Volumetric brain MR helps evaluate premature babies

Volumetric MR images show that neonatal therapies designed to help premature babies survive and thrive could help offset brain injuries associated with premature birth.

Results from research performed at Royal Children's Hospital in Melbourne, Australia, emphasize that parental nuturing can reduce postpartum white matter injury and lower the babies' susceptibility to cognitive and motor diseases such as cerebral palsy. The study also suggests that radiologists will play a role in predicting the outcomes of these cases, according to principal investigator Dr. Terrie Inder, an associate professor of pediatric medicine.

The results show that the stress of spending the first days of life in a neonatal intensive care unit affects babies' frontal brain regions, especially the extent and reversibility of white matter damage. Tender loving care in the form of more cuddling and other positive interactions with parents soon after birth improves the baby's behavior and brain structure, Inder said.

Better treatment strategies for sepsis and blood pressure control, which appear to be the main direct causes of white matter injury, should be addressed, she said.

Volumetric MRI mapped the neuroanatomic characteristics of 202 preterm infants with a mean gestational age of 28 weeks, as well as 36 full-term babies. Overall, the preterm infants had an average of 25 cc less total cerebral tissue than did the fullterm babies, according to Deanne K. Thompson, a research associate, who presented the results at the International Society for Magnetic Resonance in Medicine meeting in May.

The premature babies had significantly reduced basal ganglia or subcortical gray matter and less cerebrospinal fluid, she said.

Perinatal factors contributing to reduced total brain tissue volume in preterm infants included the number of days on total parenteral nutrition and intrauterine growth restriction. Increases in CSF volumes were related to gestational age and the amount of white matter injury.

The presence and severity of cerebral white matter injury were a major predictor of preterm tissue volume, Thompson said. Moderate to severe white matter injury resulted in a significant reduction in cortical gray matter in preterm infants compared with no or mild white matter injury.

The sensorimotor region displayed the largest changes in cortical gray matter. Gestational age, hours on positive pressure ventilation, and intrauterine growth restriction predicted how much cortical gray matter would be measured in this region.

The dorsal prefrontal region displayed changes in cortical gray matter, with intrauterine growth restriction as a contributor, but the unmyelinated white matter showed no clear perinatal correlates.

The parieto-occipital area revealed substantial differences between pre-term and full-term infants for cortical gray matter, but again with no clear perinatal correlates. In contrast, the premotor area was reduced in unmyelinated white matter. Male gender was a significant contributor.

The Melbourne group plans to release additional data indicating that quantitative MRI can be used to predict the outcome of extremely premature neonatal patients.

"Depending on what a radiologist says about what the brain looks like at term, the pediatrician will have the capability to predict the baby's developmental outcomes at two years of age," Inder said.