Magnetic resonance imaging assessment of brain maturation in preterm neonates with punctate white matter lesions

Abstract

Early white matter (WM) injury affects brain maturation in preterm infants as revealed by diffusion tensor imaging and volumetric magnetic resonance (MR) imaging at term postmenstrual age (PMA). The aim of the study was to assess quantitatively brain maturation in preterm infants with and without milder forms of WM damage (punctate WM lesions, PWML) using conventional MRI. Brain development was quantitatively assessed using a previously validated scoring system (total maturation score, TMS) which utilizes four parameters (progressive myelination and cortical infolding, progressive involution of glial cell migration bands and germinal matrix tissue). PWML were defined as foci of increased signal on T1-weighted images and decreased signal on T2-weighted images with no evidence of cystic degeneration. A group of 22 preterm infants with PWML at term PMA (PWML group) were compared with 22 matched controls with a normal MR appearance. The two groups were comparable concerning gestational age, birth weight and PMA. TMS was significantly lower in the PWML group than in the control group (mean TMS 12.44 +/- 2.31 vs 14.00 +/- 1.44; P = 0.011). Myelination (mean 2.76 +/- 0.42 PWML group vs 3.32 +/- 0.55 control group, P = 0.003) and cortical folding (3.64 +/- 0.79 vs 4.09 +/- 0.43, P = 0.027) appeared to be significantly delayed in babies with PWML. Conventional MRI appears able to quantify morphological changes in brain maturation of preterm babies with PWML; delayed myelination and reduced cortical infolding seem to be the most significant aspects.