This pilot device trial aims to test the feasibility of using photoacoustic images to monitor tissue perfusion and to guide post-surgical wound treatment. Through this pilot study, the investigators will test the feasibility, identify any practical issues, and acquire essential information (e.g., drop-off rate, variation in wound healing rate) to guide future large-scale studies.

This pilot device trial aims to test the feasibility of using photoacoustic images to monitor tissue perfusion and to guide post-surgical wound treatment. Through this pilot study, the investigators will test the feasibility, identify any practical issues, and acquire essential information (e.g., drop-off rate, variation in wound healing rate) to guide future large scale studies.

For recruited patients, wound care will be guided by both photoacoustic imaging and Kent imaging, a multi-spectral imaging technique for tissue oxygenation mapping. None of the techniques is currently used in the clinic as standard care.

Inclusion Criteria:

• Patients with a chronic wound on the foot that is presumed to be due to arterial insufficiency.

Exclusion Criteria:

• Patients with a massive deep tissue infection.
• Patients with preexisting skin conditions, such as melanoma, psoriasis, in areas close to the wound(s).
• Noncompliant patients who do not adhere to care plans.
• Pregnant women.
• Adults unable to consent.