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.

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Background. The preexpanded bipedicled visor flap, supported by the bilateral superficial temporal vessels, stands as an ideal choice for upper and lower lip reconstruction in males. However, the bilateral tissue bridges after flap transfer caused patients significant cosmetic deformity and psychological burden. Early division of bilateral pedicles reduced the length of hospitalization and expenses. In this study, infrared thermography (IRT) was used to guide the early pedicle division after ischemic preconditioning. Methods. This study retrospectively analyzed patients who underwent preexpanded bipedicled visor flap surgery from April 2018 to October 2021. Pedicle division was scheduled at two weeks postflap transfer. Ischemic preconditioning was initiated 3-5 days in advance by repeatedly clamping both pedicles. The temperature alteration of the flap and the temperature difference compared to the normal adjacent tissue were evaluated by IRT. The division surgery was not scheduled until the perfusion assessment indicated adequate. This comprised of subjective examination and indocyanine green angiography. The threshold of temperature difference to determine the pedicle division was analyzed based on the temperature changes between the clamps. Results. A total of 8 male patients successfully conducted the pedicle division without any complications. The delay period after ischemic preconditioning ranged from 14 to 19 days (average 16 days). Through ischemic preconditioning training, the average temperature of the flap gradually increased from 31.85 ± 0.36 °C to 33.89 ± 0.50 °C, and the temperature difference with the normal surrounding tissues decreased from 2.89 ± 0.30 °C to 1.15 ± 0 . 46 ° C (95% confidence interval (1.5, 0.8)). The temperature difference stayed unchanged after pedicle division. Conclusion. Ischemic preconditioning shortens the perioperative period to pedicle division. Monitoring the temperature change reflects the revascularization between the flap and the recipient site, thus guiding the pedicle division. The temperature difference less than 1.5°C after clamping both pedicles can be set as the safe threshold for pedicle division.