In vivo assessment of blood flow patterns in abdominal aorta of mice with MRI: implications for AAA localization.

Abdominal aortic aneurysms (AAA) localize in the infrarenal aorta in humans, while they are found in the suprarenal aorta in mouse models. It has been shown previously that humans experience a reversal of flow during early diastole in the infrarenal aorta during each cardiac cycle. This flow reversal causes oscillatory wall shear stress (OWSS) to be present in the infrarenal aorta of humans. OWSS has been linked to a variety of proatherogenic and proinflammatory factors. The presence of reverse flow in the mouse aorta is unknown. In this study we investigated blood flow in mice, using phase-contrast magnetic resonance (PCMR) imaging. We measured blood flow in the suprarenal and infrarenal abdominal aorta of 18 wild-type C57BL/6J mice and 15 apolipoprotein E (apoE)-/- mice. Although OWSS was not directly evaluated, results indicate that, unlike humans, there is no reversal of flow in the infrarenal aorta of wild-type or apoE-/- mice. Distensibility of the mouse aortic wall in both the suprarenal and infrarenal segments is higher than reported values for the human aorta. We conclude that normal mice do not experience the reverse flow in the infrarenal aorta that is observed in humans.