Contrast-Enhanced Ultrasound of Mouse Models of Hindlimb Ischemia Reveals Persistent Perfusion Deficits and Distinctive Muscle Perfusion Patterns.

Objective: Mouse models of hindlimb ischemia (HLI) are used to study peripheral arterial disease and evaluate novel therapies. Contrast-enhanced ultrasound (CEUS) is a noninvasive perfusion measurement technique that is increasingly being employed in these models. The objective of this study was to evaluate two models of severe HLI by CEUS to characterize perfusion recovery and muscle perfusion patterns.

Methods: Mice undergoing double femoral artery ligation were measured by CEUS and laser Doppler perfusion imaging (LDPI) at baseline and 1-150 d postsurgery. A second group undergoing femoral artery ligation and excision was measured 1-28 d postsurgery.

Results: By LDPI, both surgeries showed robust perfusion recovery by 14 d postsurgery. However, by CEUS only a ∼40% perfusion recovery plateau was reached in either group. These results are consistent with our previous work, employing a less severe single femoral artery ligation, that showed perfusion in the ischemic limb does not return to normal by 150 d postsurgery. Cluster analysis of muscle perfusion patterns indicated 3-5 different patterns at day 1 postsurgery. The double ligation model yielded significantly less variable perfusion patterns, suggesting that it can provide more reproducible results.

Conclusion: Contrary to LDPI, perfusion as measured by CEUS never fully recovers after hindlimb surgery, even when followed 28-150 d postsurgery. Individual mice can manifest different patterns of muscle perfusion to the same surgery, but these patterns are conserved within and between different surgical techniques. These results may have significant implications for the evaluation of novel therapeutics to treat PAD in mice.