Magnetic resonance imaging of the brain in a cohort of extremely preterm infants

Brain MRI findings and their association with visual impairment in young adolescents born very preterm

PURPOSE

Very preterm birth increases risk for neonatal white matter injury, but there is limited data on to what extent this persists into adolescence and how this relates to ophthalmological outcomes. The aim of this study was to assess brain MRI findings in 12-year-old children born very preterm compared to controls and their association with concurrent ophthalmological outcomes.

METHODS

We included 47 children born very preterm and 22 full-term controls (gestational age <32 and >37 weeks, respectively). Brain MRI findings were studied in association with concurrent ophthalmological outcomes at 12-year follow-up.

RESULTS

Evans index (0.27 vs 0.25, p<0.001) and a proposed "posterior ventricle index" (0.47 vs 0.45, p=0.018) were increased in children born very preterm. Higher gestational age associated with larger corpus callosum area (β=10.7, 95%CI 0.59-20.8). Focal white matter lesions were observed in 15 (32%) of very preterm children and in 1 (5%) of full-term controls. Increased posterior ventricle index increased risk for visual acuity ≤1.0 (OR=1.07×1011, 95%CI=7.78-1.48×1021) and contrast sensitivity <0.5 (OR=2.6×1027, 95%CI=1.9×108-3.5×1046). Decreased peritrigonal white matter thickness associated with impaired visual acuity (β=0.04, 95%CI 0.002-0.07).

CONCLUSION

More white matter lesions and evidence of lower white matter volume were found in children born very preterm compared with full-term controls at 12-year follow-up. The association between larger posterior ventricle index and reduced visual acuity and contrast sensitivity suggests disturbances of the posterior visual pathway due to diffuse white matter lesions.

Fetal brain imaging provides valuable information in cCMV infected infants

BACKGROUND

Congenital CMV infection (cCMV) is the most common congenital infection with 10-15% of cases developing symptomatic disease. Early antiviral treatment is of essence when symptomatic disease is suspected. Recently, the use of neonatal imaging has been implicated as a prognostic tool for long term sequalae among asymptomatic newborns at high risk. Even though neonatal MRI is commonly used in neonatal symptomatic cCMV disease, it is less often used in asymptomatic newborns, mainly due to cost, access and difficulty to perform. We have therefore developed an interest in assessing the use of fetal imaging as an alternative. Our primary aim was to compare the fetal and neonatal MRIs in a small cohort 10 asymptomatic neonates with congenital CMV infection.

METHODS

We performed a single-center retrospective cohort study (case-series) on a convenience sample of children born from January 2014 to March 2021 with confirmed congenital CMV infection who had undergone both fetal and neonatal MRIs. We created a checklist of relevant cerebral abnormalities and asked 4 blinded radiologists to assess the MRIs (2 for each, namely fetal and neonatal) and then compared the findings between the fetal and neonatal imaging as well as the concordance in reporting of abnormalities within each category.

FINDINGS

Overall concordance between prenatal and postnatal scans was high (70%). When comparing the two blinded reports for each MRI, we found high levels of concordance: 90% concordance for fetal MRIs and 100% for neonatal MRIs. The most common abnormalities identified in both fetal and neonatal scans were "abnormal white matter hyperintensity" and "subependymal cysts."

INTERPRETATION

Even though this is a small descriptive study, it indicates that fetal MRI could potentially provide us with similar information as neonatal imaging. This study could form the basis for subsequent larger future studies.

Brain structure and function in the fourth decade of life after extremely low birth weight: An MRI and EEG study

OBJECTIVE

To examine potential long-term effects of extremely low birth weight (ELBW; ≤ 1000 g) on adult brain structure, brain function, and cognitive-behavioral performance.

METHODS

A subset of survivors from the prospectively-followed McMaster ELBW Cohort (n = 23, MBW = 816 g) and their peers born at normal birth weight (NBW; ≥ 2500 g; n = 14, MBW = 3361 g) provided T1-weighted magnetic resonance imaging (MRI) brain scans, resting electroencephalographic (EEG) recordings, and behavioral responses to a face-processing task in their early thirties.

RESULTS

Visual discrimination accuracy for human faces, resting EEG alpha power, and long-distance alpha coherence were lower in ELBW survivors than NBW adults, and volumes of white matter hypointensities (WMH) were higher. Across groups, face-processing performance was correlated positively with posterior EEG spectral power and long-distance alpha and theta coherence, and negatively with WMH. The associations between face-processing scores and parietal alpha power and theta coherence were reduced after adjustment for WMH.

CONCLUSIONS

Electrocortical activity, brain functional connectivity, and higher-order processing ability may be negatively affected by WMH burden, which is greater in adults born extremely preterm.

SIGNIFICANCE

Decrements in electrocortical activity and behavioral performance in adult ELBW survivors may be partly explained by increased WMH volumes in this vulnerable population.

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.

An ode to fetal, infant, and toddler neuroimaging: Chronicling early clinical to research applications with MRI, and an introduction to an academic society connecting the field

Fetal, infant, and toddler neuroimaging is commonly thought of as a development of modern times (last two decades). Yet, this field mobilized shortly after the discovery and implementation of MRI technology. Here, we provide a review of the parallel advancements in the fields of fetal, infant, and toddler neuroimaging, noting the shifts from clinical to research use, and the ongoing challenges in this fast-growing field. We chronicle the pioneering science of fetal, infant, and toddler neuroimaging, highlighting the early studies that set the stage for modern advances in imaging during this developmental period, and the large-scale multi-site efforts which ultimately led to the explosion of interest in the field today. Lastly, we consider the growing pains of the community and the need for an academic society that bridges expertise in developmental neuroscience, clinical science, as well as computational and biomedical engineering, to ensure special consideration of the vulnerable mother-offspring dyad (especially during pregnancy), data quality, and image processing tools that are created, rather than adapted, for the young brain.

Neurodevelopmental Outcomes of Very-Low-Birth-Weight Infants without Severe Brain Lesions and Impact of Postnatal Steroid Use: A Single-Center Korean Study

Purpose: We used the Bayley Scales of Infant and Toddler Development (BSID)-III to analyze the incidence and risk factors of developmental delay in very-low-birth-weight infants without severe brain lesions. We further examined the correlation between the cumulative dexamethasone dose and developmental assessment results.Methods: We retrospectively analyzed data of preterm infants (birth weight <1,500 g) admitted to our neonatal intensive care unit between January 2014 to December 2020. The BSID-III scores obtained between the corrected ages of 12 and 24 months and after 24 months were analyzed. Developmental delay was defined as a composite score of <85 for the cognition, language, and motor domains. Univariate and multivariate analyses of developmental delay risk factors and developmental changes from the first to second BSID-III were performed. Correlations between the accumulated dexamethasone dose used for bronchopulmonary dysplasia (BPD) and the first and second test scores were analyzed.Results: Seventy-one and thirty-six infants completed the first and second tests, respectively. In both tests, developmental delay was most commonly observed in the language domain (26.8%, 47.2%). In multivariate analysis, mild BPD was identified as a developmental delay risk factor (P<0.05), whereas prenatal steroid use reduced the developmental delay risk (P<0.05). All domain scores were lower in the second test than in the first test. The cognition and language domain scores in the second test decreased with increasing cumulative dexamethasone doses.Conclusion: Very-low-birth-weight infants typically experience language delay, which can persist as they age.

Ductus Arteriosus of Extremely Preterm Twins is More Resistant to Cyclooxygenase Inhibitors Than Those of Singletons

Symptomatic patent ductus arteriosus (sPDA) is common among preterm infants, and can lead to several complications. This is particularly true for extremely preterm infants, as closure of the ductus arteriosus using cyclooxygenase inhibitors is often difficult. A recent study using a preterm sheep model showed that intimal thickening-required for anatomical closure of the ductus arteriosus-is less developed in twins than in singletons. Therefore, this study primarily aimed to prove that the ductus arteriosus of extremely preterm twins is more resistant to cyclooxygenase inhibitors than those of extremely preterm singletons. Its secondary aim was to assess whether the resistance against cyclooxygenase inhibitors differed according to chorionicity. In this retrospective case-control study, medical records of 162 extremely preterm infants (gestational age < 28 weeks) were reviewed, and the treatment course of sPDA was subsequently compared between singletons (n = 131) and twins (n = 31). The median indomethacin doses for sPDA and the necessity for surgical ligation were significantly higher in twins than in singletons (5 vs 2 [p < 0.001] and 42% vs 21% [p = 0.018], respectively). No significant differences in sPDA treatment, including the number of indomethacin doses and the necessity for surgical ligation, were observed between monochorionic diamniotic and dichorionic diamniotic twins. This study confirms that the ductus arteriosus of extremely preterm twins is more resistant to cyclooxygenase inhibitors than those of singletons. However, there was no significant difference in sPDA treatment by chorionicity.

The dimensions of white matter injury in preterm neonates

White matter injury (WMI) represents a frequent form of parenchymal brain injury in preterm neonates. Several dimensions of WMI are recognized, with distinct neuropathologic features involving a combination of destructive and maturational anomalies. Hypoxia-ischemia is the main mechanism leading to WMI and adverse white matter development, which result from injury to the oligodendrocyte precursor cells. Inflammation might act as a potentiator for WMI. A combination of hypoxia-ischemia and inflammation is frequent in several neonatal comorbidities such as postnatal infections, NEC and bronchopulmonary dysplasia, all known contributors to WMI. White matter injury is an important predictor of adverse neurodevelopmental outcomes. When WMI is detected on neonatal brain imaging, a detailed characterization of the injury (pattern of injury, severity and location) may enhance the ability to predict outcomes. This clinically-oriented review will provide an overview of the pathophysiology and imaging diagnosis of the multiple dimensions of WMI, will explore the association between postnatal complications and WMI, and will provide guidance on the signification of white matter anomalies for motor and cognitive development.

Intracranial Hemorrhage and 2-Year Neurodevelopmental Outcomes in Infants Born Extremely Preterm

OBJECTIVES

To determine the incidence, timing, progression, and risk factors for intracranial hemorrhage (ICH) in infants 24^0/7 to 27^6/7 weeks of gestational age and to characterize the association between ICH and death or neurodevelopmental impairment (NDI) at 2 years of corrected age.

STUDY DESIGN

Infants enrolled in the Preterm Erythropoietin Neuroprotection Trial had serial cranial ultrasound scans performed on day 1, day 7-9, and 36 weeks of postmenstrual age to evaluate ICH. Potential risk factors for development of ICH were examined. Outcomes included death or severe NDI as well as Bayley Scales of Infant and Toddler Development, 3rd Edition, at 2 years of corrected age.

RESULTS

ICH was identified in 38% (n = 339) of 883 enrolled infants. Multiple gestation and cesarean delivery reduced the risk of any ICH on day 1. Risk factors for development of bilateral Grade 2, Grade 3, or Grade 4 ICH at day 7-9 included any ICH at day 1; 2 or more doses of prenatal steroids decreased risk. Bilateral Grade 2, Grade 3, or Grade 4 ICH at 36 weeks were associated with previous ICH at day 7-9. Bilateral Grade 2, any Grade 3, and any Grade 4 ICH at 7-9 days or 36 weeks of postmenstrual age were associated with increased risk of death or severe NDI and lower Bayley Scales of Infant and Toddler Development, 3rd Edition, scores.

CONCLUSIONS

Risk factors for ICH varied by timing of bleed. Bilateral and increasing grade of ICH were associated with death or NDI in infants born extremely preterm.

Neuroimaging at Term Equivalent Age: Is There Value for the Preterm Infant? A Narrative Summary

Advances in neuroimaging of the preterm infant have enhanced the ability to detect brain injury. This added information has been a blessing and a curse. Neuroimaging, particularly with magnetic resonance imaging, has provided greater insight into the patterns of injury and specific vulnerabilities. It has also provided a better understanding of the microscopic and functional impacts of subtle and significant injuries. While the ability to detect injury is important and irresistible, the evidence for how these injuries link to specific long-term outcomes is less clear. In addition, the impact on parents can be profound. This narrative summary will review the history and current state of brain imaging, focusing on magnetic resonance imaging in the preterm population and the current state of the evidence for how these patterns relate to long-term 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.

White matter injury and neurodevelopmental disabilities: A cross-disease (dis)connection

White matter (WM) injury, once known primarily in preterm newborns, is emerging in its non-focal (diffused), non-necrotic form as a critical component of subtle brain injuries in many early-life diseases like prematurity, intrauterine growth restriction, congenital heart defects, and hypoxic-ischemic encephalopathy. While advances in medical techniques have reduced the number of severe outcomes, the incidence of tardive impairments in complex cognitive functions or psychopathology remains high, with lifelong detrimental effects. The importance of WM in coordinating neuronal assemblies firing and neural groups synchronizing within multiple frequency bands through myelination, even mild alterations in WM structure, may interfere with the cognitive performance that increasing social and learning demands would exploit tardively during children growth. This phenomenon may contribute to explaining longitudinally the high incidence of late-appearing impairments that affect children with a history of perinatal insults. Furthermore, WM abnormalities have been highlighted in several neuropsychiatric disorders, such as autism and schizophrenia. In this review, we gather and organize evidence on how diffused WM injuries contribute to neurodevelopmental disorders through different perinatal diseases and insults. An insight into a possible common, cross-disease, mechanism, neuroimaging and monitoring, biomarkers, and neuroprotective strategies will also be presented.

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.

Beyond Anesthesia Toxicity: Anesthetic Considerations to Lessen the Risk of Neonatal Neurological Injury

Infants who undergo surgical procedures in the first few months of life are at a higher risk of death or subsequent neurodevelopmental abnormalities. Although the pathogenesis of these outcomes is multifactorial, an understanding of the nature and pathogenesis of brain injury in these infants may assist the anesthesiologist in consideration of their day-to-day practice to minimize such risks. This review will summarize the main types of brain injury in preterm and term infants and their key pathways. In addition, the review will address key potential pathogenic pathways that may be modifiable including intraoperative hypotension, hypocapnia, hyperoxia or hypoxia, hypoglycemia, and hyperthermia. Each of these conditions may increase the risk of perioperative neurological injury, but their long-term ramifications are unclear.

Preterm white matter injury: ultrasound diagnosis and classification

White matter injury (WMI) is the most frequent form of preterm brain injury. Cranial ultrasound (CUS) remains the preferred modality for initial and sequential neuroimaging in preterm infants, and is reliable for the diagnosis of cystic periventricular leukomalacia. Although magnetic resonance imaging is superior to CUS in detecting the diffuse and more subtle forms of WMI that prevail in very premature infants surviving nowadays, recent improvement in the quality of neonatal CUS imaging has broadened the spectrum of preterm white matter abnormalities that can be detected with this technique. We propose a structured CUS assessment of WMI of prematurity that seeks to account for both cystic and non-cystic changes, as well as signs of white matter loss and impaired brain growth and maturation, at or near term equivalent age. This novel assessment system aims to improve disease description in both routine clinical practice and clinical research. Whether this systematic assessment will improve prediction of outcome in preterm infants with WMI still needs to be evaluated in prospective studies.

Retinopathy of Prematurity and Bronchopulmonary Dysplasia are Independent Antecedents of Cortical Maturational Abnormalities in Very Preterm Infants

Very preterm (VPT) infants are at high-risk for neurodevelopmental impairments, however there are few validated biomarkers at term-equivalent age that accurately measure abnormal brain development and predict future impairments. Our objectives were to quantify and contrast cortical features between full-term and VPT infants at term and to associate two key antecedent risk factors, bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP), with cortical maturational changes in VPT infants. We prospectively enrolled a population-based cohort of 110 VPT infants (gestational age ≤31 weeks) and 51 healthy full-term infants (gestational age 38-42 weeks). Structural brain MRI was performed at term. 94 VPT infants and 46 full-term infants with high-quality T2-weighted MRI were analyzed. As compared to full-term infants, VPT infants exhibited significant global cortical maturational abnormalities, including reduced surface area (-5.9%) and gyrification (-6.7%) and increased curvature (5.9%). In multivariable regression controlled for important covariates, BPD was significantly negatively correlated with lobar and global cortical surface area and ROP was significantly negatively correlated with lobar and global sulcal depth in VPT infants. Our cohort of VPT infants exhibited widespread cortical maturation abnormalities by term-equivalent age that were in part anteceded by two of the most potent neonatal diseases, BPD and ROP.

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.

Goal Setting Deficits at 13 Years in Very Preterm Born Children

OBJECTIVES

Preterm children demonstrate deficits in executive functions including inhibition, working memory, and cognitive flexibility; however, their goal setting abilities (planning, organization, strategic reasoning) remain unclear. This study compared goal setting abilities between very preterm (VP: <30 weeks/<1250 grams) and term born controls during late childhood. Additionally, early risk factors (neonatal brain abnormalities, medical complications, and sex) were examined in relationship to goal setting outcomes within the VP group.

METHODS

Participants included 177 VP and 61 full-term born control children aged 13 years. Goal setting was assessed using several measures of planning, organization, and strategic reasoning. Parents also completed the Behavior Rating Inventory of Executive Function. Regression models were performed to compare groups, with secondary analyses adjusting for potential confounders (sex and social risk), and excluding children with major neurosensory impairment and/or IQ<70. Within the VP group, regression models were performed to examine the relationship between brain abnormalities, medical complications, and sex, on goal setting scores.

RESULTS

The VP group demonstrated a clear pattern of impairment and inefficiency across goal setting measures, consistent with parental report, compared with their full-term born peers. Within the VP group, moderate/severe brain abnormalities on neonatal MRI predicted adverse goal setting outcomes at 13.

CONCLUSIONS

Goal setting difficulties are a significant area of concern in VP children during late childhood. These difficulties are associated with neonatal brain abnormalities, and are likely to have functional consequences academically, socially and vocationally. (JINS, 2018, 24, 372-381).

Annual Research Review: Not just a small adult brain: understanding later neurodevelopment through imaging the neonatal brain

BACKGROUND

There has been a recent proliferation in neuroimaging research focusing on brain development in the prenatal, neonatal and very early childhood brain. Early brain injury and preterm birth are associated with increased risk of neurodevelopmental disorders, indicating the importance of this early period for later outcome.

SCOPE AND METHODOLOGY

Although using a wide range of different methodologies and investigating diverse samples, the common aim of many of these studies has been to both track normative development and investigate deviations in this development to predict behavioural, cognitive and neurological function in childhood. Here we review structural and functional neuroimaging studies investigating the developing brain. We focus on practical and technical complexities of studying this early age range and discuss how neuroimaging techniques have been successfully applied to investigate later neurodevelopmental outcome.

CONCLUSIONS

Neuroimaging markers of later outcome still have surprisingly low predictive power and their specificity to individual neurodevelopmental disorders is still under question. However, the field is still young, and substantial challenges to both acquiring and modeling neonatal data are being met.

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.

Multimodal image analysis of clinical influences on preterm brain development

OBJECTIVE

Premature birth is associated with numerous complex abnormalities of white and gray matter and a high incidence of long-term neurocognitive impairment. An integrated understanding of these abnormalities and their association with clinical events is lacking. The aim of this study was to identify specific patterns of abnormal cerebral development and their antenatal and postnatal antecedents.

METHODS

In a prospective cohort of 449 infants (226 male), we performed a multivariate and data-driven analysis combining multiple imaging modalities. Using canonical correlation analysis, we sought separable multimodal imaging markers associated with specific clinical and environmental factors and correlated to neurodevelopmental outcome at 2 years.

RESULTS

We found five independent patterns of neuroanatomical variation that related to clinical factors including age, prematurity, sex, intrauterine complications, and postnatal adversity. We also confirmed the association between imaging markers of neuroanatomical abnormality and poor cognitive and motor outcomes at 2 years.

INTERPRETATION

This data-driven approach defined novel and clinically relevant imaging markers of cerebral maldevelopment, which offer new insights into the nature of preterm brain injury. Ann Neurol 2017;82:233-246.

The most-cited articles in pediatric imaging: a bibliometric analysis

INTRODUCTION

The number of citations that an article has received reflects its impact on the scientific community. The purpose of our study was to identify and characterize the 51 most-cited articles in pediatric imaging.

EVIDENCE ACQUISITION

Based on the database of Journal Citation Reports, we selected 350 journals that were considered as potential outlets for pediatric imaging articles. The Web of Science search tools were used to identify the most-cited articles relevant to pediatric imaging within the selected journals.

EVIDENCE SYNTHESIS

The 51 most-cited articles in pediatric imaging were published between 1952 and 2011, with 1980-1989 and 2000-2009 producing 15 articles, each. The number of citations ranged from 576-124 and the number of annual citations ranged from 49.05-2.56. The majority of articles were published in pediatric and related journals (N.=26), originated in the USA (N.=23), were original articles (N.=45), used MRI as imaging modality (N.=27), and were concerned with the subspecialty of brain (N.=34). University College London School of Medicine (N.=6) and School of Medicine University of California (N.=4) were the leading institutions and Reynolds EO (N.=7) was the most voluminous author.

CONCLUSIONS

Our study presents a detailed list and an analysis of the most-cited articles in the field of pediatric imaging, which provides an insight into historical developments and allows for recognition of the important advances in this field.

Ultrasound Elastography of the Neonatal Brain: Preliminary Study

OBJECTIVES

To determine the ultrasound elasticity of the brain in neonates METHODS: Strain elastography was performed in 21 healthy neonates (mean gestational age [GA], 34 weeks; range, 28-40 weeks). Elastographic scores were assigned to the following structures on a 5-point color scale (1-5): ventricle, periventricular white matter, caudate, subcortical, cortical gray matter, and subdural space. Three elastographic images were evaluated in each patient, and median elastographic scores were calculated. The scores were compared between regions and were correlated with the corrected GA. Interobserver agreements for assignment of elastographic scores were analyzed.

RESULTS

The ventricle and subdural space showed an elasticity score of 1 in all patients. The cortical gray matter (median, 3.0; first-third quartiles, 2.33-3.33) showed higher elasticity compared to the periventricular white mater (4.0; 3.00-4.00; P < .001), caudate (4.3; 3.67-4.67; P < .001), and subcortical white matter (4.0; 4.00-4.00; P < .001). The caudate showed lower elasticity compared to periventricular white matter (P = .004). The periventricular white matter showed higher elasticity compared to subcortical white matter (P = .009). There was a positive trend between the corrected GA and cortical gray matter elastographic score (γ = 0.376; P = .093). Interobserver agreement was moderate to almost perfect (κ = 0.53-0.89).

CONCLUSIONS

Neonatal intracranial regions showed different elasticity, which could be accessed by strain elastography. These normal findings should prompt future studies investigating the use of ultrasound elastography in the neonatal brain.

Ventricular shape and relative position abnormalities in preterm neonates

Recent neuroimaging findings have highlighted the impact of premature birth on subcortical development and morphological changes in the deep grey nuclei and ventricular system. To help characterize subcortical microstructural changes in preterm neonates, we recently implemented a multivariate tensor-based method (mTBM). This method allows to precisely measure local surface deformation of brain structures in infants. Here, we investigated ventricular abnormalities and their spatial relationships with surrounding subcortical structures in preterm neonates. We performed regional group comparisons on the surface morphometry and relative position of the lateral ventricles between 19 full-term and 17 preterm born neonates at term-equivalent age. Furthermore, a relative pose analysis was used to detect individual differences in translation, rotation, and scale of a given brain structure with respect to an average. Our mTBM results revealed broad areas of alterations on the frontal horn and body of the left ventricle, and narrower areas of differences on the temporal horn of the right ventricle. A significant shift in the rotation of the left ventricle was also found in preterm neonates. Furthermore, we located significant correlations between morphology and pose parameters of the lateral ventricles and that of the putamen and thalamus. These results show that regional abnormalities on the surface and pose of the ventricles are also associated with alterations on the putamen and thalamus. The complementarity of the information provided by the surface and pose analysis may help to identify abnormal white and grey matter growth, hinting toward a pattern of neural and cellular dysmaturation.

Growth of Thalamocortical Fibers to the Somatosensory Cortex in the Human Fetal Brain

Thalamocortical (TH-C) fiber growth begins during the embryonic period and is completed by the third trimester of gestation in humans. Here we determined the timing and trajectories of somatosensory TH-C fibers in the developing human brain. We analyzed the periods of TH-C fiber outgrowth, path-finding, "waiting" in the subplate (SP), target selection, and ingrowth in the cortical plate (CP) using histological sections from post-mortem fetal brain [from 7 to 34 postconceptional weeks (PCW)] that were processed with acetylcholinesterase (AChE) histochemistry and immunohistochemical methods. Images were compared with post mortem diffusion tensor imaging (DTI)-based fiber tractography (code No NO1-HD-4-3368). The results showed TH-C axon outgrowth occurs as early as 7.5 PCW in the ventrolateral part of the thalamic anlage. Between 8 and 9.5 PCW, TH-C axons form massive bundles that traverse the diencephalic-telencephalic boundary. From 9.5 to 11 PCW, thalamocortical axons pass the periventricular area at the pallial-subpallial boundary and enter intermediate zone in radiating fashion. Between 12 and 14 PCW, the TH-C axons, aligned along the fibers from the basal forebrain, continue to grow for a short distance within the deep intermediate zone and enter the deep CP, parallel with SP expansion. Between 14 and 18 PCW, the TH-C interdigitate with callosal fibers, running shortly in the sagittal stratum and spreading through the deep SP ("waiting" phase). From 19 to 22 PCW, TH-C axons accumulate in the superficial SP below the somatosensory cortical area; this occurs 2 weeks earlier than in the frontal and occipital cortices. Between 23 and 24 PCW, AChE-reactive TH-C axons penetrate the CP concomitantly with its initial lamination. Between 25 and 34 PCW, AChE reactivity of the CP exhibits an uneven pattern suggestive of vertical banding, showing a basic 6-layer pattern. In conclusion, human thalamocortical axons show prolonged growth (4 months), and somatosensory fibers precede the ingrowth of fibers destined for frontal and occipital areas. The major features of growing TH-C somatosensory fiber trajectories are fan-like radiation, short runs in the sagittal strata, and interdigitation with the callosal system. These results support our hypothesis that TH-C axons are early factors in SP and CP morphogenesis and synaptogenesis and may regulate cortical somatosensory system maturation.

Surgical Ligation for Patent Ductus Arteriosus in Extremely Premature Infants: Strategy to Reduce their Risk of Neurodevelopmental Impairment

Surgical ligation for patent ductus arteriosus (PDA) in extremely low birth weight infants (ELBWIs) has been shown a possible association with neurodevelopmental impairment (NDI) because of its invasiveness. However, we have undergone surgical ligation for ELBWIs immediately after cyclooxygenase inhibitor failed to close a hemodynamically significant PDA (hsPDA) to maintain proper systemic circulation. We aimed to determine the effect of surgical ligation for hsPDA on NDI in ELBWIs. In enrolled 71 ELBWIs, the clinical parameters, including the developmental quotient (DQ), were collected and compared among three groups that were divided by closure mode: spontaneous closure (n = 11), cyclooxygenase inhibitor therapy (n = 37) and surgical ligation (n = 23). No significant differences in DQ at the age of 36 months among the three groups were found: Median (interquartile range): 92.0 (31.0), 89.0 (22.0) and 92.0 (24.5), respectively. In a comparison between groups of DQ < 70 (n = 15) and DQ ≥ 70 (n = 56), a significant difference was found in the parameters related to prematurity (p < 0.05 for each): gestational age [23.9 (1.70) vs. 25.4 (2.50) weeks], birth weight [595 (183) vs. 714 (192) g], Apgar score < 5 (1 min) (67% vs. 36%), and laser photocoagulation for retinopathy of prematurity (73% vs. 43%), but there was no significant association with hsPDA. Therefore, we propose that surgical ligation for hsPDA in ELBWIs should be immediately carried out for preventing future neurodevelopmental deterioration if the cyclooxygenase inhibitor failed to close hsPDA.

Routine Magnetic Resonance Imaging at Term-Equivalent Age Detects Brain Injury in 25% of a Contemporary Cohort of Very Preterm Infants

Introduction

In recent years, significant investigation has been undertaken by means of magnetic resonance imaging (MRI) in an attempt to identify preterm infants at risk for adverse outcome. The primary objective is to provide a comprehensive characterization of cerebral injury detected by conventional MRI at term-equivalent age in an unselected, consecutive, contemporary cohort of preterm infants born <32 gestational weeks. Secondly, this study aims to identify risk factors for the different injury types in this population.

Methods

Data for all preterm infants born <32 gestational weeks and admitted to Innsbruck Medical University Hospital were prospectively collected (October 2010 to December 2015). Cerebral MRI was evaluated retrospectively using a validated scoring system that incorporates intraventricular haemorrhage (IVH), white matter disease (WMD) and cerebellar haemorrhage (CBH).

Results

300 infants were included in the study. MRI showed 24.7% of all infants to have some form of brain injury. The most common injury type was IVH (16.0%). WMD and CBH were seen in 10.0% and 8.0%. The prevalence of common neonatal risk factors was greater within the group of infants with CBH. In particular indicators for respiratory disease were observed more often: longer ventilation duration, more frequent need for supplemental oxygen at day 28, higher rates of hydrocortisone treatment. Catecholamine treatment was the only neonatal risk factor that was overrepresented in infants with WMD

Discussion

Cerebral MRI at term-equivalent age, as addition to cranial ultrasound, detected brain injury in 25% of preterm survivors. The diagnosis of IVH was already made by neonatal ultrasound in most cases. In contrast, only a minority of the CBH and none of the non-cystic WMD have been detected prior to MRI. Decreasing gestational age and neonatal complications involved with immaturity have been identified as risk factors for CBH, whereas WMD was found in relatively mature infants with circulatory disturbances.

Brain Lesions among Orally Fed and Gastrostomy-Fed Dysphagic Preterm Infants: Can Routine Qualitative or Volumetric Quantitative Magnetic Resonance Imaging Predict Feeding Outcomes?

INTRODUCTION

The usefulness of qualitative or quantitative volumetric magnetic resonance imaging (MRI) in early detection of brain structural changes and prediction of adverse outcomes in neonatal illnesses warrants further investigation. Our aim was to correlate certain brain injuries and the brain volume of feeding-related cortical and subcortical regions with feeding method at discharge among preterm dysphagic infants.

MATERIALS AND METHODS

Using a retrospective observational study design, we examined MRI data among 43 (22 male; born at 31.5 ± 0.8 week gestation) infants who went home on oral feeding or gastrostomy feeding (G-tube). MRI scans were segmented, and volumes of brainstem, cerebellum, cerebrum, basal ganglia, thalamus, and vermis were quantified, and correlations were made with discharge feeding outcomes. Chi-squared tests were used to evaluate MRI findings vs. feeding outcomes. ANCOVA was performed on the regression model to measure the association of maturity and brain volume between groups.

RESULTS

Out of 43 infants, 44% were oral-fed and 56% were G-tube fed at hospital discharge (but not at time of the study). There was no relationship between qualitative brain lesions and feeding outcomes. Volumetric analysis revealed that cerebellum was greater (p < 0.05) in G-tube fed infants, whereas cerebrum volume was greater (p < 0.05) in oral-fed infants. Other brain regions did not show volumetric differences between groups.

CONCLUSION

This study concludes that neither qualitative nor quantitative volumetric MRI findings correlate with feeding outcomes. Understanding the complexity of swallowing and feeding difficulties in infants warrants a comprehensive and in-depth functional neurological assessment.

Working memory in very-low-birthweight children at the age of 11 years

The aim of this study is to investigate the working memory (WM) of very-low-birthweight (VLBW, ≤ 1500 g) children at the age of 11 years using Baddeley's WM model. A regional cohort of 95 VLBW children was assessed for the domains of the WM model (central executive [CE], visuospatial sketchpad [VS], and phonological loop [PL]) using subtests from the Working Memory Test Battery for Children (WMTB-C) and the Wechsler Intelligence Scale for Children - Fourth Edition (WISC-IV). VLBW children were categorized into three groups according to their degree of brain pathology (normal, minor, or major) in neonatal brain magnetic resonance imaging at the term age, and the WM performance was compared between groups to test norms. The structure of the WM model was studied by analyzing correlations among domains. Even VLBW children with normal cognitive development (general ability index ≥ 85) performed worse compared to the test norms (M = 100, SD = 15) on CE (M = 87.64, SD = 20.54, p < .001) and VS (M = 91.65, SD = 11.03, p < .001), but their performance on PL was above the norm (M = 110.79, SD = 13.79, p < .001). VLBW children with major brain pathology performed significantly worse on VS and PL compared to the other groups. The correlations among the WM domains of the VLBW children differ from earlier findings in normative populations. To conclude, the WM of the VLBW children in the study differ-especially in the CE and VS subtest scores-from the normative population irrespective of the degree of brain pathology and level of cognitive development.

Impact of Cerebral Visual Impairments on Motor Skills: Implications for Developmental Coordination Disorders

Cerebral visual impairment (CVI) has become the primary cause of visual impairment and blindness in children in industrialized countries. Its prevalence has increased sharply, due to increased survival rates of children who sustain severe neurological conditions during the perinatal period. Improved diagnosis has probably contributed to this increase. As in adults, the nature and severity of CVI in children relate to the cause, location and extent of damage to the brain. In the present paper, we define CVI and how this impacts on visual function. We then define developmental coordination disorder (DCD) and discuss the link between CVI and DCD. The neuroanatomical correlates and aetiologies of DCD are also presented in relationship with CVI as well as the consequences of perinatal asphyxia (PA) and preterm birth on the occurrence and nature of DCD and CVI. This paper underlines why there are both clinical and theoretical reasons to disentangle CVI and DCD, and to categorize the features with more precision. In order to offer the most appropriate rehabilitation, we propose a systematic and rapid evaluation of visual function in at-risk children who have survived preterm birth or PA whether or not they have been diagnosed with cerebral palsy or DCD.

Regional Specificity of Magnetic Resonance Imaging and Histopathology Following Cerebral Ischemia in Preterm Fetal Sheep

Early and accurate evaluation of the nature and extent of cerebral injury in the preterm infant brain is important for prognostication and decision making in the neonatal intensive care unit. The capability of magnetic resonance imaging (MRI) to define acute ischemic changes in white and gray matter in comparison to contemporaneous histopathology has not been adequately ascertained. The aim of this study is to assess whether postmortem MRI predicts the nature and extent of brain injury in a preterm fetal sheep model of cerebral hypoperfusion. MRI examinations were performed on fetal sheep brains (d99-100 gestation), perfusion fixed 72 hours after an ischemic insult (n = 7) with left-hemispheric placement of a microdialysis probe and compared with sham-occlusion (n = 3) and unoperated-control fetuses (n = 4). Cerebral ischemia was associated with MRI changes including global cerebral injury and diffuse white matter signal abnormality, which corresponded closely with histological damage. However, histological changes in deep structures, including the corona radiata, thalamus, and globus pallidus were not reliably detected on MRI. These findings confirm that in preterm fetal sheep, MRI can accurately assess cortical gray matter and subcortical and periventricular white matter abnormalities 3 days after hypoxic-ischemic injury but appears to have limited sensitivity to detect injury to deep structures.

Excessively High Magnetic Resonance Signal in Preterm Infants and Neuropsychobehavioural Follow-up at 2 Years

The diffuse excessive high-signal intensity (DEHSI) findings in the T2 weighted scans of white matter (WM), besides the corresponding low signal in the T1 weighted images, are usually more evident around the periventricular regions. It is not clear whether the DEHSI should be considered as a diffuse WM injury rather than a sign of delayed maturation of the WM. Eighty nine preterm infants at the full-term equivalent age (FEA) were studied using conventional Magnetic Resonance (MR) imaging of the brain. Based on the MR findings, the infants studied were divided into three groups: the control group presenting normal WM, the DEHSI group and the group with other WM lesions. Ten newborns were not included in the statistical analysis because they presented evidence of precedent germinal matrix hemorrhage (GMH-IVH) which cannot be considered as WM lesions. Seventy nine infants were enrolled in a program of neuropsychobehavioural study follow-up until 24 months of age. Each infant was evaluated for those variables which mostly affect the occurrence of neuropsychomotor disability. In the DEHSI infant group, significantly lower mean pH and mean base excess (BE) values were found in comparison to controls, while the mean birth weight (BW) was significantly higher. No significant difference was observed between the mean 1st minute Apgar Score, mean birth gestational age (GA) and assisted ventilation mean duration of controls and DEHSI groups. Finally, no significant difference between the parameters studied was found by comparing the WM lesion infants group to the DEHSI infants one. Our observations, together with follow-up studies, even up to school age, confirm that DEHSI has a clinical significance and cannot be considered as a simple indicator of delayed WM maturation.

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.

New means to assess neonatal inflammatory brain injury

Preterm infants are especially vulnerable to infection-induced white matter injury, associated with cerebral palsy, cognitive and psychomotor impairment, and other adverse neurological outcomes. The etiology of such lesions is complex and multifactorial. Furthermore, timing and length of exposure to infection also influence neurodevelopmental outcomes. Different mechanisms have been posited to mediate the observed brain injury including microglial activation followed by subsequent release of pro-inflammatory species, glutamate-induced excitotoxicity, and vulnerability of developing oligodendrocytes to cerebral insults. The prevalence of such neurological impairments requires an urgent need for early detection and effective neuroprotective strategies. Accordingly, noninvasive methods of monitoring disease progression and therapy effectiveness are essential. While diagnostic tools using biomarkers from bodily fluids may provide useful information regarding potential risks of developing neurological diseases, the use of magnetic resonance imaging/spectroscopy has emerged as a promising candidate for such purpose. Various pharmacological agents have demonstrated protective effects in the immature brain in animal models; however, few studies have progressed to clinical trials with promising results.

Developmental synergy between thalamic structure and interhemispheric connectivity in the visual system of preterm infants

Thalamic structural co-variation with cortical regions has been demonstrated in preterm infants, but its relationship to cortical function and severity of non-cystic white matter injury (non-cystic WMI) is unclear. The relationship between thalamic morphology and both cortical network synchronization and cortical structural connectivity has not been established. We tested the hypothesis that in preterm neonates, thalamic volume would correlate with primary cortical visual function and microstructural integrity of cortico-cortical visual association pathways. A total of 80 term-equivalent preterm and 44 term-born infants underwent high-resolution structural imaging coupled with visual functional magnetic resonance imaging or diffusion tensor imaging. There was a strong correlation between thalamic volume and primary visual cortical activation in preterms with non-cystic WMI (r = 0.81, p-value = 0.001). Thalamic volume also correlated strongly with interhemispheric cortico-cortical connectivity (splenium) in preterm neonates with a relatively higher severity of non-cystic WMI (p-value < 0.001). In contrast, there was lower correlation between thalamic volume and intrahemispheric cortico-cortical connectivity, including the inferior longitudinal fasciculus and inferior frontal orbital fasciculus. This study shows distinct temporal overlap in the disruption of thalamo-cortical and interhemispheric cortico-cortical connectivity in preterm infants suggesting developmental synergy between thalamic morphology and the emergence of cortical networks in the last trimester.

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.