The Application Of Dynamic Infrared Thermography For Anterolateral Thigh Perforator Flap Preoperative Perforator Mapping And Intraoperative Monitoring

Objective:To evaluate the application of dynamic infrared thermography(DIRT)for anterolateral thigh perforator(ALTP)Flap preoperative perforator mapping and Intraoperative Monitoring.Analyze its value and provide experience for clinical applications.Methods:Between August 2020 and January 2021,preoperative perforator mapping of free anterolateral thigh perforator flap was performed in 32 patients by three methods:DIRT、CDS and DITR+CDS(using CDS to check and locate perforator branch within the detection range provided by DIRT technique).The examination time of each method was recorded.All of the perforator data were compared with the perforator data in the surgical area intraoperatively.Calculating the sensitivity,positive predictive value of each method.And the identification of the dominant perforator was analyzed for each method.The sensitivity and positive predictive value of the three methods were compared by pair comparison chi-square test,and the examination time was compared by one-way analysis of variance,in which P<0.05 was considered statistically significant.And 13 ALTP flaps were monitored by intraoperative DIRT.The changes of thermal imaging were analyzed.Results:The sensitivity and positive predictive value of DIRT were 78.7%and 94.8%respectively,for CDS 94.7%and 92.3%,and for DIRT combined with CDS 97.2%and 94.6%.The accuracy of identifying the dominant perforator for DIRT was 100%.The sensitivity and positive predictive value of the three methods were tested by χ2 test,respectively.The positive predictive value comparison of the three methods and the sensitivity comparison between CDS and DIRT+CDS showed no statistical difference(P>0.05).The sensitivity comparison between DIRT+CDS and DIRT and between CDS and DIRT was statistically different(P<0.05),indicating that the sensitivity of DIRT+CDS and DIRT+CDS was better than DIRT.A one-way between subjects ANOVA was conducted to compare the examination time of each method,and the difference was statistically significant(P<0.05).It could be considered that the examination time of each method was different:DIRT(14.19±1.33)min,CDS(35.63±2.06)min,DIRT+CDS(29.75±2.52)min,and DIRT<DIRT+CDS<CDS.In all flaps before dividing the flap pedicle and 11 flaps after the vascular anastomosis,the "hot spot" appeared rapidly,and flap general rewarmed.Then more hot spots appeared.After the vascular anastomosis,in 1 flap,the appearance of hot spots was not obviously because of the vascular spasm.In another flap,because of venous thrombosis,the range of hot spot extended,followed by the disappearance of other hot spots after the hot spot appeared.Then the hot spot’s range become narrowed,and the temperature decreased.After the resection and anastomosis of embolized venous,the reperfusion of the flap improved.Conclusion:Although there is a high false positive rate in preoperative positioning of perforator with anterolateral thigh flap by DIRT.However,it can be used as an auxiliary means to reduce the technical difficulty of CDS and provide valuable information for selecting the optimal perforator.When applied to intraoperative monitoring,it can directly reflect the reperfusion of the flap,help to distinguish the arteriovenous crisis of the flap as soon as possible and improve the survival rate of the flap.DIRT is a visual,non-invasive,convenient,economical and portable method,it is easy to promote and apply in primary hospitals.