Magnetic resonance imaging of the brain in a cohort of extremely preterm infants

To define magnetic resonance imaging (MRI) appearances of the brain in extr emely preterm infants between birth and term, a sequential cohort of infant s born at a gestational age <30 weeks was studied with a:dedicated neonatal magnetic resonance scanner. Images of infants (n = 41) with a median gesta tional age of 27 weeks (range 23 to 29 weeks) were initially obtained at a median age of 2 days (range 1 to 20 days) and then repeatedly studied; 29 ( 71%) infants had MRI at a median gestational age of 43 weeks (range 38 to 5 2 weeks) (term MRI). On the initial MRI scan 28 of 41 infants had abnormali ties: either intraventricular hemorrhage, germinal layer hemorrhage, ventri cular dilatation, or diffuse and excessive high signal intensity in the whi te matter on T-2-weighted images. When magnetic resonance images for preter m infants at term gestation were compared with those of infants in the cont rol group born at term, 22 of 29 infants had dilatation of the lateral vent ricles, 24 of 29 had squaring of the anterior or posterior horns of the lat eral ventricles, 11 of 29 had a widened interhemispheric fissure or extrace rebral space, and 22 of 29 had diffuse and excessive high signal intensity in the white matter. There were no cases of cystic periventricular leukomal acia. We conclude that MRI abnormalities are commonly seen in the brain of preterm infants on whom images are obtained within 48 hours of birth and th at further abnormalities develop between birth and term. A characteristic a ppearance of diffuse and excessive high signal intensity in the white matte r on TB-weighted images is associated with the development of cerebral atro phy and may be a sign of white matter disease. These MRI appearances may he lp account for the high incidence of neurodevelopmental impairment in extre mely preterm infants.