Fractional anisotropy in white matter tracts of very-low-birth-weight infants

Abstract

Background Advances in neonatal intensive care have not yet reduced the high incidence of neurodevelopmental disability among very-low-birth-weight (VLBW) infants. As neurological deficits are related to white-matter injury, early detection is important. Diffusion tensor imaging (DTI) could be an excellent tool for assessment of white-matter injury. Objective To provide DTI fractional anisotropy (FA) reference values for white-matter tracts of VLBW infants for clinical use. Materials and methods We retrospectively analysed DTI images of 28 VLBW infants (26-32 weeks gestational age) without evidence of white-matter abnormalities on conventional MRI sequences, and normal developmental outcome (assessed at age 1-3 years). For DTI an echoplanar sequence with diffusion gradient (b=1,000 s/mm 2 ) applied in 25 non-collinear directions was used. We measured FA and apparent diffusion coefficient (ADC) of different whitematter tracts in the first 4 days of life. Results A statistically significant correlation was found between gestational age and FA of the posterior limb of the internal capsule in VLBW infants (r=0.495, P<0.01). Conclusion Values of FA and ADC were measured in white-matter tracts of VLBW infants. FA of the pyramidal tracts measured in the first few days after birth is related to gestational age.

Young adults born preterm with very low birth weight demonstrate widespread white matter alterations on brain DTI

“…These results are in accordance with results from Dudink et al (2007), who found correlation between gestational age and FA in the posterior limb of the internal capsule in VLBW infants, but found no correlation between MD and gestational age.…”

“…When studied at term, preterm infants with mechanical ventilation for more than 2 days had significant decreases in FA in the genu of corpus callosum (Anjari et al, 2009). Significant correlation has also been found between gestational age at birth and FA in the posterior part of the internal capsule at term equivalent age (Anjari et al, 2009;Dudink et al, 2007), and between FA and birth weight and gestational age in the external/extreme capsule, corpus callosum and fornix in adolescents (12-17 years) (Nagy et al, 2009). These previous studies together with our results demonstrate that the WM areas with deranged microstructure associated with low birth weight, low gestational age, and mechanical ventilation are the same at birth and in early adulthood.…”

Neuroimaging of cortical development and brain connectivity in human newborns and animal models

“…During normal brain development, the ADC of the white matter was shown to decrease together with a steady increase in anisotropy (Huppi et al 1998a;Neil et al 1998;Dudink et al 2007). Following a hypoxic-ischemic injury, ADC also decreases, resulting in values that are much reduced compared with the age-and region-dependent normal values (Rutherford et al 2004;McKinstry et al 2002b).…”

Contributions of Diffusion-Weighted Imaging to Fetal and Neonatal Imaging

“…In particular, anisotropy is highest and mean diffusivity is lowest in the commissural pathways, followed by projectional and association pathways. 39,41 In addition, anisotropy is higher and mean diffusivity is lower in the primary motor pathway compared to that in the primary sensory pathway. 38 The rate of increase in anisotropy occurring between 28 and 43 weeks is more rapid in subcortical portions of projectional pathways compared to the deep, more compact parts of projectional pathways.…”