Intravascular ultrasound and magnetic resonance imaging of atherosclerosis and assessment of endothelial function

Abstract

In this thesis we aimed to investigate the application of IVUS and MRI in assessing plaque and endothelial function in the experimental rabbit model of atherosclerosis. The first experimental chapter focussed on validating the accuracy and reproducibility of mechanical and phased-array IVUS catheter designs in an in-vivo and ex-vivo setting. The second experimental chapter sought to investigate the plaque characterisation technologies of iMAP and VH-IVUS. This was the first time that the two systems had been compared head to head in the experimental rabbit model. The results provided significant and systematic variability in plaque composition analysis with both systems. The third experimental chapter describes an in-vivo investigation between serial endothelial function and vascular remodelling. We have documented that progressive endothelial dysfunction occurs with increasing plaque burden and observed that vascular remodelling in the rabbit experimental model occurs in a way analogous to clinical positive remodelling. In the fourth experimental chapter we described a novel MRI application for the assessment of endothelial function. The MRI endothelial function results were compared against those obtained using IVUS. We have shown MRI to be a viable non-invasive modality for assessing luminal CSA changes in very small calibre vessels in response to vasoactive drugs. The final experimental chapter describes the comparison between MRI and IVUS serial quantifying plaque burden. We concluded that MRI is a feasible non-invasive alternative for imaging atherosclerosis in the experimental rabbit model.