Tissue perfusion in DIEP flaps using Indocyanine Green Fluorescence Angiography, Hyperspectral imaging, and Thermal imaging

Flap necrosis still occurs in skin free flap autologous breast reconstruction. We investigated the benefit of Indocyanine Green Angiography (ICGA) using quantitative parameters for the objective, peri-operative evaluation of flap perfusion. In addition, we investigated the feasibility of hyperspectral (HSI) and thermal imaging (TI) for postoperative flap monitoring.A single-center, prospective observational study was performed in 15 patients undergoing deep inferior epigastric perforator (DIEP) flap breast reconstruction (n=21). DIEP flap perfusion was evaluated with ICGA, HSI and TI using a standardized imaging protocol. The ICGA perfusion curves and derived parameters, HSI extracted oxyhemoglobin (oxyHb) and deoxyhemoglobin (deoxyHb) values and flap temperatures were analyzed and correlated to clinical outcomes.Post-hoc quantitative analysis of intraoperatively collected data of ICGA application correctly distinguished between adequately and insufficiently perfused DIEP flaps. ICG perfusion curves identified a lack of arterial inflow (n=2) and occlusion of the venous outflow (n=1). In addition, a postoperatively detected partial flap epidermolysis could have been predicted based on intraoperative quantitative ICGA data. During postoperative monitoring, HSI identified impaired perfusion areas within the DIEP flap based on deoxyHb levels. The results of this study showed a limited added value of TI.Quantitative, post-hoc analysis of ICGA data produces objective and reproducible parameters that enable the intraoperative detection of arterial and venous congested DIEP flaps. HSI appeared to be a promising technique for postoperative flap perfusion assessment. A diagnostic accuracy study is needed to investigate ICGA and HSI parameters in real-time and to demonstrate a clinical benefit.