Aim: The aim of this magnetic resonance imaging (MRI) study is to study white matter abnormalities (WMA) in a 3-year cohort of extremely low gestational age (ELGA) infants.

Methods: 109 ELGA infants (<27 weeks 0 days) underwent MRI (Philips Intera 1.5T) at term-equivalent age. Diffusion tensor imaging (DTI, 15 directions) data of high quality were acquired in 54 infants. 16 term born healthy control infants were scanned according to the same protocol. Images were analysed using a scoring system for WMA. Apparent diffusion coefficient (ADC) and factional anisotropy were measured in the “total” white matter at the level of the centrum semiovale and in the corpus callosum.

Results: Mean gestational age was 25 weeks 4 days (23 weeks 1 day to 26 weeks 6 days). 86% of infants had no or mild WMA and 14% had moderate or severe WMA. 56% of the preterm infants had diffuse excessive high signal intensities (DESHI). DESHI infants had higher mean ADC (p<0.01) and lower factional anisotropy (p<0.001) in the “total” white matter compared with controls. No significant differences in diffusion were seen in infants without DESHI compared with controls. The morbidity was higher in infants with DESHI. The ELGA infants had significantly altered diffusion in the corpus callosum compared with controls.

Conclusion: We have obtained MRI–DTI in a cohort of ELGA infants. Only 14% had moderate or severe WMA, which is consistent with our previous report. On the other hand we found a high incidence of DESHI, predominantly in the sickest infants. In the DESHI regions aberrations in diffusion were seen, indicating altered white matter organisation. Neurodevelopmental follow-up is ongoing.