Lumley, Guy (2011) Quantitative functional magnetic resonance imaging in cerebral small vessel disease. Masters thesis, University of Liverpool.
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Introduction: Cerebral small vessel disease (cSVD) is an important, but relatively poorly understood cause of both lacunar strokes and vascular dementia. Structural magnetic resonance imaging (MRI) markers of cSVD, including lacunes, white matter lesions (WML) and microbleeds, have been shown not to correlate consistently with clinical severity, as gauged by cognitive decline, and might offer little more than endpoint markers of disease. However, alternative developing MR techniques, including functional MRI (fMRI) using the blood-oxygen-level-dependent (BOLD) signal, offer a promising approach to charting disease severity. Aims: The primary aim is to determine whether ‘n’, a measure of neurovascular coupling (NVC) which underpins interpretation of the BOLD signal, differs between patients with cSVD and healthy matched controls. If ‘n’ does differ, a secondary aim is to determine whether ‘n’ correlates with tests of cognitive function. Methods: Eleven patients with cSVD and sixteen age-, education- and gender-matched healthy controls were recruited. Participants underwent a battery of cognitive tests focused upon executive functions and a series of MRI scans. These included structural scans, arterial spin labelling (ASL) to measure cerebral blood flow and BOLD signal. Oxygen calibrated fMRI was used with a modified Stroop Interference Task. Results: The cSVD group performed worse on the digit symbol substitution test (DSST) (p = 0.00005) than the control group. There was a significantly different BOLD response in 11 regions between patient and control groups, which were aggregated into frontal, parietal, motor, insular and total regions. ‘n’ was reduced across total regions (p = 0.02) in the patient group. ‘M’ was increased in the patient group and correlated inversely with ‘n’. DSST did not correlate with ‘n’ in patients. Conclusion: The results suggest an uncoupling of the neurovascular response in patients with cSVD, possibly associated with an increase in the oxygen extraction fraction. A larger sample size would be needed to investigate whether altered neurovascular coupling might highlight at-risk subjects who have not yet had a stroke.
|Item Type:||Thesis (Masters)|
|Subjects:||R Medicine > R Medicine (General)|
|Departments, Research Centres and Related Units:||Academic Faculties, Institutes and Research Centres > Faculty of Medicine > School of Clinical Sciences|
|Deposited On:||22 May 2012 11:26|
|Last Modified:||06 Aug 2012 09:25|
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