An In-Vivo Structural MRI Investigation of Newborn Infants’ Brains: Preterm Infants and Infants born with Intrauterine Growth Restriction

Atkinson, Jessica
An In-Vivo Structural MRI Investigation of Newborn Infants’ Brains: Preterm Infants and Infants born with Intrauterine Growth Restriction. PhD thesis, University of Liverpool.

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Introduction: It is well documented that preterm infants are less developed than term infants at term age and infants with IUGR are said to be of higher vulnerability. Fractional Anisotropy (FA) and Apparent Diffusion Coefficient (ADC) are sensitive to micro structural abnormalities and increases in anisotropy associated with premyelination are the earliest indications of the beginning processes of myelination. Furthermore reductions in brain volumes have been found in preterm infants compared to controls and IUGR infants. Thyroxine (T4) is necessary for normal growth and development of the central nervous system. Infants born preterm miss out on the maternal transfer of T4 that occurs during the third trimester and are born with an underdeveloped thyroid gland that is not yet producing sufficient amounts of T4. Method: Sixty nine infants (51 preterm, 9 IUGR and 9 controls) were imaged on a 1.5 Telsa MRI Scanner. DTI analysis was performed using medical imaging software (DTIstudio). FA and ADC maps were used to draw regions of interest around the posterior limb of the internal capsule (PLIC), corpus callosum (CC), frontal lobes (FL) and occipital lobes (OL). The software Brain Voyager QX (version 1.9.10) was used for image realignment and demarcation of T2 Weighted images and the images were analysed using medical imaging software for structure- specific brain volume measurements (Easymeasure). Statistical analysis was conducted with repeated measures ANOVA using SPSS version 18. Results: A significant interaction when investigating anterior vs. posterior structures and laterality of structures with treatment in the frontal lobes and posterior limb of the internal capsule was found suggesting a group difference between infants treated with levothyroxine and those receiving placebo. IUGR infants generally had lower FA and ADC than the control group. Generally lower structural volumes were found in the placebo and IUGR group. Conclusion: Administration of levothyroxine affects the structures on different sides of the brain differently and raises structural volumes. Levothyroxine may be of particular benefit to infants with low levels of thyroxine in their blood (hypothyroxinemia) and male preterm infants. Preterm infants born with intrauterine growth restriction are of higher vulnerability than appropriate for gestational age preterm infants with lower FA, higher ADC and lower structural volumes. Further research is required to fully explore asymmetries in the preterm and IUGR brain and should look at administering levothyroxine to infants with low levels of thyroxine in their blood.

Item Type: Thesis (PhD)
Additional Information: Date: 2012-09 (completed)
Depositing User: Symplectic Admin
Date Deposited: 17 Apr 2015 14:37
Last Modified: 17 Dec 2022 01:26
DOI: 10.17638/02002304