A Prospective Comparative Study of Color Doppler Ultrasound and Infrared Thermography in the Detection of Perforators for Anterolateral Thigh Flaps.

Background: Preoperative localization of the perforators allows precise planning of the flap design and improves surgical efficiency. Recently, infrared thermography is introduced as a reliable alternative, where the perforator corresponds to the "hot spot" on the thermogram. This study aims to compare the application of color Doppler ultrasound (CDU) and infrared thermography in preoperative perforator mapping of the anterolateral thigh (ALT) perforator flap.
Patients and Methods: From September 2017 to January 2019, CDU and infrared thermography were both applied on 20 patients to locate the perforators originated from lateral circumflex femoral artery preoperatively. The perforators identified using each modality were marked on the anterolateral thigh region. The accuracy of both mapping methods was analyzed according to the intraoperative findings. The relation between location bias and the thickness of subcutaneous tissue was analyzed.
Results: A total of 20 ALT flaps were included. Fifty-three perforators were detected by CDU, and 51 "hot spots" were identified by infrared thermography, in which 50 "hot spots" corresponded to CDU, and the consistency test showed that the κ index was 0.712 (P < 0.05), representing high consistency. The infrared thermography has a sensitivity of 94.3% and a specificity of 85.7% compared with CDU. The deviation between thermal imaging and CDU was positively correlated with the thickness of the subcutaneous tissue. The Pearson correlation coefficient was 0.84 (R = 0.84). Forty-four perforators marked by CDU were selected for designing the flap. Anatomical findings showed that the accuracy rate of CDU and infrared thermal was 93.2% (41 of 44) and 86.3% (38 of 44), respectively. There was no statistical difference (P > 0.05).
Conclusions: Compared with CDU, infrared thermography can be used to locate perforators, in this case, the ALT perforators, with a high degree of consistency. It is portable, economical, noninvasive, and easy to operate. It has higher accuracy in patients with thinner subcutaneous tissue. We believe that infrared thermography can be a useful technique for perforator mapping, especially in patients where the subcutaneous tissue is thinner.