Differential Perfusion Patterns of Perforator and Random Flaps Assessed by Indocyanine Green Imaging

Background: Indocyanine green angiography (ICGA) is widely used to evaluate flap perfusion in reconstructive surgery, but the optimal timing for assessment may differ by flap type. This study compared perfusion dynamics of perforator and random pattern flaps in a rat model using ICGA. Methods: ICGA dynamics were compared between perforator and random flaps in a rat model. Sixteen Sprague–Dawley rats (275–300 g) were randomly assigned to either a perforator or a random flap group. A 0.25 mg dose of indocyanine green(ICG) was administered via the femoral vein, and fluorescence images were acquired at predefined intervals over 4 minutes. Hypoperfusion was defined as fluorescence intensity below 30% of the peak value. Necrosis was assessed on postoperative day 7. Statistical analyses included the Mann–Whitney U and log-rank tests with EMICM modeling. Results: In the perforator flap group, the final area of necrosis corresponded to the ICGA-defined perfusion boundary observed between 10 and 50 seconds post-injection. In contrast, necrosis in the random flap group aligned with the ICGA-defined perfusion boundary captured between 30 and 150 seconds. The most accurate time points for necrosis prediction were 50 seconds for perforator flaps and 150 seconds for random flaps, both demonstrating statistical significance (p = 0.0028). Conclusion: ICGA timing requirements differ between flap types. Implementing flap-specific assessment windows may enhance intraoperative interpretation and reduce false-positive findings. These findings support the development of flap-specific ICGA protocols to improve intraoperative decision-making in reconstructive surgery.