Noncontact optical imaging of blood flow and oxygenation distributions in reconstructive skin flaps of rats

Intraoperative fluorescence angiography has been used for predicting mastectomy skin flap necrosis (MSFN), caused by insufficient blood flow and oxygenation. However, several challenging issues limit its wide acceptance in clinical settings, including allergic reactions, short time-window for observation, and high cost for equipment and supplies. We report an inexpensive dye-free multi-wavelength speckle contrast diffuse correlation tomography (MW-scDCT) system that enables continuous and longitudinal imaging of tissue blood flow and oxygenation distributions. We tested it for imaging of 8 rats with different skin flaps (full necrotic, implant, half necrotic, and sham) over 5 days after surgery. In rat skin flaps with implant and full necrosis, blood flow and oxy-hemoglobin concentration decreased while deoxy-hemoglobin concentration increased over 5 days, demonstrating the sensitivity of MW-scDCT in detecting severe tissue ischemia and hypoxia. We are currently testing the MW-scDCT for intraoperative imaging of human mastectomy skin flaps for predicting and preventing MSFN.