Evaluation Of Tumor Marginal And Central Microvessels In Neoadjuvant Therapy For Rectal Cancer By Transrectal Double Contrast-enhanced Ultrasonography

Objective: 1.To investigate the distribution of blood vessels in the margin and center of rectal cancer by double contrast-enhanced transrectal ultrasound(DCEUS).2.To explore the clinical value of tumor margin and center in neoadjuvant therapy(NET)for rectal cancer by DCEUS.Methods: 1.A retrospective analysis was made on 75 patients with rectal cancer confirmed by pathology in the first affiliated Hospital of Guangxi Medical University from September 2018 to November 2019.DCEUS was used to investigate the distribution of blood vessels in the margin and center of rectal cancer.All patients were examined by DCEUS within 7 days before operation or neoadjuvant therapy.The enhancement modes of UCA at the edge and center of the tumor were compared by two experienced ultrasound doctors according to the microvascular imaging of ultrasound contrast agent(UCA),including the intensity of enhancement,the speed of perfusion and the speed of clearance.The Toshiba CHI-Q software system configured with the instrument was started to quantitatively analyze the edge and center of rectal cancer,and the time-intensity curves(TIC)and corresponding parameters were obtained.The main parameters include: time to peak(TTP),peak intensity(PI),mean transit time,(MTT),slope,area under the curve(AUC).Each image was analyzed repeatedly for 3 times,and the average value of each quantization parameter was taken for 3 times.The tumor edge of rectal cancer was compared with the central DCEUS parameters.2.20 patients with rectal cancer who received neoadjuvant therapy were selected,and the tumor edge and central DCEUS parameters of rectal cancer were compared before and after neoadjuvant therapy with the same method.Results: 1.By comparing the marginal and central DCEUS features of 75 patients with rectal cancer,it was found that the marginal area of rectal cancer had stronger enhancement intensity,faster contrast medium perfusion and faster clearance than the central region,and the difference was statistically significant(P<0.05).2.By comparing the quantitative parameters of DCEUS between the tumor margin and the center of 75 patients with rectal cancer,it was found that the parameters of PI,Slope and AUC in the tumor margin of rectal cancer were higher than those in the center of the tumor,while the MTT parameters were less than those in the center of the tumor,and the difference was statistically significant(P<0.05).The TTP parameter in the margin of rectal cancer was less than that in the center of the tumor,but the difference was not statistically significant(P>0.05).3.By comparing the characteristics of tumor margin and central DCEUS in 20 cases of rectal cancer before and after neoadjuvant therapy,it was found that the enhancement intensity,perfusion rate and clearance rate of tumor margin and center of rectal cancer decreased after neoadjuvant therapy,and the difference was statistically significant(P<0.05).4.By comparing the DCEUS parameters of tumor margin in 20 cases of rectal cancer before and after neoadjuvant therapy,it was found that PI,Slope and AUC parameters decreased and MTT parameters increased after neoadjuvant therapy,and the difference was statistically significant(P<0.05);The TTP parameter decreased,but the difference was not statistically significant(P>0.05).5.By comparing the central DCEUS parameters of 20 cases of rectal cancer before and after neoadjuvant therapy,it was found that the PI and Slope parameters of rectal cancer decreased after central neoadjuvant therapy,and the difference was statistically significant(P<0.05).The AUC parameters decreased,while the TTP and MTT parameters increased,but the difference was not statistically significant(P>0.05).6.By comparing the changes of DCEUS quantitative parameters in 20 cases of rectal cancer before and after neoadjuvant therapy,it was found that the PI and AUC parameters in the tumor margin of rectal cancer were significantly different from those in the center of the tumor after neoadjuvant therapy(P< 0.05).There was no significant difference in TTP,MTT and Slope parameters between the tumor margin of rectal cancer and before and after central neoadjuvant therapy(P>0.05).Conclusion: 1.DCEUS can noninvasively understand the distribution of blood vessels in the margin and center of rectal cancer;2.DCEUS can noninvasively evaluate the effect of neoadjuvant therapy for rectal cancer and provide quantitative basis for timely adjustment of treatment plan,which has potential clinical value;3.DCEUS can compare the difference of sensitivity between tumor margin and central neoadjuvant therapy of rectal cancer,and provide key observation area for neoadjuvant therapy of rectal cancer.