[Diagnostic imaging of brain maturation in premature infants].

In 3 studies brain maturation in 42 preterm infants with no or minor cerebral deviations was examined with MRI. With a scoring system 5 stadia in gyral development were recognized, which corresponded to the gestational age (duration of amenorrhoea of the pregnant woman). At a gestational age between 30 and 34 weeks, myelin was present in many brain stem, diencephalic and cerebellar structures, but only in a few hemispheric structures. Little progress in myelination was noticed up to the gestational age of 46 weeks. Remnants of the germinal matrix formed a sharp contrast with the immature unmyelinated periventricular white matter and had a characteristic appearance on MR images before term age. Broad periventricular zones with subtle change of signal intensity were also physiological in this age group. Zones with more outspoken signal intensity change compared with the rest of the cerebral white matter were, however, not physiological and represent mild ischaemic change of the periventricular white matter.