Application Of The B-flow Technique In Preoperative Localization Of Perforater Flap

Objective:To clarify the advantages of B-flow versus CDFI and whether B-flow can replace CEUS in the preoperative positioning of perforator flaps.Then to construct B-flow method for detecting flap perforation vessels and to explore the application of this method.Methods:Of 30 patients who underwent flap transplantation in our hospital,B-flow,B-flow enhanced,CDFI and CEUS were used to detect the number of perforator vessels in the donor site of the flap before surgery.According to the inner diameter,path,peak systolic velocity(PSV),resistance index(RI)and other indicators of the perforator vessels,the optimal perforator vessels were selected.Four models were used to detect the number of small blood vessels in the fat layer of the optimal perforator vessel region.Finally,the optimal perforator vessel was used as the core combined with the fat layer blood flow perfusion,and the flap size and shape were designed before surgery.The times taken using CDFI and B-flow to detect perforating vessels were recorded before surgery,and the differences between the two modes were compared.The differences between the four groups of the four modes used to detect the number of perforator vessels in the flap donor area and the number of small blood vessels in the fat layer were compared;afterwards,the pairwise comparison differences between groups were analyzed.CDFI and B-flow were used to locate and mark the optimal perforator vessel point for the perforator flap before surgery.During the operation,the distance to the actual puncture point was measured separately and counted as the AC value and BC value to compare the difference between AC and BC.The effects of BMI on the number of perforator vessels displayed by CDFI and B-flow and the AC value and BC value were tested.A total of 30 flaps were designed before surgery in 30 patients.The size range was2.1 cm×2.5cm～16.0cm×12.3cm.A total of 30 flaps were removed during the operations.The removed skin flap contained 1 or 2 perforator vessels.Taking the intraoperative results as the gold standard,we compared the diagnostic consistency and diagnostic efficiency between the four modes of B-flow,B-flow enhanced,CDFI and CEUS.Results:1.B-flow takes less time than CDFI(t=12.721,P<0.05).2 B-flow,B-flow enhanced,CDFI and CEUS showed significant differences in detecting perforator vessels in the donor site of the flap(χ~2=62.799,P<0.05).The results of pairwise comparison were as follows:B-flow enhanced and CEUS>B-flow>CDFI(all P<0.05),and there was no significant difference between CEUS and B-flow enhanced in detecting perforating vessels(P>0.05).3.B-flow,B-flow enhanced,CDFI and CEUS showed significant differences in detecting small blood vessels in the fat layer(χ~2=80.071,P<0.05).The results of pairwise comparison were as follows:B-flow enhanced>CEUS>B-flow and CDFI(all P<0.05),and there was no significant difference between B-flow and CDFI in detecting small blood vessels in the fatty layer(P>0.05).4.The BC value was lower than the AC value(t=3.328,P<0.05),suggesting that the B-flow positioning was more accurate.5.The pairwise correlations between the BMI,the number of perforator vessels displayed by CDFI,the number of perforator vessels displayed by B-flow,the AC value and the BC value were tested by the Spearman correlation:There was a negative correlation between BMI and the number of perforator vessels displayed by CDFI(r=-0.458,P<0.05).There was a negative correlation between BMI and the number of perforator vessels displayed by B-flow(r=-0.572,P<0.01).There was a positive correlation between the BMI and AC values(r=0.791,P<0.01).There was no correlation between BMI and BC(r=0.055,P>0.05).6.Taking the intraoperative result as the gold standard,all of the models had better diagnostic consistency,and B-flow had the best diagnostic consistency(kappa:0.93).All of the four modes had better diagnostic effectiveness,and B-flow had the best diagnostic efficiency(Sensitivity:100.00%,specificity:92.00%,positive predictive value:94.44%,negative predictive value:100.00%,Youden index:0.92,accuracy:96.61%).Conclusion:1.B-flow is better than CDFI in detecting perforator vessels,and the localization of B-flow is more accurate.2.B-flow is not as good as CEUS in detecting perforator vessels.However,the diagnostic consistency and diagnostic efficiency of B-flow are better than those of CEUS.In addition,B-flow has the advantages of noninvasiveness,low price,simple implementation and others.Therefore,B-flow technology is recommended for the preoperative localization of perforator flaps.3.B-flow enhanced shows better blood flow perfusion in the fat layer than CEUS,and this method has great research value and application potential.