Elasticity and geometry measurements of vascular specimens using a high-resolution laboratory CT scanner

Vascular diseases are frequently associated with changes in the mechanical properties of the arterial wall. Existing techniques for studying arterial geometry and mechanical properties in vitro are often destructive, since they involve sectioning of the specimen into strips, or provide average measurements of the mechanical properties over the volume of intact specimens. We developed a high-resolution computed tomography (CT) scanner for in vitro studies of arterial geometry and static elastic properties. The x-ray image intensifier based system can acquire single transverse images, or a volume image, with 2 mm-1 resolution. Images were obtained through an intact abdominal aortic aneurysm at five pressures. The incremental circumferential Young's modulus E(inc) was calculated from the internal and external circumferences, and at physiological pressures E(inc) of the aneurysm was found to be 275 times greater than that of the normal aorta proximal to it. A volume image of the specimen provided landmarks that allowed histological sections to be obtained at locations coincident with those where the elasticity was measured. The histological analysis revealed a sixfold decrease in elastin content in the aneurysm, compared to the normal aorta. We have demonstrated that the static mechanical properties and geometry of vascular specimens can be quantified in vitro with the new high-resolution CT scanner and can be compared subsequently with histological analysis to provide further insight into the understanding of atherogenesis.