Magnetic Resonance Imaging-Based Reference Values for Two-Dimensional Quantitative Brain Metrics in a Cohort of Extremely Preterm Infants

INTRODUCTION

Cerebral magnetic resonance imaging (cMRI) is an important diagnostic tool in neonatology. In addition to qualitative analysis, quantitative measurements may help identify infants with impaired brain growth. This study aimed to create reference values for brain metrics of various brain areas in neonates without major brain injuries born before 28 weeks of gestation.

METHODS

This retrospective study analyzes cMRI imaging data of high-risk patients without severe brain pathologies at term-equivalent age, collected over 4 years since November 2017. Nineteen brain areas were measured, reference values created, and compared to published values from fetal and postnatal MRI. Furthermore, correlations between brain metrics and gestational age at birth were evaluated.

RESULTS

A total of 174 cMRI examinations were available for analysis. Reference values including cut-offs for impaired brain growth were established for different gestational age groups. There was a significant correlation between gestational age at birth and larger "tissue" parameters, as well as smaller "fluid" parameters, including intracerebral and extracerebral spaces.

DISCUSSION

With quantitative brain metrics infants with impaired brain growth might be detected earlier. Compared to preexisting reference values, these are the first of a contemporary collective of extremely preterm neonates without severe brain injuries. Measurements can be easily performed by radiologists as well as neonatologists without specialized equipment or computational expertise.

CONCLUSION

Two-dimensional cMRI brain measurements at term-equivalent age represent an easy and reliable approach for the evaluation of brain size and growth in infants at high risk for neurodevelopmental impairment.

Considerable mortality and morbidity in neonates born below 500 gram

Data evaluating mortality and morbidity in infants born ≤500 g are scarce and show wide variability. To support counselling and decision‐making, we analysed neurodevelopmental outcome in all neonates ≤500 g birth weight.

Retrospective analysis including preterm infants with a birth weight ≤500 g and a gestational age >22 weeks born at a single tertiary perinatal centre between 2010 and 2017.

Of 59 live births, 88% received standard care. Birth weight ranged from 318 to 500 g and gestational age from 23 to 29 weeks. 56% of neonates were born ≤3rd percentile and 42% of treated infants survived. Neurodevelopmental outcome was available in 91% of patients and was evaluated using Bayley Scales of Infant Development at two years. 50% showed a favourable mental development (normal or mild impairment), 75% a favourable motor development and 45% a favourable outcome in both outcome subcategories. When additionally considering visual and hearing disability and, or, cerebral palsy level ≥2 according to the Gross Motor Function Classification System 35% had a good neurodevelopmental outcome.

Survival rate was 37% for all live births and 42% for infants with standard care. More than one‐third of survivors showed no significant neurodevelopmental impairment at two years.