Morphology and hemodynamics of large arteries using phase-contrast magnetic resonance imaging to assess cardiovascular pathology

According to the World Health Organization, heart disease accounted for 30% of all deaths in 2005, killing an estimated 17.5 million people. One particularly challenging aspect of researching and assessing cardiovascular pathology is the non-invasive interrogation of time-resolved morphologic and hemodynamic flow parameters. The directional patterns of blood flow are central in the ability to understand and assess clot formation, arterial compliance, arterial morphology, after-load, and ultimately patient treatment and disease outcome. With this in mind, this thesis uses the spatial and temporal velocity fields measured by phase-contrast magnetic resonance imaging (PC-MRI) to quantify the hemodynamics in two clinically relevant pathologies - specifically focusing on viscous wall shear stress (WSS) forces at the artery lumen.;In-vitro spatial velocity field validations using Poiseuille and unsteady Womersley flow phantoms found excellent agreement between theory and experiment, averaging a root-mean-square error (RMSE) of approximately 2.2 cm/s for all phantom models. An unsteady Womersley flow phantom modeled after a pediatric right pulmonary artery measured WSS with an RMSE of 1.3 dynes/cm2. This validated methodology was clinically applied to quantify WSS in the large arteries of bicuspid aortic valve (BAV) and pulmonary arterial hypertension (PAH) patients.;PC-MRI showed that the spatial distribution and magnitude of systolic WSS in the aorta of BAV patients (n=15, averaging -6.7+/-4.3 dynes/cm 2) differs significantly from control patients (n=15, averaging -11.5+/-6.6 dynes/cm2, P=0.03). The BAV and control group also showed a significant difference between the positional WSS at systole (minimum P<0.001). Linear regression analysis determined that shear range index (r=0.77, P<0.001), regurgitant fraction (r=0.68, P<0.001), and WSS at systole (r=0.66. P<0.001) showed a significant correlation to aorta dilation.;For the PAH patients, ANCOVA found the rate of PAH dilatation (n=10) was 250% the rate of the controls (n=10) and highly significant (0.81 vs. 0.33 mm/year, P<0.001). Peak systolic flow was found to be correlated to age for both populations (P<0.001) with no difference between populations (P=0.55). WSS was found to decrease significantly with age in the PAH population (P=0.02). The quantification of WSS may be useful for cellular level structure-function research of BAV and PAH.