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

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Abstract
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. The authors 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 Einc was calculated from the internal and external circumferences, and at physiological pressures Einc 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.