MAGNETIC-RESONANCE-IMAGING OF THE BRAIN IN PREMATURE-INFANTS DURING THE NEONATAL-PERIOD - NORMAL PHENOMENA AND REFLECTION OF MILD ULTRASOUND ABNORMALITIES

An MRI study was performed in 34 preterm infants who were clinically a nd neurologically normal and whose cranial ultrasound revealed no or o nly mild abnormalities. The postconceptional age at MRI varied between 30.6 and 37 weeks. The purpose of the study was to evaluate the signi ficance of periventricular changes in signal intensity on MRI, compari ng MRI with ultrasound. T-1-weighted and T-2-weighted images were asse ssed for changes in signal intensity of the periventricular white matt er relative to the remainder of the cerebral hemispheric white matter. Cerebral MRIs of 13 postterm infants were additionally investigated. In all preterm infants small localized areas of high signal intensity on T-1-weighted images and low signal intensity on T-2-weighted images were seen adjacent to the frontal horns of the lateral ventricles. Th ey faded with increasing age and were no longer seen one month after t erm in the group of postterm infants. The areas were considered normal before term age and probably represent remnants of the germinal matri x. Periventricular echodensities corresponded with a zone of changed s ignal intensity within the periventricular white matter on MRI. MRI si gnal change correlated with the presence and location of echodensities ; the MRI signal changes slowly faded away after the echodensities dis appeared.