Correlation between Indocyanine Green Fluorescence Angiography and Laser Speckle Contrast Imaging in a Flap Model.

Background: Indocyanine green fluorescence angiography (ICG-FA) is used to assess tissue intraoperatively in reconstructive surgery. This requires an intra-venous dye injection for each assessment. This is not necessary in laser speckle contrast imaging (LSCI); therefore, this method may be better suited for tissue evaluation. To determine this, we compared the two methods in a porcine flap model.
Methods: One random and one pedicled flap were raised on each buttock of six animals. They were assessed with LSCI at baseline, when raised (T ₀ ), at 30 minutes (T ₃₀ ) and with ICG-FA at T ₀ and T ₃₀ . Regions of interest (ROI) were chosen along the flap axis. Perfusion, measured as perfusion units (PU) in the LSCI assessment and pixel-intensity for the ICG-FA video uptake, was calculated in the ROI. Correlation was calculated between PU and pixel-intensity measured as time to peak (TTP) and area under curve for 60 seconds (AUC ₆₀ ).
Results: Correlation between LSCI and AUC ₆₀ for the ICG-FA in corresponding ROI could be seen in all flaps at all time points. The correlation was higher for T ₀ (r=0.7 for random flap and r=0.6 for pedicled flap) than for T ₃₀ (r=0.57 for random flap and r=0.59 for pedicled flap). Even higher correlation could be seen PU and TTP (T ₀ : random flap r=-0.8 and pedicled flap r=0.76. T ₃₀ : random flap r=-0.8 and pedicled flap r=0.71).
Conclusion: There is a correlation between PU from LSCI and TTP and AUC ₆₀ for ICG-FA, indicating that LSCI could be considered for intraoperative tissue assessment.
Competing Interests: The authors have no financial interest to declare in relation to the content of this article. Disclosure statements are at the end of this article, following the correspondence information.
(Copyright © 2023 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of The American Society of Plastic Surgeons.)