Value of the combination of a smartphone-compatible infrared camera and a hand-held doppler ultrasound in preoperative localization of perforators in flaps

This study was conducted to evaluate the effectiveness of the FLIR ONE PRO, a thermal imaging camera for smartphones, combined with handheld Doppler (HHD) in the localization of perforator arteries and to assess the efficacy of the FLIR ONE PRO in distinguishing perforators of the descending branch of the lateral circumflex femoral artery (LCFA) from other perforators of the anterolateral thigh perforator (ALTP) flap. We enrolled 29 free perforator flaps from 22 patients in our study. Before surgery, dynamic infrared thermography was performed using a FLIR ONE PRO to visualize hotspots on the flaps. Subsequently, HHD was used to further determine the perforators under the hotspots, which were ultimately identified and confirmed through intraoperative findings. Additionally, infrared images of the ALTP flap were analyzed using FLIR Tools. The performances of the FLIR ONE PRO and FLIR ONE PRO + HHD groups were evaluated by comparing the intraoperative findings. Using FLIR ONE PRO + HHD, 119 hotspots and 106 perforators were identified during surgery. Using FLIR ONE PRO + HHD, sensitivity and positive predictive value were 97.87% and 88.46%, respectively, in the young (age≤45 years). In the elderly group (age>45 years), these percentages were 93.22% and 82.09%, respectively. In addition, we found that the FLIR ONE PRO could be useful for differentiating perforators in the descending branch of the LCFA from other perforators within 5 min. The results showed a sensitivity of 96.15%, a specificity of 98.9%, a positive predictive value of 96.15%, and a negative predictive value of 98.9%. Compared to using FLIR ONE PRO alone, the combined application of HHD and FLIR ONE PRO had a higher value in perforator localization by increasing the positive predictive value. The FLIR ONE PRO may have significance in the rapid prediction of perforators deriving from the descending branch of the LCFA.