title: Validation of a brain MRI relaxometry protocol to measure effects of preterm birth at a flexible postnatal age.
abstract: BACKGROUND
  Magnetic resonance imaging (MRI) is a useful tool to study brain growth and organization in preterm neonates for clinical and research purposes, but its practicality can be limited by time and medical constraints. The aim of this study was to determine if MRI relaxometry of the deep nuclei, as opposed to white matter, would reflect the influence of gestational age at birth on structures essential to motor development, regardless of postnatal age at the time of imaging.
  
  
  RESULTS
  This was a prospective observational study of infants without brain injury on conventional neuroimaging who were cared for in the neonatal intensive care unit (NICU) at Vanderbilt. Infants were studied using MRI relaxometry within a 2-month window of postmenstrual term age. In 45 infants, white matter MRI T1 relaxation times were influenced by both gestational age and postnatal age at imaging time (R(2) = 0.19 for gestational age vs. R(2) = 0.34 adjusting for both gestational age and age at imaging; all p < 0.01). Similar results were obtained with T2 relaxation times. In contrast, globus pallidus T1 reflected gestational age but was minimally affected by postnatal age (R(2) = 0.50 vs. 0.57, p < 0.001).
  
  
  CONCLUSIONS
  The results obtained using this imaging protocol are consistent with the slow maturation of the globus pallidus, essential to normal development of complex motor programs into adulthood. Globus pallidus MRI relaxometry measures the impact of gestational age at birth on brain development independent of postnatal age in preterm infants and should prove useful for predictive modeling in a flexible time-window around postmenstrual term age.
authors.affiliation: Department of Pediatrics, Vanderbilt University, Nashville, TN, USA. nathalie.maitre@vanderbilt.edu.
authors.forename: Nathalie L
authors.initials: NL
authors.lastname: Maitre
authors.forename: James C
authors.initials: JC
authors.lastname: Slaughter
authors.forename: Ann R
authors.initials: AR
authors.lastname: Stark
authors.forename: Judy L
authors.initials: JL
authors.lastname: Aschner
authors.forename: Adam W
authors.initials: AW
authors.lastname: Anderson
mesh_terms: D005260:Female; D005865:Gestational Age; D005917:Globus Pallidus / Q000254:growth & development*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000254:growth & development*; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D047928:Premature Birth; D011446:Prospective Studies; D011699:Putamen / Q000254:growth & development*; D066127:White Matter / Q000254:growth & development*