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Title: Magnetic resonance imaging of the brain following preterm birth
Author: Hart, Anthony Richard
ISNI:       0000 0004 2742 6546
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2011
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Survivors of preterm birth are at high risk of developing neuro-developmental difficulties, but accurate prognostication remains difficult. Magnetic Resonance (MR) imaging can visualise subtle abnormalities in the cerebral white matter better than cranial ultrasound, and provide quantitative markers of brain development, such as apparent diffusion coefficients (ADC) from diffusion-weighted imaging (DWl), and metabolite levels from MR proton spectroscopy (MRS). The neuro-developmental significance of these markers is unclear. Eighty-one infants born under 35 weeks gestational age had MR imaging at term on a 1.5T MR scanner. DWl was obtained in 71 participants, MRS data from the anterior cerebral white matter in 36, and posteriorly in 41. Seventy-seven participants had neuro-developmental follow-up around 18 months corrected age. Review of the first 40 participants' images revealed low inter and intra-observer agreement on the presence of diffuse excessive high signal intensity (DEHSI). No differences in ADC, MRS or outcome scores were noted between participants with and without DEHSI. Overt abnormalities on MR imaging were associated with worse neuro-developmental outcome, but their predictive ability was comparable to cranial ultrasound. ADC values from the cerebral white matter, deep grey matter and cerebellum were not altered in participants with poor outcome. NAA/choline ratios from the posterior periventricular white matter were lower in participants who developed "severe" neuro-developmental difficulties. Combining a NAA/choline ratio of below 0.38 with the appearances of the brain on MR imaging improved its predictive ability. In conclusion, DEHSI, should not be assumed to represent pathology or used for prognostication. MR imaging is not justified in the routine management of preterm infants, and should not replace cranial ultrasound. However, low NAA choline ratios from the posterior periventricular white matter may prove an additional helpful tool in the identification of infants at risk of "severe" neuro-developmental difficulties.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available