RSNA: MR spectroscopy reveals false start of white matter maturation in preterm infants

CHICAGO—Premature birth may trigger developmental processes in the white matter (WM) of the brain that could put children at a higher risk for problems later in life, according to a study to be presented at the annual meeting of the Radiological Society of North America (RSNA).

Preterm infants, who are born 23 to 36 weeks after conception rather than the normal 37 to 42 week time period, have an increased risk of behavioral problems such as impulsiveness, distractibility, autism, and attention deficit disorder.

With approximately 500,000 preterm births per year in the United States, about 60,000 are at risk for significant long-term problems.

Stefan Blüml, PhD, director of the New Imaging Technology Lab at Children’s Hospital Los Angeles and associate professor of research radiology at the University of Southern California in Los Angeles, and colleagues executed a study in which the metabolism of white and grey matter at equivalent post-conceptional (PC) age in term and preterm infants were compared.

The brain’s WM transmits signals and enables communication between different parts of the brain. Gray matter (GM), on the other hand, is the part of the brain that processes and sends out signals. Though WM damage is visible on structural MRI, Blüml and colleagues utilized magnetic resonance spectroscopy (MRS) to examine the differences on a microscopic level. MRS measures concentrations of key chemicals in living tissue, such as those that are involved in membrane synthesis, energy metabolism, and neural transmission.

“By monitoring the concentrations of these key chemicals, we are able to open up a window into what is happening inside living cells during development in the brains of prematurely born infants,” Blüml told Health Imaging.

The researchers compared the concentrations of certain chemicals associated with mature white and gray matter in 51 full-term and 30 preterm infants. Though the study group had normal MRI findings, MRS results revealed significant differences in the biochemical maturation of WM between the term and preterm infants. This discovery indicates that the processes of WM maturation, like axonal growth and possibly myelination, are affected by premature birth.

Blüml and colleagues believe this false start in WM development is triggered by events after birth. When in utero, the fetus’s brain is exposed to very low levels of oxygen because our brains have evolved to optimally develop in a low oxygen environment. When infants are born, they are exposed to an increased level of oxygen for which preterm babies might not be ready.

“Our findings show that even in the infants with otherwise ‘unremarkable’ MRIs, the biochemical profile of key metabolites associated with axonal development, energy metabolism and membrane synthesis is altered,” Blüml remarked. “That is to say, even in the infants whose MRIs show no outward evidence of abnormality, these data suggest that cellular processes supporting brain development may be altered.”

Though the alteration in oxygen environments may cause irregularities in WM development, the newborn brain is capable of re-wiring itself, known as plasticity. This ability allows the brain to control new skills over the duration of development and makes the brains of preterm infants and children more responsive to therapeutic interventions, particularly when the issues have been identified early.

Therapeutic interventions aimed to alleviate possible adverse impacts of prematurity on brain function may need to emphasize strategies that prevent a “false start” of WM maturation, the authors said.

It is important to note that this research is in its initial stages. The study’s authors are currently partnering with families who have preterm children to monitor their development for further insight on the brain development of preterm babies and its potential influence on future behavioral problems.