Serial Brain MRI in Hospitalized Preterm Infants

Neurological adverse outcomes of very preterm birth can range from severe, including cerebral palsy, hearing and vision impairments, language disorders and learning disability, to less severe, such as developmental coordination disorders, fine motor control deficits, and mild cognitive impairments. While there are numerous factors, such as birth weight, gestational age, interventricular hemorrhage, and bronchopulmonary dysplasia, that have been shown to be associated with neurobehavioral impairments, the underlying neural mechanisms leading to these impairments are not yet understood. In the unit where this study is conducted, the standard of care is that babies born extremely preterm, or those born very preterm with additional clinical risk generally undergo a term equivalent age magnetic resonance imaging (MRI). However, given the limited understanding of the etiology of many neuronal disorders particularly in preterm born infants, findings on these term MRIs can be presented to families with many unanswered questions in terms of causation and implication for future development.

The few previous studies undertaken to better understand the etiology of brain injuries have used longitudinal serial imaging of preterm infants' brain during their NICU stays to look at trajectories of brain structural growth and the development of brain injury. One study found profuse increases in cortical grey matter growth rates that were accompanied by decreases in relative unmyelinated white matter growth rates. Another study found that the most common term equivalent finding associated with preterm birth was diffuse white matter abnormality, although causation and factors associated with these growth alterations and injuries are yet to be fully understood. The main limitation of both serial imaging studies is the limited number of scans per patient that were performed. The average number of scans per infant for both studies was around 2, which often corresponded to one at birth and one at term equivalent age (prior to NICU discharge), and did not provide sufficient information to comprehensively characterize the pattern of brain growth and development in this population.

One study investigated the structure-function relationship in preterm infants between MRI and clinical measures of motor, neurological and neurobehavioral capacity. Researchers found strong associations between the General Movements Assessment, Hammersmith Neonatal Neurological Examination, NICU Neonatal Neurobehavioral Scale, Premie-Neuro, and Test of Infant Motor Performance that correlated with the early and term-equivalent MRI. Based on a review of 88 articles that evaluated sensory-based interventions integrated in the care of very preterm infants in the NICU, nurturing interventions were noted to correlate with improved infant development and lower rates of maternal stress.