Geometric variability of the abdominal aorta and its major peripheral branches

Vessel geometry determines blood flow dynamics and plays a crucial role in the pathogenesis of vascular disease. In vivo assessment of three-dimensional (3D) vessel anatomy is vital to improve the realism of arterial flow model geometries and investigate factors associated with the localisation of atherosclerosis. The quantification of vascular geometry is also particularly important for the proper design and preclinical testing of endovascular devices used to treat peripheral arterial disease. The purpose of this study was to quantitatively evaluate the intersubject variability of 3D branching and curvature of the abdominal aorta and its major peripheral arteries. Contrast-enhanced renal MRA scans of healthy abdominal vessels obtained in 12 subjects (8 men, 4 women mean age 49 years, range 27-84 years) were segmented, and smoothed centerlines were determined as descriptors of arterial geometry. Robust techniques were employed to characterise non-planar vessel curvature, arterial taper, and 3D branching parameters. Noticeable 3D curvature and tapering were quantified for the proximal anterior visceral and renal branches. Mean 3D branching angles of 63.5+/-10.1 degrees and 73.1+/-6.8 degrees were established for the right and left renal arteries, respectively. Angles describing the ostial position and initial trajectory of the renal arteries confirmed the antero-lateral origin and direction of the right and the more lateral orientation of the left. The anterior visceral branches emerged predominantly from the left side of the anterior aortic wall. Branching parameters determined at the aortic bifurcation demonstrated mild asymmetry and non-planarity at this location. In summary, the results from this study address the scarcity of available in vivo 3D quantitative geometric data relating to the abdominal vasculature and reflect the geometric variability in living subjects.