the prevalence of neurodevelopmental impairment in high-risk newborns who were followed up into childhood in low- and middle-income countries.

METHODS

High-risk newborns were defined as low, very or extremely low birthweight, preterm infants or those surviving birth asphyxia or serious infections. Electronic databases were searched and articles screened for eligibility. Included articles were appraised according to STROBE criteria. Narrative review was performed and median prevalence of key neurodevelopmental outcomes was calculated where data quality allowed.

RESULTS

6959 articles were identified with sixty included in final review. At follow-up in early childhood, median estimated prevalence (inter-quartile range) of overall neurodevelopmental impairment, cognitive impairment and cerebral palsy were: for survivors of prematurity/very low birthweight 21.4% (11.6-30.8), 16.3% (6.3-29.6) and 11.2% (5.9-16.1), respectively, and for survivors of birth asphyxia 34.6% (25.4-51.5), 11.3% (7.7-11.8) and 22.8% (15.7-31.4), respectively. Only three studies reporting outcomes following newborn serious bacterial infections were identified. There was limited reporting of important outcomes such as vision and hearing impairment. Major challenges with standardised reporting of key exposure and developmental outcome variables and lack of control data were identified.

CONCLUSION

Understanding the limitations of the available data on neurodevelopmental outcome in newborns in resource-limited settings provides clear direction for research and efforts to improve long-term outcome in high-risk newborns in these settings.

Predicting developmental outcomes in premature infants by term equivalent MRI: systematic review and meta-analysis

BACKGROUND

This study aims to determine the prognostic accuracy of term MRI in very preterm born (≤32 weeks) or low-birth-weight (≤1500 g) infants for long-term (>18 months) developmental outcomes.

METHODS

We performed a systematic review searching Central, Medline, Embase, and PsycInfo. Two independent reviewers performed study selection, data extraction, and quality assessment. We documented sensitivity and specificity for three different MRI findings (white matter abnormalities (WMA), brain abnormality (BA), and diffuse excessive high signal intensity (DEHSI)), related to developmental outcomes including cerebral palsy (CP), visual and/or hearing problems, motor, neurocognitive, and behavioral function. Using bivariate meta-analysis, we estimated pooled sensitivity and specificity and plotted summary receiver operating characteristic (sROC) curves for different cut-offs of MRI.

RESULTS

We included 20 papers published between 2000 and 2013. Quality of included studies varied. Pooled sensitivity and specificity values (95 % confidence interval (CI)) for prediction of CP combining the three different MRI findings (using normal/mild vs. moderate/severe cut-off) were 77 % (53 to 91 %) and 79 % (51 to 93 %), respectively. For prediction of motor function, the values were 72 % (52 to 86 %) and 62 % (29 to 87 %), respectively. Prognostic accuracy for visual and/or hearing problems, neurocognitive, and/or behavioral function was poor. sROC curves of the individual MRI findings showed that presence of WMA provided the best prognostic accuracy whereas DEHSI did not show any potential prognostic accuracy.

CONCLUSIONS

This study shows that presence of moderate/severe WMA on MRI around term equivalent age can predict CP and motor function in very preterm or low-birth-weight infants with moderate sensitivity and specificity. Its ability to predict other long-term outcomes such as neurocognitive and behavioral impairments is limited. Also, other white matter related tests as BA and DEHSI demonstrated limited prognostic value.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42013006362.

Neurodevelopmental outcome at 36 months in very low birth weight premature infants with MR diffuse excessive high signal intensity (DEHSI) of cerebral white matter

PURPOSE

To understand the meaning of diffuse excessive high signal intensity (DEHSI) of white matter (WM), a frequently observed finding on MR in VLBW infants at a corrected term age.

METHODS

This is a retrospective study. Qualitative visual assessment of cerebral WM signal intensity on T2WI was performed by two readers on 78 VLBW infants, scanned on a 1.5 T-MRI at term equivalent age. ADC values were then measured in six regions of interest: four in frontal and parietal periventricular and two in parietal subcortical WM. Mean ADC values were then compared with qualitative visual assessment and with mean ADC values obtained ten term healthy babies. Both periventricular and subcortical mean ADC values were correlated with the neurological follow-up, evaluated with the Griffith's mental developmental scale at 36 months.

RESULTS

There was no agreement between the visual qualitative assessment of white matter DEHSI and corresponding ADC values (P values = 0.42 for periventricular WM; P values = 0.18 for subcortical WM). Mean ADC values were higher in preterms than in term babies (P values <0.001). No significant correlation was found between ADC values and the developmental quotient at 36 months (P values >0.05).

CONCLUSIONS

DEHSI in VLBW infants is a MR finding poorly defined with conventional T2 MRI. The presence of T2 hyperintensities weakly correlates with ADC, and ADC values are not associated with the neurological long-term outcome at 3 years, demonstrating that DEHSI should not be considered as a WM disease.

The predictive validity of neonatal MRI for neurodevelopmental outcome in very preterm children

Very preterm children are at a high risk for neurodevelopmental impairments, but there is variability in the pattern and severity of outcome. Neonatal magnetic resonance imaging (MRI) enhances the capacity to detect brain injury and altered brain development and assists in the prediction of high-risk children who warrant surveillance and early intervention. This review describes the application of conventional and advanced MRI with very preterm neonates, specifically focusing on the relationship between neonatal MRI findings and later neurodevelopmental outcome. Research demonstrates that conventional MRI is strongly associated with neurodevelopmental outcome in childhood. Further studies are needed to examine the role of advanced MRI techniques in predicting outcome in very preterm children, but early research findings are promising. In conclusion, neonatal MRI is predictive of later neurodevelopment but is dependent on appropriately trained specialists and should be interpreted in conjunction with other clinical and social information.

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.

Reduced thalamic volume in preterm infants is associated with abnormal white matter metabolism independent of injury

INTRODUCTION

Altered thalamocortical development is hypothesized to be a key substrate underlying neurodevelopmental disabilities in preterm infants. However, the pathogenesis of this abnormality is not well-understood. We combined magnetic resonance spectroscopy of the parietal white matter and morphometric analyses of the thalamus to investigate the association between white matter metabolism and thalamic volume and tested the hypothesis that thalamic volume would be associated with diminished N-acetyl-aspartate (NAA), a measure of neuronal/axonal maturation, independent of white matter injury.

METHODS

Data from 106 preterm infants (mean gestational age at birth: 31.0 weeks ± 4.3; range 23-36 weeks) who underwent MR examinations under clinical indications were included in this study.

RESULTS

Linear regression analyses demonstrated a significant association between parietal white matter NAA concentration and thalamic volume. This effect was above and beyond the effect of white matter injury and age at MRI and remained significant even when preterm infants with punctate white matter lesions (pWMLs) were excluded from the analysis. Furthermore, choline, and among the preterm infants without pWMLs, lactate concentrations were also associated with thalamic volume. Of note, the associations between NAA and choline concentration and thalamic volume remained significant even when the sample was restricted to neonates who were term-equivalent age or older.

CONCLUSION

These observations provide convergent evidence of a neuroimaging phenotype characterized by widespread abnormal thalamocortical development and suggest that the pathogenesis may involve impaired axonal maturation.

Isolated mild white matter signal changes in preterm infants: a regional approach for comparison of cranial ultrasound and MRI findings

OBJECTIVE

To compare echogenicity detected using cranial ultrasound (cUS) and diffuse excessive high signal intensity (DEHSI) detected using magnetic resonance imaging (MRI) by identical region-based scoring criteria in preterm infants. To explore the association between these white matter (WM) signal changes with early neurobehavior.

STUDY DESIGN

Forty-nine pre-selected premature infants with only echogenicity on a first routine cUS1 underwent MRI and a repeated cUS2 at term equivalent age. Echogenicity and DEHSI were graded in various brain areas and diffusivity values were calculated. Neurobehavior was assessed using the Rapid Neonatal Neurobehavioral Assessment Procedure.

RESULT

WM signal changes were significantly higher on cUS1 than cUS2; and higher in MRI than cUS2 in posterior regions. Infants with DEHSI demonstrated reduced tissue integrity. Imaging findings were not correlated with early neurobehavior.

CONCLUSION

Echogenicity and DEHSI likely represent the same phenomenon. Reduction of over-interpretation of WM signal changes may help define criteria for the judicious use of imaging in routine follow-up of premature infants.

Diffuse excessive high signal intensity in low-risk preterm infants at term-equivalent age does not predict outcome at 1 year: a prospective study

INTRODUCTION

The outcome of premature infants with only diffuse excessive high signal intensity (DEHSI) is not clear. We explored the relationship between DEHSI, white matter (WM) diffusion characteristics, perinatal characteristics, and neurobehavioral outcome at 1 year in a homogenous group of preterm infants without major brain abnormalities.

METHODS

Fifty-eight preterm infants, gestational age 29 ± 2.6 weeks, underwent an MRI at term-equivalent age (TEA). Griffiths Mental Developmental Scales, neurological assessment, and Parental Stress Index (PSI) were performed at 1 year corrected age. These measures were compared between preterm infants according to DEHSI classification (none, mild, moderate). Diffusion tensor imaging was used in major WM volumes of interest to objectively measure the degree of WM maturation.

RESULTS

No significant differences were detected in the perinatal risk characteristics, neurobehavioral outcome, and PSI at 1 year between infants with different DEHSI classifications. In infants with DEHSI, increased axial and radial diffusivities were detected in the optic radiations, centrum semiovale, and posterior limb of the internal capsule, indicating less advanced maturation of the WM. Significant correlations were detected between the time interval from birth to MRI and the WM microstructure in infants without DEHSI.

CONCLUSION

DEHSI in premature infants is neither a predictive measure for short-term adverse neurobehavioral outcome nor related to perinatal risk characteristics. Extrauterine exposure time had a differential effect on WM maturational trajectories in infants with DEHSI compared to those without. We suggest DEHSI may represent an alteration in WM maturational characteristics. Further follow-up studies may verify later consequences of DEHSI in premature infants.

Neuroimaging of white matter injury, intraventricular and cerebellar hemorrhage

White matter injury and hemorrhage are common findings in extremely preterm infants. Large hemorrhages and extensive cystic lesions are identified with cranial ultrasound. MRI, which is more sensitive, is especially useful in the identification of small intraventricular hemorrhage; cerebellar hemorrhage; punctate lesion in the white matter and cerebellum; and diffuse, noncystic white matter injury. Imaging sequences such as diffusion-weighted, diffusion tensor, and susceptibility weighted imaging may improve recognition and prediction of outcome. These techniques improve understanding of the underlying pathophysiology of white matter injury and its effects on brain development and neurodevelopmental outcome.

The role of neuroimaging in predicting neurodevelopmental outcomes of preterm neonates

Magnetic resonance imaging (MRI) is a safe and high-resolution neuroimaging modality that is increasingly used in the neonatal population to assess brain injury and its consequences on brain development. It is superior to cranial ultrasound for the definition of patterns of both white and gray matter maturation and injury and therefore has the potential to provide prognostic information on the neurodevelopmental outcomes of the preterm population. Furthermore, the development of sophisticated MRI strategies, including diffusion tensor imaging, resting state functional connectivity, and magnetic resonance spectroscopy, may increase the prognostic value, helping to guide parental counseling and allocate early intervention services.

Atlas-guided quantification of white matter signal abnormalities on term-equivalent age MRI in very preterm infants: findings predict language and cognitive development at two years of age

The developmental significance of the frequently encountered white matter signal abnormality (WMSA) findings on MRI around term-equivalent age (TEA) in very preterm infants, remains in question. The use of conventional qualitative analysis methods is subjective, lacks sufficient reliability for producing accurate and reproducible WMSA diagnosis, and possibly contributes to suboptimal neurodevelopmental outcome prediction. The advantages of quantitative over qualitative diagnostic approaches have been widely acknowledged and demonstrated. The purpose of this study is to objectively and accurately quantify WMSA on TEA T2-weighted MRI in very preterm infants and to assess whether such quantifications predict 2-year language and cognitive developmental outcomes. To this end, we constructed a probabilistic brain atlas, exclusively for very preterm infants to embed tissue distributions (i.e. to encode shapes, locations and geometrical proportion of anatomical structures). Guided with this atlas, we then developed a fully automated method for WMSA detection and quantification using T2-weighted images. Computer simulations and experiments using in vivo very preterm data showed very high detection accuracy. WMSA volume, particularly in the centrum semiovale, on TEA MRI was a significant predictor of standardized language and cognitive scores at 2 years of age. Independent validation of our automated WMSA detection algorithm and school age follow-up are important next steps.

Automatically quantified diffuse excessive high signal intensity on MRI predicts cognitive development in preterm infants

BACKGROUND

Cognitive and language impairments constitute the majority of disabilities observed in preterm infants. It remains unclear if diffuse excessive high signal intensity on magnetic resonance imaging at term represents delayed white matter maturation or pathology.

METHODS

We hypothesized that diffusion tensor imaging-based objectively quantified diffuse excessive high signal intensity measures at term will be strong predictors of cognitive and language development at 2 years in a cohort of 41 extremely low birth weight (≤1000 g) infants. Using an automated probabilistic atlas, mean diffusivity maps were used to objectively segment and quantify diffuse excessive high signal intensity volume and mean, axial, and radial diffusivity measures. Standardized neurodevelopment was assessed at 2 years of age using the Bayley Scales of Infant Development, third edition.

RESULTS

Thirty-six of the 41 infants (88%) had complete developmental data at follow-up. Objectively quantified diffuse excessive high signal intensity volume correlated significantly with cognitive and language scores at 2 years (P < 0.001 for both). The sum values of the three diffusivity measures in detected diffuse excessive high signal intensity regions also correlated significantly with the Bayley scores (r(2) 34.7%; P < 0.001 for each). Infants in the highest quartile for diffuse excessive high signal intensity volumes had scores between 19 and 24 points lower than infants in the lowest quartile (P < 0.01). When diagnosed subjectively by neuroradiologists however, Bayley scores were not significantly lower in infants with extensive diffuse excessive high signal intensity.

CONCLUSIONS

These findings lend further evidence that diffuse excessive high signal intensity is pathologic and that objectively quantified diffusion-based diffuse excessive high signal intensity volume at term is associated with cognitive and language impairments. Our approach could be used for risk stratification and early intervention for such high-risk extremely preterm infants.