© 2017 Association for Computing Machinery. Many vascular abnormalities, such as aneurysms or stenoses, develop gradually over time. In the early stages of their development, they require monitoring but do not pose sufficient risk to the patient for a clinician to recommend invasive treatment. With a better understanding of the interplay between hemodynamic factors and changes in blood vessel geometry, there is an opportunity to improve clinical care by earlier identification of aneurysms or stenoses with significant potential for further development. Computational fluid dynamics has shown great promise for investigating this interplay and identifying the associated underlying mechanisms, by using patient-derived geometries and modifying them to represent potential evolution of the vascular disease. However, a general, extensible framework for comparing simulation results from different vascular geometries in a direct, quantitative manner does not currently exist. As a first step toward the development of such a framework, we present a method for quantifying the relationship between changes in vascular geometry and hemodynamic factors, such as wall shear stress. We apply this framework to study the correlation between wall shear stress and geometric changes in two opposite settings: When flow properties are associated with consequent changes in the vascular geometry, as in a thoracic aortic aneurysm, and when geometric changes alter the flow, as in a worsening aortic stenosis.