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Title: The unstable carotid plaque and brain ischaemia : non-invasive detection, pathophysiological and clinical implications
Author: Altaf, Nishath
ISNI:       0000 0004 2668 6805
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2008
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The aim of this thesis was to test the hypothesis that the detection of plaque haemorrhage by Magnetic Resonance Imaging (MRI PH+) is a clinical valid biomarker of unstable carotid disease in patients with symptomatic high grade carotid disease. This hypothesis was tested by a series of studies in patients with symptomatic high grade stenosis including a comparison of MRI PH+ to histological assessment of plaque instability, and an examination of the relationships between MRI PH+ and cerebral ischaemia as assessed by microembolisation, cerebral white matter hyperintense lesions (WMHL), diffusion weighted cerebral imaging (DWI) and clinical assessment. MRI PH+ carotid plaques were associated with features of active plaque disease, including inflammation. The senstiviity and specificity of MRI PH+ to detect spontaneous and intra-operative microembolic signals (detected by transcranial Doppler) was high (85 and 83%) and moderate (51 and 54%), respectively. Cerebral WMHL were found to be more prevalent (mean number [S.D.]: 3.3[3.3] vs. 2.1[2.5]) and larger (mean volume [S.D.]: 10.3[9.3] vs. 7.0[6.6] ml) in hemispheres ipsilateral to MRI PH+ rather than MRI PH- carotid plaques. MRI PH+ increased the risk of developing cerebral DWI ischaemic lesions (odds ratio 6.2; 95% C.I. 1.7-21.8) and were associated with multiple lesions of different ages. MRI PH + symptomatic carotid plaques increased the short-term risk of ipsilateral ischaemic neurological events with a hazard ratio of 5.9 (95% C.I. 1.4- 25.6); but not in the contralateral, asymptomatic side. This work has demonstrated that MRI PH is a potential valid biomarker of plaque instability in patients with symptomatic carotid stenosis. Further studies are required to se if risk stratification can be improved using other plaque features and improved localization of plaque haemorrhage.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available