A validated clinical MRI injury scoring system in neonatal hypoxic-ischemic encephalopathy

Abstract

Background: Deep nuclear gray matter injury in neonatal hypoxic-ischemic encephalopathy (HIE) is associated with worse neurodevelopmental outcomes. We previously published a qualitative MRI injury scoring system utilizing serial T1-weighted, T2-weighted and diffusion-weighted imaging (DWI), weighted for deep nuclear gray matter injury.

Objectives: To establish the validity of the MRI scoring system with neurodevelopmental outcome at 18-24 months.

Materials and methods: MRI scans from neonates with moderate to severe HIE treated with therapeutic hypothermia were evaluated. Signal abnormality was scored on T1-weighted, T2-weighted and DWI sequences and assessed using an established system in five regions: (a) subcortical: caudate nucleus, globus pallidus and putamen, thalamus and the posterior limb of the internal capsule; (b) white matter; (c) cortex, (d) cerebellum and (e) brainstem. MRI injury was graded as none, mild, moderate or severe. Inter-rater reliability was tested on a subset of scans by two independent and blinded neuroradiologists. Surviving infants underwent the Bayley Scales of Infant and Toddler Development-III (Bayley-III) at 18-24 months. Data were analyzed using univariate and multivariate linear and logistic regression.

Results: Fifty-seven eligible neonates underwent at least one MRI scan in the first 2 weeks of life. Mean postnatal age at scan 1 was 4±2 days in 50/57 (88%) neonates and 48/54 (89%) surviving infants underwent scan 2 at 10±2 days. In 54/57 (95%) survivors, higher MRI injury grades were significantly associated with worse outcomes in the cognitive, motor and language domains of the Bayley-III.

Conclusion: A qualitative MRI injury scoring system weighted for deep nuclear gray matter injury is a significant predictor of neurodevelopmental outcome at 18-24 months in neonates with HIE.

Keywords: Brain; Hypoxic-ischemic encephalopathy; Magnetic resonance imaging; Neonates; Neurodevelopmental outcome; Scoring system.

Fig. 1

Examples of MRI regional scores. a T1-W image score of bilateral globus pallidus/putamen injury (2+2=4) (T1 score=4) (arrows indicate regions of globus pallidus/putamen injury) in a 9-day-old girl (gestational age of 40 weeks). b T2-W image score of bilateral globus pallidus/putamen injury (2+2=4) and bilateral cortical injury (1+1=2) (T2 score=6) (arrows indicate regions of globus pallidus/putamen and cortical injury) in an 11-day-old girl (gestational age 40 weeks)). c Diffusion-weighted MRI image of bilateral restriction in the white matter (1+1=2) (DWI score=2) (arrows indicate regions of white matter injury) in a 5-day-old girl (gestational age of 38 weeks). d T2-W image score of unilateral cerebellar injury (1) (T2 score=2) (arrow indicates region of cerebellar injury) in a 1-day-old girl (gestational age of 36 weeks). e T1-W image score of bilateral global pallidus/putamen (2+2=4) and thalamus injury (2+2=4) (T1 score=8) (arrows indicate regions of globus pallidus/putamen and thalamic injury) in a 10-day-old boy (gestational age of 40 weeks)

Fig. 2

MRI injury score and severity of developmental delay by domain. a Box and whisker plot compares MRI injury score with Bayley-III cognitive domain separated into categories by severity of neurodevelopmental impairment. X-axis displays MRI injury score. Y-axis displays the individual Bayley-III domain neurodevelopmental impairment categories. b Box and whisker plot compares MRI injury score with Bayley-III motor domain separated into categories by severity of neurodevelopmental impairment. X-axis displays MRI injury score. Y-axis displays the individual Bayley-III domain neurodevelopmental impairment categories. c Box and whisker plot compares MRI injury score with Bayley-III language domain separated into categories by severity of neurodevelopmental impairment. X-axis displays MRI injury score. Y-axis displays the individual Bayley-III domain neurodevelopmental impairment categories

Fig. 3

Receiver operator characteristic curve for detecting an adverse outcome using MRI injury score. X-axis displays 1-Specificity. Y-axis displays sensitivity

Fig. 4

MRI injury grade and neurodevelopmental outcomes by domain. a Box and whisker plot compares MRI injury grade with Bayley-III cognitive domain. X-axis displays MRI injury grade. Y-axis displays the individual Bayley-III domain. b Box and whisker plot compares MRI injury grade with Bayley-III motor domain. X-axis displays MRI injury grade. Y-axis displays the individual Bayley-III domain. c Box and whisker plot compares MRI injury grade with Bayley-III language domain. X-axis displays MRI injury grade. Y-axis displays the individual Bayley-III domain