MRI Changes in the Thalamus and Basal Ganglia of Full-Term Neonates with Perinatal Asphyxia

Developmental anatomy of the thalamus, perinatal lesions, and neurological development

The thalamic nuclei develop before a viable preterm age. GABAergic neuronal migration is especially active in the third trimester. Thalamic axons meet cortical axons during subplate activation and create the definitive cortical plate in the second and third trimesters. Default higher-order cortical driver connections to the thalamus are then replaced by the maturing sensory networks, in a process that is driven by first-order thalamic neurons. Surface electroencephalographic activity, generated first in the subplate and later in the cortical plate, gradually show oscillations based on the interaction of the cortex with thalamus, which is controlled by the thalamic reticular nucleus. In viable newborn infants, in addition to sensorimotor networks, the thalamus already contributes to visual, auditory, and pain processing, and to arousal and sleep. Isolated thalamic lesions may present as clinical seizures. In addition to asphyxia and stroke, infection and network injury are also common. Cranial ultrasound can be used to classify neonatal thalamic injuries based on functional parcelling of the mature thalamus. We provide ample illustration and a detailed description of the impact of neonatal focal thalamic injury on neurological development, and discuss the potential for neuroprotection based on thalamocortical plasticity.

"Feed-and-wrap" technique versus deep sedation for neonatal magnetic resonance imaging: a retrospective comparative study

OBJECTIVES

Neonatal MRI is usually performed under deep sedation, which is challenging-especially in low-weight premature patients. In addition, long-term side effects, such as neurotoxicity, are of concern. An alternative to sedation is to induce natural sleep by feeding and immobilising the child, the "feed-and-wrap" technique (FWT). The objective of this study was to evaluate differences in image quality between neonates examined under sedation and by using the FWT during the first four months of life.

MATERIALS AND METHODS

We retrospectively assessed image quality (based on a 4-point semiquantitative scale) of all MRI examinations in neonates performed at our institution between July 2009 and August 2022. Differences in image quality between examinations under sedation versus FWT were evaluated.

RESULTS

We included 432 consecutive patients, 243 (56%) using sedation and 189 (44%) using the FWT. Corrected age and body weight (mean ± SD: 3.7 ± 1.1 versus 4.5 ± 1.3 kg, p < 0.001) were significantly lower in the FWT group. The overall success rate in the FWT group was 95%. Image quality was slightly lower when using the FWT (mean ± SD: 3.7 ± 0.43 versus 3.96 ± 0.11, p < 0.001). Multivariate analysis showed a higher risk of acquiring sequences with diagnostic limitations in the FWT group (p < 0.001), increasing with corrected age (p = 0.048).

CONCLUSION

The FWT is a highly successful method to perform MRI scans in term and preterm neonates. Overall image quality is only slightly lower than under sedation. Especially in immature low-weight preterm patients, the FWT is a reliable option to perform MRI studies without exposing the child to risks associated with sedation.

CLINICAL RELEVANCE STATEMENT

The "feed-and-wrap" technique enables high-quality MRI examinations in neonates, including low-weight premature patients. Deep sedation for diagnostic MRI procedures in this age group, which has the risk of short- and long-term complications, can often be avoided.

KEY POINTS

Deeply sedating neonates for MR examinations comes with risks. Image quality is only slightly lower when using the "feed-and-wrap" technique. The "feed-and-wrap" technique is feasible even in low-weight premature infants.

Apparent diffusion coefficient values can predict neuromotor outcome in term neonates with hypoxic-ischaemic encephalopathy

AIM

To determine the apparent diffusion coefficient (ADC) in brain structures during the first 2 weeks of life and its relation with neurological outcome for hypoxic-ischaemic encephalopathy (HIE) in term neonates.

METHODS

We retrospectively evaluated 56 term-born neonates. The ADC values were measured for 11 brain regions. The clinical outcomes at least 2 years of age were defined as normal outcome, mild disability and severe disability. The area under curves (AUCs) by ROC analysis were performed to predict the neurodevelopmental outcomes. The clinical outcomes were compared between favourable outcome and adverse outcome and also between normal outcome and unfavourable outcome.

RESULTS

Thirty-four patients were judged as normal outcome, 10 as mild disability and 12 as severe disability. When the clinical outcomes were compared between favourable outcome and adverse outcome, the AUC on the 1st week was highest value at the thalamus. When the clinical outcomes were compared between normal outcome and unfavourable outcome, the AUC on the 1st week was highest at the thalamus.

CONCLUSION

The ADC values in the thalamus in the 1st week can predict the neurological outcome. The ADC values in centrum semiovale on the 2nd week can be used to predict neurodevelopmental outcomes.

Additional Value of 3-Month Cranial Magnetic Resonance Imaging in Infants with Neonatal Encephalopathy following Perinatal Asphyxia

OBJECTIVE

To assess the evolution of neonatal brain injury noted on magnetic resonance imaging (MRI), develop a score to assess brain injury on 3-month MRI, and determine the association of 3-month MRI with neurodevelopmental outcome in neonatal encephalopathy (NE) following perinatal asphyxia.

METHODS

This was a retrospective, single-center study including 63 infants with perinatal asphyxia and NE (n = 28 cooled) with cranial MRI <2 weeks and 2-4 months after birth. Both scans were assessed using biometrics, a validated injury score for neonatal MRI, and a new score for 3-month MRI, with a white matter (WM), deep gray matter (DGM), and cerebellum subscore. The evolution of brain lesions was assessed, and both scans were related to 18- to 24-month composite outcome. Adverse outcome included cerebral palsy, neurodevelopmental delay, hearing/visual impairment, and epilepsy.

RESULTS

Neonatal DGM injury generally evolved into DGM atrophy and focal signal abnormalities, and WM/watershed injury evolved into WM and/or cortical atrophy. Although the neonatal total and DGM scores were associated with composite adverse outcomes, the 3-month DGM score (OR 1.5, 95% CI 1.2-2.0) and WM score (OR 1.1, 95% CI 1.0-1.3) also were associated with composite adverse outcomes (occurring in n = 23). The 3-month multivariable model (including the DGM and WM subscores) had higher positive (0.88 vs 0.83) but lower negative predictive value (0.83 vs 0.84) than neonatal MRI. Inter-rater agreement for the total, WM, and DGM 3-month score was 0.93, 0.86, and 0.59.

CONCLUSIONS

In particular, DGM abnormalities on 3-month MRI, preceded by DGM abnormalities on the neonatal MRI, were associated with 18- to 24-month outcome, indicating the utility of 3-month MRI for treatment evaluation in neuroprotective trials. However, the clinical usefulness of 3-month MRI seems limited compared with neonatal MRI.

Predictive Value of MRI in Hypoxic-Ischemic Encephalopathy Treated with Therapeutic Hypothermia

Background: Hypoxic-ischemic encephalopathy (HIE) is a severe pathology, and no unique predictive biomarker has been identified. Our aims are to identify associations of perinatal and outcome parameters with morphological anomalies and ADC values from MRI. The secondary aims are to define a predictive ADC threshold value and detect ADC value fluctuations between MRIs acquired within 7 days (MR0) and at 1 year (MR1) of birth in relation to perinatal and outcome parameters. Methods: Fifty-one term children affected by moderate HIE treated with hypothermia and undergoing MRI0 and MRI1 were recruited. Brain MRIs were evaluated through the van Rooij score, while ADC maps were co-registered on a standardized cerebral surface, on which 29 ROIs were drawn. Statistical analysis was performed in Matlab, with the statistical significance value at 0.05. Results: ADC0 < ADC1 in the left and right thalami, left and right frontal white matter, right visual cortex, and the left dentate nucleus of children showing abnormal perinatal and neurodevelopmental parameters. At ROC analysis, the best prognostic ADC cut-off value was 1.535 mm2/s × 10−6 (sensitivity 80%, specificity 86%) in the right frontal white matter. ADC1 > ADC0 in the right visual cortex and left dentate nucleus, positively correlated with multiple abnormal perinatal and neurodevelopmental parameters. The van Rooij score was significantly higher in children presenting with sleep disorders. Conclusions: ADC values could be used as prognostic biomarkers to predict children’s neurodevelopmental outcomes. Further studies are needed to address these crucial topics and validate our results. Early and multidisciplinary perinatal evaluation and the subsequent re-assessment of children are pivotal to identify physical and neuropsychological disorders to guarantee early and tailored therapy.

Imaging of Hypoxic-Ischemic Injury (in the Era of Cooling)

Hypoxic-ischemic injury (HII) is a major worldwide contributor of term neonatal mortality and long-term morbidity. At present, therapeutic hypothermia is the only therapy that has demonstrated efficacy in reducing severe disability or death in infants with moderate to severe encephalopathy. MRI and MRS performed during the first week of life are adequate to assess brain injury and offer prognosis. Patterns of injury will depend on the gestation age of the neonate, as well as the degree of hypotension.

Cerebral perfusion changes of the basal ganglia and thalami in full-term neonates with hypoxic-ischaemic encephalopathy: a three-dimensional pseudo continuous arterial spin labelling perfusion magnetic resonance imaging study

BACKGROUND

Neonatal hypoxic-ischemic encephalopathy (HIE) is one of the common causes of neurological injury in full-term neonates following perinatal asphyxia. The conventional magnetic resonance technique has low sensitivity in detecting variations in cerebral blood flow in patients with HIE.

OBJECTIVE

This article evaluates the clinical diagnostic value of three-dimensional pseudo-continuous arterial spin labelling (3-D pcASL) perfusion magnetic resonance imaging (MRI) for early prediction of neurobehavioral outcomes in full-term neonates with HIE.

MATERIALS AND METHODS

All neonates diagnosed with HIE underwent MRI (conventional and 3-D pcASL perfusion MRI). Cerebral blood flow values were measured in the basal ganglia (caudate nuclei, lenticular nuclei), thalami and white matter regions (frontal lobes, corona radiata). After 1-month follow-up, the Neonatal Behavioral Neurological Assessment scores were used to divide patients into favourable outcome group versus adverse outcome group.

RESULTS

Twenty-three patients were enrolled in this study. There were no statistical differences between the symmetrical cerebral blood flow values of bilateral basal ganglia, thalami and white matter regions. However, the cerebral blood flow values of grey matter nuclei were higher than the white matter regions. The average value of cerebral blood flow in the basal ganglia and thalami in the adverse outcome group was 37.28±6.42 ml/100 g/min, which is greater than the favourable outcome group (22.55 ± 3.21 ml/100 g/min) (P<0.01). The area under the curve (AUC) of 3-D pcASL perfusion MRI was 0.992 with a cutoff value of 28.75 ml/100 g/min, with a Youden's index of 0.9231. The sensitivity and specificity were 92.3% and 100%, respectively.

CONCLUSION

The 3-D pcASL demonstrated higher perfusion alteration in the basal ganglia and thalami of neonatal HIE with adverse outcomes. The 3-D pcASL perfusion MRI has the potential to predict neurobehavioral outcomes of neonates with HIE.

Hypoglycemia in Infants with Hypoxic-Ischemic Encephalopathy Is Associated with Additional Brain Injury and Worse Neurodevelopmental Outcome

OBJECTIVE

To determine the incidence of hypoglycemia among infants with hypoxic-ischemic encephalopathy (HIE) who received therapeutic hypothermia, and to assess whether infants with hypoglycemia had more brain injury on magnetic resonance imaging (MRI) or differences in neurodevelopmental outcome.

STUDY DESIGN

Single-center, retrospective cohort study including infants cooled for HIE. Hypoglycemia (blood glucose <36.0 mg/dL <2 hours and <46.8 mg/dL ≥2 hours after birth) was analyzed in the period before brain MRI. Brain injury was graded using a validated score. Motor and neurocognitive outcomes were assessed at 2 years for all survivors, and 5.5 years for a subset who had reached this age.

RESULTS

Of 223 infants analyzed, 79 (35.4%) had hypoglycemia. MRI was performed in 187 infants. Infants with hypoglycemia (n = 65) had higher brain injury scores (P = .018). After adjustment for HIE severity, hypoglycemia remained associated with higher injury scores (3.6 points higher; 95% CI, 0.8-6.4). Hyperglycemia did not affect MRI scores. In survivors at 2 years (n = 154) and 5.5 years (n = 102), a univariable analysis showed lower 2-year motor scores and lower motor and cognitive scores at preschool age in infants with hypoglycemia. After adjustment for HIE severity, infants with hypoglycemia had 9 points lower IQs (P = .023) and higher odds of adverse outcomes at preschool age (3.6; 95% CI, 1.4-9.0).

CONCLUSIONS

More than one-third of infants cooled for HIE had hypoglycemia. These infants had a higher degree of brain injury on MRI and lower cognitive function at preschool age. Strategies to avoid hypoglycemia should be optimized in this setting.

The role of MRI-based texture analysis to predict the severity of brain injury in neonates with perinatal asphyxia

OBJECTIVE

To evaluate the efficacy of the MRI-based texture analysis (TA) of the basal ganglia and thalami to distinguish moderate-to-severe hypoxic-ischemic encephalopathy (HIE) from mild HIE in neonates.

METHODS

This study included 68 neonates (15 with mild, 20 with moderate-to-severe HIE, and 33 control) were born at 37 gestational weeks or later and underwent MRI in first 10 days after birth. The basal ganglia and thalami were delineated for TA on the apparent diffusion coefficient (ADC) maps, T₁-, and T₂ weighted images. The basal ganglia, thalami, and the posterior limb of the internal capsule (PLIC) were also evaluated visually on diffusion-weighted imaging and T₁ weighted sequence. Receiver operating characteristic curve and logistic regression analyses were used.

RESULTS

Totally, 56 texture features for the basal ganglia and 46 features for the thalami were significantly different between the HIE groups on the ADC maps, T₂-, and T₂ weighted sequences. Using a Histogram_entropy log-10 value as >1.8 from the basal ganglia on the ADC maps (p < 0.001; OR, 266) and the absence of hyperintensity of the PLIC on T₁ weighted images (p = 0.012; OR, 17.11) were found as independent predictors for moderate-to-severe HIE. Using only a Histogram_entropy log-10 value had an equal diagnostic yield when compared to its combination with other texture features and imaging findings.

CONCLUSION

The Histogram_entropy log-10 value can be used as an indicator to differentiate from moderate-to-severe to mild HIE.

ADVANCES IN KNOWLEDGE

MRI-based TA may provide quantitative findings to indicate different stages in neonates with perinatal asphyxia.

Quantitative Susceptibility Mapping of the Basal Ganglia and Thalamus at 9.4 Tesla

The thalamus (Th) and basal ganglia (BG) are central subcortical connectivity hubs of the human brain, whose functional anatomy is still under intense investigation. Nevertheless, both substructures contain a robust and reproducible functional anatomy. The quantitative susceptibility mapping (QSM) at ultra-high field may facilitate an improved characterization of the underlying functional anatomy in vivo. We acquired high-resolution QSM data at 9.4 Tesla in 21 subjects, and analyzed the thalamic and BG by using a prior defined functional parcellation. We found a more substantial contribution of paramagnetic susceptibility sources such as iron in the pallidum in contrast to the caudate, putamen, and Th in descending order. The diamagnetic susceptibility sources such as myelin and calcium revealed significant contributions in the Th parcels compared with the BG. This study presents a detailed nuclei-specific delineation of QSM-provided diamagnetic and paramagnetic susceptibility sources pronounced in the BG and the Th. We also found a reasonable interindividual variability as well as slight hemispheric differences. The results presented here contribute to the microstructural knowledge of the Th and the BG. In specific, the study illustrates QSM values (myelin, calcium, and iron) in functionally similar subregions of the Th and the BG.

Neuroimaging in the term newborn with neonatal encephalopathy

Neuroimaging is widely used to aid in the diagnosis and clinical management of neonates with neonatal encephalopathy (NE). Yet, despite widespread use clinically, there are few published guidelines on neuroimaging for neonates with NE. This review outlines the primary patterns of brain injury associated with hypoxic-ischemic injury in neonates with NE and their frequency, associated neuropathological features, and risk factors. In addition, it provides an overview of neuroimaging methods, including the most widely used scoring systems used to characterize brain injury in these neonates and their utility as predictive biomarkers. Last, recommendations for neuroimaging in neonates with NE are presented.

Precision Medicine in Neonates: A Tailored Approach to Neonatal Brain Injury

Despite advances in neonatal care to prevent neonatal brain injury and neurodevelopmental impairment, predicting long-term outcome in neonates at risk for brain injury remains difficult. Early prognosis is currently based on cranial ultrasound (CUS), MRI, EEG, NIRS, and/or general movements assessed at specific ages, and predicting outcome in an individual (precision medicine) is not yet possible. New algorithms based on large databases and machine learning applied to clinical, neuromonitoring, and neuroimaging data and genetic analysis and assays measuring multiple biomarkers (omics) can fulfill the needs of modern neonatology. A synergy of all these techniques and the use of automatic quantitative analysis might give clinicians the possibility to provide patient-targeted decision-making for individualized diagnosis, therapy, and outcome prediction. This review will first focus on common neonatal neurological diseases, associated risk factors, and most common treatments. After that, we will discuss how precision medicine and machine learning (ML) approaches could change the future of prediction and prognosis in this field.

Neuroimaging of Basal Ganglia in Neurometabolic Diseases in Children

Diseases primarily affecting the basal ganglia in children result in characteristic disturbances of movement and muscle tone. Both experimental and clinical evidence indicates that the basal ganglia also play a role in higher mental states. The basal ganglia can be affected by neurometabolic, degenerative diseases or other conditions from which they must be differentiated. Neuroradiological findings in basal ganglia diseases are also known. However, they may be similar in different diseases. Their assessment in children may require repeated MRI examinations depending on the stage of brain development (mainly the level of myelination). A large spectrum of pathological changes in the basal ganglia in many diseases is caused by their vulnerability to metabolic abnormalities and chemical or ischemic trauma. The diagnosis is usually established by correlation of clinical and radiological findings. Neuroimaging of basal ganglia in neurometabolic diseases is helpful in early diagnosis and monitoring of changes for optimal therapy. This review focuses on neuroimaging of basal ganglia and its role in the differential diagnosis of inborn errors of metabolism.

Increased Use of Therapeutic Hypothermia in Infants with Milder Neonatal Encephalopathy due to Presumed Perinatal Asphyxia

INTRODUCTION

Adverse outcomes have been reported in infants with mild neonatal encephalopathy (NE). Increasing clinical experience with the application of therapeutic hypothermia (TH) may have resulted in the treatment of newborns with milder NE during recent years.

OBJECTIVE

To determine whether infants treated with TH in the initial years following implementation had a higher degree of NE than infants treated during subsequent years.

METHODS

Infants with NE treated with TH from February 2008 until July 2017 were included. Thompson and Sarnat scores, amplitude-integrated electroencephalography (aEEG) background patterns before the start of TH, and neurodevelopmental outcome at 2 years were compared between infants treated from February 2008 until October 2012 (period 1) and infants treated from November 2012 until July 2017 (period 2).

RESULTS

211 newborns with NE were treated with TH (period 1: n = 109, period 2: n = 102). Sarnat scores in period 1 and 2 were mild in 7.3 vs. 28.4%, moderate in 66.1 vs. 44.1%, and severe in 26.6 vs. 22.5%, respectively (p = 0.008). Thompson scores were lower in period 2 (median = 9, IQR 7-12) than in period 1 (median = 10, IQR 8.5-13.5, p = 0.018). The aEEGs and neurodevelopmental outcomes were comparable between the periods.

CONCLUSIONS

Based on Thompson and Sarnat scores, but not aEEG background patterns, infants treated during the second period had milder NE than infants treated during the first years following implementation of TH. There was no difference in 2 years neurodevelopmental outcome. Further research is necessary to evaluate the value of TH for infants with clinically mild NE.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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