Meta-analysis of apparent diffusion coefficients in the newborn brain

Area of Science:

• Neuroimaging
• Neonatal Neurology
• Quantitative MRI

Background:

• Hypoxic-ischemic injury (HII) is a major cause of neonatal brain damage.
• Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) mapping are sensitive to HII severity.
• Establishing normative ADC values is crucial for accurate HII assessment in term newborns.

Purpose of the Study:

• To establish normative apparent diffusion coefficient (ADC) values in the term newborn brain.
• To compare normative ADC values with those in newborns with hypoxic-ischemic injury (HII) and varying outcomes.
• To identify specific brain regions and their ADC values indicative of HII severity and prognosis.

Main Methods:

• A meta-analysis of 14 reports was conducted.
• Apparent diffusion coefficient (ADC) measurements were stratified by tissue type, distribution, and specific anatomic structures.
• Normative ADC values were compared between healthy term newborns, HII newborns with good outcomes, and HII newborns with poor outcomes.

Main Results:

• Normative ADC values showed white matter > gray matter = cerebellum, with regional variations (e.g., lowest in posterior limb of internal capsule, highest in frontal/occipital white matter).
• No significant ADC differences were found between normative and good-outcome HII groups.
• Poor-outcome HII groups exhibited significantly lower ADC values across multiple brain regions compared to normative data.

Conclusions:

• This meta-analysis provides a basis for normative apparent diffusion coefficient (ADC) values in the term newborn brain.
• Deviations from normative ADC values, particularly in the poor outcome group, highlight pathologies associated with neurologic sequelae.
• Quantitative ADC analysis aids in assessing HII severity and predicting neurological outcomes in neonates.