Validation of an MRI Brain Injury and Growth Scoring System in Very Preterm Infants Scanned at 29- to 35-Week Postmenstrual Age

Brain MRI Injury Patterns across Gestational Age among Preterm Infants with Perinatal Asphyxia

INTRODUCTION

Brain injury patterns of preterm infants with perinatal asphyxia (PA) are underreported. We aimed to explore brain magnetic resonance imaging (MRI) findings and associated neurodevelopmental outcomes in these newborns.

METHODS

Retrospective multicenter study included infants with gestational age (GA) 24.0-36.0 weeks and PA, defined as ≥2 of the following: (1) umbilical cord pH ≤7.0, (2) 5-min Apgar score ≤5, and (3) fetal distress or systemic effects of PA. Findings were compared between GA <28.0 (group 1), 28.0-31.9 (group 2), and 32.0-36.0 weeks (group 3). Early MRI (<36 weeks postmenstrual age or <10 postnatal days) was categorized according to predominant injury pattern, and MRI around term-equivalent age (TEA, 36.0-44.0 weeks and ≥10 postnatal days) using the Kidokoro score. Adverse outcomes included death, cerebral palsy, epilepsy, severe hearing/visual impairment, or neurodevelopment <-1 SD at 18-24 months corrected age.

RESULTS

One hundred nineteen infants with early MRI (n = 94) and/or MRI around TEA (n = 66) were included. Early MRI showed predominantly hemorrhagic injury in groups 1 (56%) and 2 (45%), and white matter (WM)/watershed injury in group 3 (43%). Around TEA, WM scores were highest in groups 2 and 3. Deep gray matter (DGM) (aOR 15.0, 95% CI: 3.8-58.9) and hemorrhagic injury on early MRI (aOR 2.5, 95% CI: 1.3-4.6) and Kidokoro WM (aOR 1.3, 95% CI: 1.0-1.6) and DGM sub-scores (aOR 4.8, 95% CI: 1.1-21.7) around TEA were associated with adverse neurodevelopmental outcomes.

CONCLUSION

The brain injury patterns following PA in preterm infants differ across GA. Particularly DGM abnormalities are associated with adverse neurodevelopmental outcomes.

Hypertensive Disorders of Pregnancy and Risk of Early Brain Abnormalities on Magnetic Resonance Imaging at Term among Infants Born at ≤32 Weeks' Gestational Age

OBJECTIVE

To evaluate the proximal effects of hypertensive disorders of pregnancy (HDP) on a validated measure of brain abnormalities in infants born at ≤32 weeks' gestational age (GA) using magnetic resonance imaging at term-equivalent age.

STUDY DESIGN

In a multisite prospective cohort study, 395 infants born at ≤32 weeks' GA, underwent 3T magnetic resonance imaging scan between 39 and 44 weeks' postmenstrual age. A single neuroradiologist, blinded to clinical history, evaluated the standardized Kidokoro global brain abnormality score as the primary outcome. We classified infants as HDP-exposed by maternal diagnosis of chronic hypertension, gestational hypertension, pre-eclampsia, or eclampsia. Linear regression analysis identified the independent effects of HDP on infant brain abnormalities, adjusting for histologic chorioamnionitis, maternal smoking, antenatal steroids, magnesium sulfate, and infant sex. Mediation analyses quantified the indirect effect of HDP mediated via impaired intrauterine growth and prematurity and remaining direct effects on brain abnormalities.

RESULTS

A total of 170/395 infants (43%) were HDP-exposed. Adjusted multivariable analyses revealed HDP-exposed infants had 27% (95% CI 5%-53%) higher brain abnormality scores than those without HDP exposure (P = .02), primarily driven by increased white matter injury/abnormality scores (P = .01). Mediation analyses showed HDP-induced impaired intrauterine growth significantly (P = .02) contributed to brain abnormality scores (22% of the total effect).

CONCLUSIONS

Maternal hypertension independently increased the risk for early brain injury and/or maturational delays in infants born at ≤32 weeks' GA with an indirect effect of 22% resulting from impaired intrauterine growth. Enhanced prevention/treatment of maternal hypertension may mitigate the risk of infant brain abnormalities and potential neurodevelopmental impairments.

Extremely Preterm Infants with a Near-total Absence of Cerebellum: Usefulness of Quantitative Magnetic Resonance in Predicting the Motor Outcome

This study aims to evaluate in extremely premature infants the severity of brain structural injury causing total absence or near-total absence of cerebellar hemispheres by using MRI visual and volumetric scoring systems. It also aims to assess the role of the score systems in predicting motor outcome. We developed qualitative and quantitative MRI scoring systems to grade the overall brain damage severity in 16 infants with total absence or near-total absence of cerebellar hemispheres. The qualitative scoring system assessed the severity of macrostructural abnormalities of cerebellum, brainstem, supratentorial gray and white matters, ventricles while the quantitative scoring system weighted the loss of brain tissue volumes, and gross motor function classification system (GMFCS) was used to assess motor function at 1- and 5-year follow-ups.Positive correlations between both MRI scores and GMFCS scales were detected at follow-ups (p > 0.05), but only the volumetric score could identify those infants developing higher levels of motor impairment.Brain volumetric MRI offers an unbiassed assessment of prenatal brain damage. The quantitative scoring system, performed at term equivalent age, can be a helpful tool for predicting the long-term motor outcome in extremely preterm infants with a near-total absence of cerebellum.

A Call for Early Detection of Cerebral Palsy

Cerebral palsy (CP) is the most common physical disability across the lifespan, but historically, CP has not been diagnosed before the age of 2 years. Barriers to early diagnosis ranged from lack of available biomarkers, absence of curative treatments, perceived stigma associated with a lifelong diagnosis, and a desire to rule out other diagnoses first. Most importantly, the fundamental question that remained was whether children would benefit from earlier detection and intervention given the paucity of research. However, evidence-based guidelines published in 2017 demonstrated that the General Movements Assessment, the Hammersmith Infant Neurological Examination, and neuroimaging can be combined with other elements such as a clinical history and standardized motor assessments to provide the highest predictive value for diagnosing CP as early as age 3 months in high-risk newborns. Implementation of these guidelines has been successful in decreasing the age at CP diagnosis, particularly in high-risk infant follow-up clinics with expertise in performing these assessments. Early detection of CP allows for clinical and research opportunities investigating earlier interventions during a critical period of neuroplasticity, with the goal of improving developmental trajectories for children and their families. New guidelines and research are now being developed with a focus on early, targeted interventions that continue to be studied, along with global detection initiatives.

Neuroimaging of Germinal Matrix and Intraventricular Hemorrhage in Premature Infants

Germinal matrix and intraventricular hemorrhage (GM-IVH) are the major causes of intracranial hemorrhage in premature infants. Cranial ultrasound (cUS) is the imaging modality of choice for diagnosing and classifying GM-IVH. Magnetic resonance imaging (MRI), usually performed at term-equivalent age, is more sensitive than cUS in identifying hemorrhage in the brain. Post-hemorrhagic ventricular dilatation is a significant complication of GM-IVH and correlates with adverse neurodevelopmental outcomes. In this review, we discuss the various imaging findings of GM-IVH in premature infants, focusing on the role of cUS and MRI.

andomised to early neuroprotection and neurorehabilitation: protocol for a follow-up study of participants from four randomised clinical trials

INTRODUCTION

School readiness includes cognitive, socio-emotional, language and physical growth and development domains which share strong associations with life-course opportunities. Children with cerebral palsy (CP) are at increased risk of poor school readiness compared with their typically developing peers. Recently, earlier diagnosis of CP has allowed interventions to commence sooner, harnessing neuroplasticity. First, we hypothesise that early referral to intervention for children at-risk of CP will lead to improved school readiness at 4-6 years relative to placebo or care as usual. Second, we hypothesise that receipt of early diagnosis and early intervention will lead to cost-savings in the form of reduced healthcare utilisation.

METHODS AND ANALYSIS

Infants identified as at-risk of CP ≤6 months corrected age (n=425) recruited to four randomised trials of neuroprotectants (n=1), early neurorehabilitation (n=2) or early parenting support (n=1) will be re-recruited to one overarching follow-up study at age 4-6 years 3 months. A comprehensive battery of standardised assessments and questionnaires will be administered to assess all domains of school readiness and associated risk factors. Participants will be compared with a historical control group of children (n=245) who were diagnosed with CP in their second year of life. Mixed-effects regression models will be used to compare school readiness outcomes between those referred for early intervention versus placebo/care-as-usual. We will also compare health-resource use associated with early diagnosis and intervention versus later diagnosis and intervention.

ETHICS AND DISSEMINATION

The Children's Health Queensland Hospital and Health Service, The University of Queensland, University of Sydney, Monash University and Curtin University Human Research Ethics Committees have approved this study. Informed consent will be sought from the parent or legal guardian of every child invited to participate. Results will be disseminated in peer-reviewed journals, scientific conferences and professional organisations, and to people with lived experience of CP and their families.

TRIAL REGISTRATION NUMBER

ACTRN12621001253897.

Early brain morphometrics from neonatal MRI predict motor and cognitive outcomes at 2-years corrected age in very preterm infants

Infants born very preterm face a range of neurodevelopmental challenges in cognitive, language, behavioural and/or motor domains. Early accurate identification of those at risk of adverse neurodevelopmental outcomes, through clinical assessment and Magnetic Resonance Imaging (MRI), enables prognostication of outcomes and the initiation of targeted early interventions. This study utilises a prospective cohort of 181 infants born <31 weeks gestation, who had 3T MRIs acquired at 29-35 weeks postmenstrual age and a comprehensive neurodevelopmental evaluation at 2 years corrected age (CA). Cognitive, language and motor outcomes were assessed using the Bayley Scales of Infant and Toddler Development - Third Edition and functional motor outcomes using the Neuro-sensory Motor Developmental Assessment. By leveraging advanced structural MRI pre-processing steps to standardise the data, and the state-of-the-art developing Human Connectome Pipeline, early MRI biomarkers of neurodevelopmental outcomes were identified. Using Least Absolute Shrinkage and Selection Operator (LASSO) regression, significant associations between brain structure on early MRIs with 2-year outcomes were obtained (r = 0.51 and 0.48 for motor and cognitive outcomes respectively) on an independent 25% of the data. Additionally, important brain biomarkers from early MRIs were identified, including cortical grey matter volumes, as well as cortical thickness and sulcal depth across the entire cortex. Adverse outcome on the Bayley-III motor and cognitive composite scores were accurately predicted, with an Area Under the Curve of 0.86 for both scores. These associations between 2-year outcomes and patient prognosis and early neonatal MRI measures demonstrate the utility of imaging prior to term equivalent age for providing earlier commencement of targeted interventions for infants born preterm.

Detection of Global Brain Injury Using Point-of-Care Neonatal MRI Scanner

BACKGROUND

 Conventional magnetic resonance imaging (MRI) neuroimaging of infants is complicated by the need to transport infants outside the neonatal intensive care unit (NICU), often to distant areas of the hospital.

PRIMARY OBJECTIVE

 The main aim of this study was to evaluate and compare scoring of images from a novel 1T MRI, which enables neuroimaging within the NICU, with those from a conventional MRI.

SECONDARY OBJECTIVE

 The second aim of this study was to document improved expediency, and thereby greater patient safety, as reflected by decreased transport time.

MATERIALS AND METHODS

 Thirty premature infants (mean gestational age: 28.8 ± 2.1 weeks) were scanned consecutively on the novel 1T and 1.5T conventional scanners at term-equivalent age. Orthogonal T1- and T2-weighted images were acquired and reviewed. A global brain abnormality score (Kidokoro) was assigned independently to all images by two radiologists. Interrater agreement was evaluated using the kappa statistic and interscanner agreement was evaluated by Bland-Altman analysis. Transport time to and from both scanners was monitored and compared.

RESULTS

 Weighted kappas were 0.77 (standard error of measurement [SEM] 0.08; confidence interval [CI]: 0.62-0.92) and 0.86 (SEM: 0.07; CI: 0.73-1), for the 1T and 1.5T scanners, respectively, reflecting substantial interrater agreement. Bland-Altman analysis showed excellent agreement between the two scanners.Transport time was 8 ± 6 minutes for the 1T MRI versus 46 ± 21 minutes for the conventional MRI (p < 0.00001). No adverse events were recorded during transport. Standard transport times will vary from institution to institution.

CONCLUSIONS

 Kidokoro scores are similar when comparing images obtained from a 1T MRI with those of a conventional 1.5T MRI, reflecting comparable image quality. Transport time was significantly decreased using the 1T neonatal MRI.

Biomedical and Psychosocial Determinants of Early Neurodevelopment After Preterm Birth

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

Effect of a NICU to Home Physical Therapy Intervention on White Matter Trajectories, Motor Skills, and Problem-Solving Skills of Infants Born Very Preterm: A Case Series

Infants born very preterm (VPT; ≤29 weeks of gestation) are at high risk of developmental disabilities and abnormalities in neural white matter characteristics. Early physical therapy interventions such as Supporting Play Exploration and Early Development Intervention (SPEEDI2) are associated with improvements in developmental outcomes. Six VPT infants were enrolled in a randomised clinical trial of SPEEDI2 during the transition from the neonatal intensive care unit to home over four time points. Magnetic resonance imaging scans and fixel-based analysis were performed, and fibre density (FD), fibre cross-section (FC), and fibre density and cross-section values (FDC) were computed. Changes in white matter microstructure and macrostructure were positively correlated with cognitive, motor, and motor-based problem solving over time on developmental assessments. In all infants, the greatest increase in FD, FC, and FDC occurred between Visit 1 and 2 (mean chronological age: 2.68-6.22 months), suggesting that this is a potential window of time to optimally support adaptive development. Results warrant further studies with larger groups to formally compare the impact of intervention and disparity on neurodevelopmental outcomes in infants born VPT.

'Low-normal' motor skills in infants at high risk for poor developmental outcomes: A prevalence and prognostic study

AIM

To investigate the prevalence and prognostic value of 'low-normal' motor skills in infants at high-risk for poor developmental outcomes.

METHOD

Infants born extremely low-birthweight and extremely preterm discharged from neonatal intensive care between 2015 and 2018 completed the Alberta Infant Motor Scale (AIMS), Neuro-Sensory Motor Developmental Assessment (NSMDA) at corrected age 4, 8, and 12 months, and Griffiths Mental Development Scale at corrected age 12 months.

RESULTS

Participating infants (n = 191) with a mean gestational age (95% confidence interval [CI]) of 26.80 weeks (26.60, 27.1) and mean birthweight (95% CI) of 869 grams (843, 895) included 45 (23.80%) infants small for gestational age. AIMS rated 50.32%, 35.37%, and 14.86% of infants within the 'low-normal' motor skills range (1-2 SD below the mean for age) at 4, 8, and 12 months respectively. Of the infants within the AIMS 'low-normal' skills range, 55.70%, 88.46%, and 59.10% were classified as having impairment by NSMDA at 4, 8, and 12 months respectively. Griffiths assessment at 12 months identified only 7.33% of infants with 'low-normal' skills and 3.33% with motor disability. Minimal motor impairment rating on the NSMDA at 4 or 8 months significantly predicted general development at 12 months.

INTERPRETATION

High-risk infants with 'low-normal' motor skills may warrant referral to early intervention as associated impairment represents increased risk for poorer general development outcomes.

WHAT THIS PAPER ADDS

High prevalence of 'low-normal' motor skill exists in high-risk infants. Clinical motor assessment validly identifies infants with motor impairment. Minimal motor impairment in high-risk infants is prognostic of general development. High-risk infants with 'low-normal' motor skills may warrant early intervention. Griffiths Scales of Child Development, Third Edition assessment at 12-months age may under-identify motor difficulties.

Neurological examination at 32-weeks postmenstrual age predicts 12-month cognitive outcomes in very preterm-born infants

BACKGROUND

To determine the diagnostic accuracy of Hammersmith Neonatal Neurological Examination (HNNE) at 30-32 weeks postmenstrual age (PMA, 'Early') and term equivalent age (TEA) in infants born <31 weeks PMA to predict cognitive outcomes at 12 months corrected age (CA).

METHODS

Prospective cohort study of 119 infants (73 males; median 28.4 weeks gestational age at birth) who underwent Early and TEA HNNE. At 12 months CA, 104 participants completed Bayley Scales of Infant and Toddler Development, 3rd Edition, (Bayley-III). Optimum cut-off points for each HNNE subscale were determined to establish diagnostic accuracy for predicting adverse cognitive outcomes on the Bayley-III Cognitive Composite Scale (≤85).

RESULTS

The best diagnostic accuracy for HNNE total score at 30-32 weeks PMA predicting cognitive impairment occurred at cut-off ≤16.7 (sensitivity (Se) = 71%, specificity (Sp) = 51%). The Abnormal Signs subscale demonstrated the best balance of sensitivity/specificity combination (Se = 71%, Sp = 71%; cut-off ≤1.5). For HNNE at TEA, the total score at cut-off ≤24.5 had Se = 71% and Sp = 47% for predicting cognitive impairment. The Tone Patterns subscale demonstrated the strongest diagnostic accuracy at TEA (Se = 71%, Sp = 63%; cut-off ≤3).

CONCLUSIONS

Early and TEA HNNE demonstrated moderate diagnostic accuracy for cognitive outcomes at 12-months CA in infants born <31 weeks gestational age.

CLINICAL TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry; Trial Registration Number: ACTRN12613000280707; web address of trial: http://www.ANZCTR.org.au/ACTRN12613000280707.aspx .

IMPACT

Early Hammersmith Neonatal Neurological Examination (HNNE) assessment at 30-32 weeks postmenstrual age has moderate diagnostic accuracy for cognitive outcomes at 12 months corrected age in infants born <31 weeks gestation. Early HNNE at 30-32 weeks has stronger predictive validity than HNNE at term equivalent age. Early HNNE may provide an early marker for risk-stratification to optimise the planning of post-discharge support and follow-up services for infants born preterm.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A novel magnetic resonance imaging-based scoring system to predict outcome in neonates born preterm with intraventricular haemorrhage

AIM

To create a magnetic resonance imaging (MRI)-based scoring system specific to neonates born preterm with intraventricular haemorrhage (IVH), which could serve as a reliable prognostic indicator for later development and might allow for improved outcome prediction, individually-tailored parental counselling, and clinical decision-making.

METHOD

This retrospective, two-center observational cohort study included 103 infants born preterm with IVH (61 males, 42 females; median gestational age 26wks 6d), born between 2000 and 2016. Term-equivalent MRI was evaluated using a novel scoring system consisting of 11 items. A total MRI score was calculated and correlated with neurodevelopment between 2 years and 3 years of age. Prediction models for outcome were defined.

RESULTS

The proposed MRI scoring system showed high correlation and strong predictive ability with regard to later cognitive and motor outcome. The prediction models were translated into easy-to-use tables, allowing developmental risk assessment.

INTERPRETATION

The proposed MRI-based scoring system was created especially for infants born preterm with IVH and enables a comprehensive assessment of important brain areas as well as potential additional abnormalities commonly associated with IVH. Thus, it better represents the severity of brain damage when compared with the conventional IVH classification. Our scoring system should provide clinicians with valuable information, to optimize parental counselling and clinical decision-making.

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

CONTEXT

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

METHODS

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

RESULTS

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

CONCLUSION AND PERSPECTIVE

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

Early detection relationship of cerebral palsy markers using brain structure and general movements in infants born <32 weeks gestational age

AIM

To detect early brain structural and clinical functional markers of brain injury and development based on a magnetic resonance imaging (MRI) scoring system and a general movement assessment (GMA) for preterm infants later diagnosed with cerebral palsy (CP).

STUDY DESIGN

Retrospective cohort study. General movements (GMs) were scored according to a semiquantitative scoring system: the GMs optimality score (GMOS) at preterm and term ages and the Motor Optimality Score (MOS) at the corrected age of 3 months after birth. Brain magnetic resonance imaging (MRI) at term-equivalent age was scored using an MRI scoring system. We analyzed the relationship between the early degree of cerebral white matter (WM) abnormality and the GMOS and the MOS for infants born <32 weeks gestational age later diagnosed with CP in a comparison group of neurotypical controls.

SUBJECTS

Sixteen preterm infants were included in this study who underwent MRI and GMs assessment. 8 out of the 16 preterm infants were later diagnosed with CP, while the other 8 infants with normal motor development (N) were placed into the control group. Their median gestational age was 30w6d and 27w6d for each group respectively.

RESULTS

The cerebral WM MRI scores were significantly higher in the CP group than in the control group (p < 0.01). The GMOS and MOS were significantly higher in the control group than in the CP group (p < 0.05). The MOS showed a strong correlation to the cerebral WM MRI score (r = -0.88) and the subscale of cerebral WM items (the cystic degeneration and the focal signal abnormalities) of the MRI score (r = -0.94) in the CP group. The MOS also showed a correlation with corrected biparietal diameter (cBPD) in the preterm infant group with CP (r = 0.75). Results of linear regression analyses between term MRI and GMs measures in preterm infants with CP are presented. Cerebral WM scores were associated with the MOS (β = -0.63; 95%CI = -0.97, -0.29; p < 0.01). Cerebral WM injury, including the subscale of cystic degeneration and focal signal abnormalities was closely associated with the MOS (β = -0.83; 95%CI = -1.13, -0.54; p < 0.001).

CONCLUSION

Cerebral WM scores show a strong association with a decreased motor performance on the MOS in preterm infants later diagnosed with CP. Severe white matter injury and significantly decreased MOS scores may provide useful early markers and strong evidence to early predict the risk of later development of cerebral palsy in preterm infants.

Early clinical and MRI biomarkers of cognitive and motor outcomes in very preterm born infants

BACKGROUND

This study aimed to identify which MRI and clinical assessments, alone or in combination, from (i) early (32 weeks postmenstrual age, PMA), (ii) term equivalent age (TEA) and (iii) 3 months corrected age (CA) are associated with motor or cognitive outcomes at 2 years CA in infants born <31 weeks gestation.

METHODS

Prospective cohort study of 98 infants who underwent early and TEA MRI (n = 59 males; median birth gestational age 28 + 5 weeks). Hammersmith Neonatal Neurological Examination (HNNE), NICU Neonatal Neurobehavioural Scale and General Movements Assessment (GMs) were performed early and at TEA. Premie-Neuro was performed early and GMs, Test of Infant Motor Performance and visual assessment were performed at TEA and 3 months CA. Neurodevelopmental outcomes were determined using Bayley Scales of Infant and Toddler Development 3rd edition.

RESULTS

The best combined motor outcome model included 3-month GMs (β = -11.41; 95% CI = -17.34, -5.49), TEA MRI deep grey matter score (β = -6.23; 95% CI = -9.47, -2.99) and early HNNE reflexes (β = 3.51; 95% CI = 0.86, 6.16). Combined cognitive model included 3-month GMs (β = -10.01; 95% CI = -15.90, -4.12) and TEA HNNE score (β = 1.33; 95% CI = 0.57, 2.08).

CONCLUSION

Early neonatal neurological assessment improves associations with motor outcomes when combined with term MRI and 3-month GMs. Term neurological assessment combined with 3-month GMs improves associations with cognitive outcomes.

IMPACT

We present associations between 32- and 40-week MRI, comprehensive clinical assessments and later 2-year motor and cognitive outcomes for children born <31 weeks gestation. MRI and clinical assessment of motor, neurological and neurobehavioural function earlier than term equivalent age in very preterm infants is safe and becoming more available in clinical settings. Most of these children are discharged from hospital before term age and so completing assessments prior to discharge can assist with follow up. MRI and neurological assessment prior to term equivalent age while the child is still in hospital can provide earlier identification of children at highest risk of adverse outcomes and guide follow-up screening and intervention services.

Relationship between the Quantitative Indicators of Cranial MRI and the Early Neurodevelopment of Preterm Infants

Aim

To explore the relationship between the quantitative indicators (biparietal width, interhemispheric distance) of the cranial MRI for preterm infants at 37 weeks of postmenstrual age (PMA) and neurodevelopment at 6 months of corrected age.

Methods

A total of 113 preterm infants (gestational age < 37 weeks) delivered in the Obstetrics Department of the First People's Hospital of Lianyungang from September 2018 to February 2020 and directly transferred to the Neonatology Department for treatment were enrolled in this study. Based on their development quotient (DQ), the patients were divided into the normal (DQ ≥ 85, n = 76) group and the abnormal (DQ < 85, n = 37) group. Routine cranial MRI (cMRI) was performed at 37 weeks of PMA to measure the biparietal width (BPW) and interhemispheric distance (IHD). At the corrected age of 6 months, Development Screening Test (for children under six) was used to assess the participants' neurodevelopment.

Results

Univariate analysis showed statistically significant differences in BPW, IHD, and the incidence of bronchopulmonary dysplasia between the normal and the abnormal groups (P < 0.05), while no statistically significant differences were found in maternal complications and other clinical conditions between the two groups (P > 0.05). Binary logistic regression analysis demonstrated statistically significant differences in IHD and BPW between the normal and the abnormal groups (95% CI: 1.629-12.651 and 0.570-0.805, respectively; P = 0.004 and P < 0.001, respectively), while no significant differences were found in the incidence of bronchopulmonary dysplasia between the two groups (95% CI: 0.669-77.227, P = 0.104). Receiver operating characteristic curve revealed that the area under the curve of BPW, IHD, and the joint predictor (BPW + IHD) were 0.867, 0.805, and 0.881, respectively (95% CI: 0.800-0.933, 0.710-0.900, and 0.819-0.943, respectively; all P values < 0.001).

Conclusion

BPW and IHD, the two quantitative indicators acquired by cMRI, could predict the neurodevelopmental outcome of preterm infants at the corrected age of 6 months. The combination of the two indicators showed an even higher predictive value.

Early Screening of Visual Processing Dysfunctions in Children Born Very or Extremely Preterm

Introduction: Children with early brain damage or dysfunction are at risk of developing cerebral visual impairment (CVI), including visual processing dysfunctions (VPD), which currently remain largely undetected until school age. Our aim was to systematically screen for possible VPD in children born very or extremely preterm from 1 to 2 years corrected age (CA) and to evaluate the effectiveness of early referral. Method: We included N = 48 children born < 30 weeks from 1 year CA. They underwent a two-step VPD screening based on (1) neurological signs indicative of visual brain damage evaluated by neonatologists and/or pediatric neurologist and (2) a functional assessment of visual orienting functions (VOF) with an eye tracking-based test. If at least one of these assessments was abnormal for their age, the children were classified as a risk of VPD and referred to undergo conventional visual diagnostics: ophthalmic exam and visual function assessment (VFA). At 2 years CA, VOF screening was repeated and neurodevelopment was assessed. Results: 18 children (38%) were classified as at risk of VPD at 1 year CA. 7 children had abnormal neurological signs, 5 children had abnormal VOF, and 6 children had both. Subsequent ophthalmic exams (N = 14) showed severe hypermetropia in 21% and strabismus in 14%. VFA (N = 10) showed abnormal visual function and behavior in only 1 child. At 2 years CA, the total group showed an increase in abnormal VOF. Whereas the children at risk showed some normalization, the group without VPD risk at 1 year CA showed deterioration of VOF. Neurodevelopmental outcome did not clearly differ between risk groups. Conclusion: Our findings show a substantial risk of VPD during visual screening (in 38%) at 1 year CA, but relatively few deficits on subsequent conventional ophthalmic exams and VFA. The data suggest that most conventional visual diagnostic methods at this young age are not related to the established VPD risks. VOF assessment should be used complimentary to these methods. The fact that at 2 years CA the number of children with a VPD risk based on abnormal VOF increased argues for more extensive and continuous screening in risk groups, at least until school age.

Automating Quantitative Measures of an Established Conventional MRI Scoring System for Preterm-Born Infants Scanned between 29 and 47 Weeks' Postmenstrual Age

BACKGROUND AND PURPOSE

Conventional MR imaging scoring is a valuable tool for risk stratification and prognostication of outcomes, but manual scoring is time-consuming, operator-dependent, and requires high-level expertise. This study aimed to automate the regional measurements of an established brain MR imaging scoring system for preterm neonates scanned between 29 and 47 weeks' postmenstrual age.

MATERIALS AND METHODS

This study used T2WI from the longitudinal Prediction of PREterm Motor Outcomes cohort study and the developing Human Connectome Project. Measures of biparietal width, interhemispheric distance, callosal thickness, transcerebellar diameter, lateral ventricular diameter, and deep gray matter area were extracted manually (Prediction of PREterm Motor Outcomes study only) and automatically. Scans with poor quality, failure of automated analysis, or severe pathology were excluded. Agreement, reliability, and associations between manual and automated measures were assessed and compared against statistics for manual measures. Associations between measures with postmenstrual age, gestational age at birth, and birth weight were examined (Pearson correlation) in both cohorts.

RESULTS

A total of 652 MRIs (86%) were suitable for analysis. Automated measures showed good-to-excellent agreement and good reliability with manual measures, except for interhemispheric distance at early MR imaging (scanned between 29 and 35 weeks, postmenstrual age; in line with poor manual reliability) and callosal thickness measures. All measures were positively associated with postmenstrual age (r = 0.11-0.94; R² = 0.01-0.89). Negative and positive associations were found with gestational age at birth (r = -0.26-0.71; R² = 0.05-0.52) and birth weight (r = -0.25-0.75; R² = 0.06-0.56). Automated measures were successfully extracted for 80%-99% of suitable scans.

CONCLUSIONS

Measures of brain injury and impaired brain growth can be automatically extracted from neonatal MR imaging, which could assist with clinical reporting.

Adverse effects of perinatal illness severity on neurodevelopment are partially mediated by early brain abnormalities in infants born very preterm

BACKGROUND

We sought to determine the mediating effects of magnetic resonance imaging (MRI) biomarkers at term gestation on the relationship between perinatal illness severity and neurodevelopment.

METHODS

The Clinical Risk Index for Babies-second edition (CRIB-II) was correlated with indices of brain maturation or injury and neurodevelopment at 2-year follow-up in infants born less than 32 weeks gestation. Using a counterfactual mediation analysis, associations between CRIB-II, MRI biomarkers, and neurodevelopment were confirmed, followed by an assessment of the mediating effects of MRI biomarkers on the relationship between CRIB-II and neurodevelopment.

RESULTS

CRIB-II correlated significantly with neurodevelopment and MRI biomarkers of brain injury or cortical maturation. Two MRI biomarkers, cortical surface area and global injury score, were associated with neurodevelopmental scores at follow-up and included in mediation analyses.

CONCLUSION

Biomarkers of cortical maturation or brain injury at term-equivalent age mediated a substantial portion of the risks conveyed by perinatal illness severity on neurodevelopmental outcomes at 2 years corrected age.

Ultrasonographic Estimation of Total Brain Volume: 3D Reliability and 2D Estimation. Enabling Routine Estimation During NICU Admission in the Preterm Infant

Objectives: The aim of this study is to explore if manually segmented total brain volume (TBV) from 3D ultrasonography (US) is comparable to TBV estimated by magnetic resonance imaging (MRI). We then wanted to test 2D based TBV estimation obtained through three linear axes which would enable monitoring brain growth in the preterm infant during admission. Methods: We included very low birth weight preterm infants admitted to our neonatal intensive care unit (NICU) with normal neuroimaging findings. We measured biparietal diameter, anteroposterior axis, vertical axis from US and MRI and TBV from both MRI and 3D US. We calculated intra- and interobserver agreement within and between techniques using the intraclass correlation coefficient and Bland-Altman methodology. We then developed a multilevel prediction model of TBV based on linear measurements from both US and MRI, compared them and explored how they changed with increasing age. The multilevel prediction model for TBV from linear measures was tested for internal and external validity and we developed a reference table for ease of prediction of TBV. Results: We used measurements obtained from 426 US and 93 MRI scans from 118 patients. We found good intra- and interobserver agreement for all the measurements. US measurements were reliable when compared to MRI, including TBV which achieved excellent agreement with that of MRI [ICC of 0.98 (95% CI 0.96-0.99)]. TBV estimated through 2D measurements of biparietal diameter, anteroposterior axis, and vertical axis was comparable among both techniques. We estimated the population 95% confidence interval for the mean values of biparietal diameter, anteroposterior axis, vertical axis, and total brain volume by post-menstrual age. A TBV prediction table based on the three axes is proposed to enable easy implementation of TBV estimation in routine 2D US during admission in the NICU. Conclusions: US measurements of biparietal diameter, vertical axis, and anteroposterior axis are reliable. TBV segmented through 3D US is comparable to MRI estimated TBV. 2D US accurate estimation of TBV is possible through biparietal diameter, vertical, and anteroposterior axes.

Brain Damage and Visuospatial Impairments: Exploring Early Structure-Function Associations in Children Born Very Preterm

BACKGROUND

To provide insight into early neurosensory development in children born very preterm, we assessed the association between early structural brain damage and functional visuospatial attention and motion processing from one to two years corrected age.

METHODS

In 112 children born at less than 32 weeks gestational age, we assessed brain damage and growth with a standardized scoring system on magnetic resonance imaging (MRI; 1.5 Tesla) scans performed at 29 to 35 weeks gestational age. Of the children with an MRI scan, 82 participated in an eye tracking-based assessment of visuospatial attention and motion processing (Tobii T60XL) at one year corrected age and 59 at two years corrected age.

RESULTS

MRI scoring showed good intra- and inter-rater reproducibility. At one year, 10% children had delayed attentional reaction times and 23% had delayed motion reaction times. Moderate to severe brain damage significantly correlated with slower visuospatial reaction times. At two years, despite attention and motion reaction times becoming significantly faster, 20% had delayed attentional reaction times and 35% had delayed motion reaction times, but no correlations with MRI scores were found. The presence of structural brain damage was associated with abnormal functional performance over age.

CONCLUSIONS

The present study indicates an association between moderate to severe brain damage and visuospatial attention and motion processing dysfunction at one year corrected age. This provides a new perspective on comprehensive MRI scoring and quantitative functional visuospatial assessments and their applicability in children born very preterm in their first years of life.

Prediction of childhood brain outcomes in infants born preterm using neonatal MRI and concurrent clinical biomarkers (PREBO-6): study protocol for a prospective cohort study

INTRODUCTION

Infants born very preterm are at risk of adverse neurodevelopmental outcomes, including cognitive deficits, motor impairments and cerebral palsy. Earlier identification enables targeted early interventions to be implemented with the aim of improving outcomes.

METHODS AND ANALYSIS

Protocol for 6-year follow-up of two cohorts of infants born <31 weeks gestational age (PPREMO: Prediction of Preterm Motor Outcomes; PREBO: Prediction of Preterm Brain Outcomes) and a small term-born reference sample in Brisbane, Australia. Both preterm cohorts underwent very early MRI and concurrent clinical assessment at 32 and 40 weeks postmenstrual age (PMA) and were followed up at 3, 12 and 24 months corrected age (CA). This study will perform MRI and electroencephalography (EEG). Primary outcomes include the Movement Assessment Battery for Children second edition and Full-Scale IQ score from the Wechsler Intelligence Scale for Children fifth edition (WISC-V). Secondary outcomes include the Gross Motor Function Classification System for children with cerebral palsy; executive function (Behavior Rating Inventory of Executive Function second edition, WISC-V Digit Span and Picture Span, Wisconsin Card Sorting Test 64 Card Version); attention (Test of Everyday Attention for Children second edition); language (Clinical Evaluation of Language Fundamentals fifth edition), academic achievement (Woodcock Johnson IV Tests of Achievement); mental health and quality of life (Development and Well-Being Assessment, Autism Spectrum Quotient-10 Items Child version and Child Health Utility-9D).

AIMS

Examine the ability of early neonatal MRI, EEG and concurrent clinical measures at 32 weeks PMA to predict motor, cognitive, language, academic achievement and mental health outcomes at 6 years CA.Determine if early brain abnormalities persist and are evident on brain MRI at 6 years CA and the relationship to EEG and concurrent motor, cognitive, language, academic achievement and mental health outcomes.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from Human Research Ethics Committees at Children's Health Queensland (HREC/19/QCHQ/49800) and The University of Queensland (2019000426). Study findings will be presented at national and international conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ACTRN12619000155190p. WEB ADDRESS OF TRIAL: http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12619000155190p.

Predicting motor outcome in preterm infants from very early brain diffusion MRI using a deep learning convolutional neural network (CNN) model

BACKGROUND AND AIMS

Preterm birth imposes a high risk for developing neuromotor delay. Earlier prediction of adverse outcome in preterm infants is crucial for referral to earlier intervention. This study aimed to predict abnormal motor outcome at 2 years from early brain diffusion magnetic resonance imaging (MRI) acquired between 29 and 35 weeks postmenstrual age (PMA) using a deep learning convolutional neural network (CNN) model.

METHODS

Seventy-seven very preterm infants (born <31 weeks gestational age (GA)) in a prospective longitudinal cohort underwent diffusion MR imaging (3T Siemens Trio; 64 directions, b ​= ​2000 ​s/mm²). Motor outcome at 2 years corrected age (CA) was measured by Neuro-Sensory Motor Developmental Assessment (NSMDA). Scores were dichotomised into normal (functional score: 0, normal; n ​= ​48) and abnormal scores (functional score: 1-5, mild-profound; n ​= ​29). MRIs were pre-processed to reduce artefacts, upsampled to 1.25 ​mm isotropic resolution and maps of fractional anisotropy (FA) were estimated. Patches extracted from each image were used as inputs to train a CNN, wherein each image patch predicted either normal or abnormal outcome. In a postprocessing step, an image was classified as predicting abnormal outcome if at least 27% (determined by a grid search to maximise the model performance) of its patches predicted abnormal outcome. Otherwise, it was considered as normal. Ten-fold cross-validation was used to estimate performance. Finally, heatmaps of model predictions for patches in abnormal scans were generated to explore the locations associated with abnormal outcome.

RESULTS

For the identification of infants with abnormal motor outcome based on the FA data from early MRI, we achieved mean sensitivity 70% (standard deviation SD 19%), mean specificity 74% (SD 39%), mean AUC (area under the receiver operating characteristic curve) 72% (SD 14%), mean F1 score of 68% (SD 13%) and mean accuracy 73% (SD 19%) on an unseen test data set. Patch-based prediction heatmaps showed that the patches around the motor cortex and somatosensory regions were most frequently identified by the model with high precision (74%) as a location associated with abnormal outcome. Part of the cerebellum, and occipital and frontal lobes were also highly associated with abnormal NSMDA/motor outcome.

DISCUSSION/CONCLUSION

This study established the potential of an early brain MRI-based deep learning CNN model to identify preterm infants at risk of a later motor impairment and to identify brain regions predictive of adverse outcome. Results suggest that predictions can be made from FA maps of diffusion MRIs well before term equivalent age (TEA) without any prior knowledge of which MRI features to extract and associated feature extraction steps. This method, therefore, is suitable for any case of brain condition/abnormality. Future studies should be conducted on a larger cohort to re-validate the robustness and effectiveness of these models.

Predicting developmental outcomes in preterm infants: A simple white matter injury imaging rule

OBJECTIVE

To develop a simple imaging rule to predict neurodevelopmental outcomes at 4.5 years in a cohort of preterm neonates with white matter injury (WMI) based on lesion location and examine whether clinical variables enhance prediction.

METHODS

Sixty-eight preterm neonates born 24-32 weeks' gestation (median 27.7 weeks) were diagnosed with WMI on early brain MRI scans (median 32.3 weeks). 3D T1-weighted images of 60 neonates with 4.5-year outcomes were reformatted and aligned to the posterior commissure-eye plane and WMI was classified by location: anterior or posterior-only to the midventricle line on the reformatted axial plane. Adverse outcomes at 4.5 years were defined as Wechsler Preschool and Primary Scale of Intelligence full-scale IQ <85, cerebral palsy, or Movement Assessment Battery for Children, second edition percentile <5. The prediction of adverse outcome by WMI location, intraventricular hemorrhage (IVH), bronchopulmonary dysplasia (BPD), and retinopathy of prematurity (ROP) was assessed using multivariable logistic regression.

RESULTS

Six children had adverse cognitive outcomes and 17 had adverse motor outcomes. WMI location predicted cognitive outcomes in 90% (area under receiver operating characteristic curve [AUC] 0.80) and motor outcomes in 85% (AUC 0.75). Adding IVH, BPD, and ROP to the model enhances the predictive strength for cognitive and motor outcomes (AUC 0.83 and 0.88, respectively). Rule performance was confirmed in an independent cohort of children with WMI.

CONCLUSIONS

WMI on early MRI can be classified by location to predict preschool age outcomes in children born preterm. The predictive value of this WMI classification is enhanced by considering clinical factors apparent by term-equivalent age.

Fetal and neonatal neuroimaging

Magnetic resonance imaging (MRI) can provide detail of the soft tissues of the fetal and neonatal brain that cannot be obtained by any other imaging modality. Conventional T1 and T2 weighted sequences provide anatomic detail of the normally developing brain and can demonstrate lesions, including those associated with preterm birth, hypoxic ischemic encephalopathy, perinatal arterial stroke, infections, and congenital malformations. Specialized imaging techniques can be used to assess cerebral vasculature (magnetic resonance angiography and venography), cerebral metabolism (magnetic resonance spectroscopy), cerebral perfusion (arterial spin labeling), and function (functional MRI). A wealth of quantitative tools, most of which were originally developed for the adult brain, can be applied to study the developing brain in utero and postnatally including measures of tissue microstructure obtained from diffusion MRI, morphometric studies to measure whole brain and regional tissue volumes, and automated approaches to study cortical folding. In this chapter, we aim to describe different imaging approaches for the fetal and neonatal brain, and to discuss their use in a range of clinical applications.

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

AIM

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

METHOD

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

RESULTS

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

INTERPRETATION

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

WHAT THIS PAPER ADDS

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

Relationship between very early brain structure and neuromotor, neurological and neurobehavioral function in infants born <31 weeks gestational age

AIM

This study aimed to examine associations between structural MRI and concurrent motor, neurological and neurobehavioral measures at 30-32 weeks postmenstrual age (PMA; 'Early'), and at term equivalent age ('Term').

METHOD

In this prospective cohort study, infants underwent Early MRI (n = 119; 73 male; median 32 weeks 1 day PMA) and Term MRI (n = 102; 61 male; median 40 weeks 4 days PMA) at 3 T. Structural images were scored generating white matter (WM), cortical gray matter, deep gray matter, cerebellar and global brain abnormality scores. Clinical measures were General Movements Assessment (GMs), Hammersmith Neonatal Neurological Examination (HNNE) and NICU Neonatal Neurobehavioral Scale (NNNS). The Premie-Neuro was administered Early and the Test of Infant Motor Performance (TIMP) and a visual assessment at Term.

RESULTS

Early MRI cerebellar scores were strongly associated with neurological components of HNNE (reflexes), NNNS (Hypertonicity), the Premie-Neuro neurological subscale (regression coefficient β = -0.06; 95% confidence interval CI = -0.09, -0.04; p < .001) and cramped-synchronized GMs (β = 1.10; 95%CI = 0.57, 1.63; p < .001). Term MRI WM and global scores were strongly associated with the TIMP (WM β = -1.02; 95%CI = -1.67, -0.36; p = .002; global β = -1.59; 95%CI = -2.62, -0.56; p = .001).

INTERPRETATION

Brain structure on Early and Term MRI was associated with concurrent motor, neurological and neurobehavioral function in very preterm infants.

Fixel-based analysis reveals alterations is brain microstructure and macrostructure of preterm-born infants at term equivalent age

Preterm birth causes significant disruption in ongoing brain development, frequently resulting in adverse neurodevelopmental outcomes. Brain imaging using diffusion MRI may provide valuable insight into microstructural properties of the developing brain. The aim of this study was to establish whether the recently introduced fixel-based analysis method, with its associated measures of fibre density (FD), fibre bundle cross-section (FC), and fibre density and bundle cross-section (FDC), is suitable for the investigation of the preterm infant brain at term equivalent age. High-angular resolution diffusion weighted images (HARDI) of 55 preterm-born infants and 20 term-born infants, scanned around term-equivalent age, were included in this study (3 T, 64 directions, b = 2000 s/mm²). Postmenstrual age at the time of MRI, and intracranial volume (FC and FDC only), were identified as confounding variables. Gestational age at birth was correlated with all fixel measures in the splenium of the corpus callosum. Compared to term-born infants, preterm infants showed reduced FD, FC, and FDC in a number of regions, including the corpus callosum, anterior commissure, cortico-spinal tract, optic radiations, and cingulum. Preterm infants with minimal macroscopic brain abnormality showed more extensive reductions than preterm infants without any macroscopic brain abnormality; however, little differences were observed between preterm infants with no and with minimal brain abnormality. FC showed significant reductions in preterm versus term infants outside regions identified with FD and FDC, highlighting the complementary role of these measures. Fixel-based analysis identified both microstructural and macrostructural abnormalities in preterm born infants, providing a more complete picture of early brain development than previous diffusion tensor imaging (DTI) based approaches.

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Gestational age at birth associated with measurements in corpus callosum splenium.

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Preterms without macroscopic brain abnormality show differences to term infants.

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No differences between preterms with minimal versus without abnormality detected.