Delineation of Ascending Aortic Medial Degeneration using Diffusion Tensor Imaging
Abstract
Thoracic aortic aneurysms (TAAs) are a life-threatening dilation of the thoracic aorta that can lead to catastrophic dissection or rupture. In TAAs, the structure of the aortic wall is perturbed. Current imaging approaches assess lumen dimensions but lack the ability to delineate aortic wall architecture, a key determinant of aortic integrity. Diffusion tensor imaging (DTI) is an MRI modality which can reveal tissue microstructure through diffusion characteristics. In this thesis I investigated the potential for DTI to evaluate TAA architecture. A porcine model of aortic wall degeneration was developed, and DTI scans were performed on healthy and degenerated porcine ascending aortas. Here, DTI scalar indices correlated with histological markers of aortic damage. Subsequently, DTI assessment of human ascending aortic aneurysms revealed that abnormalities in DTI scalar indices correlated with medial degeneration including regional cellularity and regional glycosaminoglycan deposition.