An important consideration in the design of cardiovascular biomaterials is the prevention of thrombus formation when exposed to blood. Thrombus formation is initiated by the activation of coagulation factor XII (FXII) to FXIIa leading to thrombin formation and activation of platelets. Thrombi formed under blood flow are complex structures of blood coagulation factors, cellular components, and fibrin fibers. In the case of vascular grafts, thrombi invade the graft lumen and reduce blood flow. For many decades, thrombosis has been assessed using a chronic arteriovenous shunt implant in a non-human primate model. It has been used to study novel and clinically approved medications, novel and clinically-used vascular devices, and combinations of medications and devices. With this established technique data is collected to quantify platelet accumulation over time as well as endpoint fibrin accumulation. While this provides a reliable and quantifiable metric for assessing thrombus formation, it does little to elucidate the physical characteristics of the thrombus including size and feature morphology. This information would be particularly useful when evaluating new biomaterials designed to inhibit thrombus formation. To better assess thrombus structure, we have developed a technique using microCT to quantify luminal volume of a variety of vascular graft biomaterials. Additionally, we correlated luminal volume to platelet and fibrin quantities to allow translation of this work to broader applications.