Evaluation of Hemodynamics in a Murine Hindlimb Ischemia Model Using Spatial Frequency Domain Imaging.

BACKGROUND AND OBJECTIVES Spatial frequency domain imaging (SFDI), an optical imaging technique capable of quantitatively measuring tissue hemodynamics over a large field-of-view, has captured the interest of scientists and clinicians due to its ability to image rapidly and noninvasively. The goal of this study was to apply SFDI in a preclinical murine model to assess its ability to measure hemodynamic changes due to hindlimb ischemia in vivo longitudinally. STUDY DESIGN/MATERIALS AND METHODS Complete unilateral femoral artery ligation was performed on a total of nine C57BL/6J mice to induce ischemia in the left hindlimb. Changes in vascular perfusion in each mouse were monitored through SFDI acquisition of both the ischemic and control limbs throughout the course of 4 weeks. High-frequency pulsed-wave Doppler ultrasound was also acquired to confirm occlusion of the left femoral artery post-ligation compared with the control limb, while histological analysis was used to quantify femoral artery lumen shape and size. RESULTS Tissue oxygen saturation in the ischemic limb normalized to the control limb decreased from a ratio of 0.96 ± 0.06 at baseline to 0.86 ± 0.10 at day 1, then 0.94 ± 0.06 at day 3, followed by 0.95 ± 0.14 at day 7, 0.91 ± 0.09 at day 14, 0.90 ± 0.09 at day 21, and 1.01 ± 0.09 at day 28. CONCLUSION The results of this study indicate the utility of SFDI to detect hemodynamic changes in a preclinical murine model, as well as how to effectively use this tool to extract information regarding ischemia-induced hindlimb changes. In our model, we observed a decline in tissue oxygen saturation within one day post-ischemic injury, followed by a return to baseline values over the 4-week study period. While reducing skin artifacts and modifying camera hardware could still improve this murine imaging approach, our multimodality study presented here suggests that SFDI can be used to reliably characterize ischemia-mediated changes in a clinically relevant mouse model of peripheral arterial disease. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.