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Title: Volumetric blood flow and assessment of the metabolic profile of the developing brain in growth restricted fetuses : an ultrasound and proton magnetic resonance spectroscopy study
Author: Story, Lisa
ISNI:       0000 0004 2713 2943
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2011
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Introduction Intrauterine growth restriction (IUGR) is a common obstetric condition causing significant perinatal morbidity and mortality. A phenomenon known as brain sparing occurs in IUGR fetuses whereby blood is preferentially diverted to supply the developing brain often at the expense of other organs. However, although this supposedly neuroprotective mechanism exists, children that were growth restricted in utero have a higher incidence of long term neurodevelopmental sequelae. This thesis therefore aims to explore the brain redistribution phenomenon in detail by investigating cerebral volume blood flow and the metabolic profile of the IUGR brain using high resolution ultrasound and proton magnetic resonance spectroscopy respectively. Methods 150 appropriately grown and 78 IUGR fetuses had volume blood flow assessed longitudinally using high resolution ultrasound and power Doppler in multiple fetal vessels. The metabolic status of the brain was then assessed in 46 appropriately grown and 26 growth restricted fetuses using Proton Magnetic Resonance Spectroscopy. Results IUGR fetuses had a generalised increase in vessel diameter in comparison with appropriately grown control fetuses, and when standardised for weight, increased volume blood flow was noted in the middle cerebral, renal, umbilical and carotid arteries and the ascending aorta. No difference in flow was noted in the descending aorta. N-acetylaspartate:Choline and N-acetylaspartate:Creatine ratios were reduced in IUGR fetuses and lactate was present in the developing brains of both appropriately grown and growth restricted fetuses. Conclusions Volume blood flow is significantly altered in IUGR fetuses, likely to be mediated by alterations in vessel diameter. This may be secondary to alterations in circulating vasoactive factors or as a result in alterations of the composition of vessel walls. The metabolic status of the brain tissue is also altered which may in part explain the higher incidence of neurodevelopmental sequelae in some fetuses that were growth restricted in utero.
Supervisor: Bennett, Phillip ; Rutherford, Mary ; Kumar, Sailesh Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral