The Application Of Transrectal Ultrasound In Evaluation Of The Efficacy Of Neoadjuvant Therapy For Rectal Cancer

ObjectiveTo explore the value of transrectal ultrasound(TRUS),endorectal elastography and contrast-enhanced ultrasound(CEUS)in evaluation of the efficacy of neoadjuvant therapy for rectal cancer.Methods1.A total of 42 patients with advanced rectal cancer who underwent neoadjuvant therapy(NET)were involved.All patients had undergone transrectal ultrasound(TRUS)examinations before and after NET in our hospital between November 2013 and January2016.The tumor was evaluated for its TN-staging,size,morphological character,echo pattern,internal vascularity and the distance of tumor from the anal and as well as depth of invasion and relationship with surrounding tissues and.Color Doppler flow imaging was employed to detect tumor peak systolic velocity(PSV)and resistance index(RI).A series of parameters examined by US were compared and the correlation between TRUS TN-staging with tumor stages by postoperative pathology and preoperative magnetic resonance imaging(MRI)was investigated.2.42 patients with advanced rectal cancer who underwent neoadjuvant therapy(NET)had undergone ultrasonic elastography and contrast-enhanced ultrasound(CEUS)examinations baced on TRUS before and after NET.By using software on the workstation;the region of interest(ROI)of tumor was manually drawn on elastography and contrast ultrasonographic images.The tumor was evaluated for its elastic scores,strain ratio with normal intestinal wall tissue and parameters of CEUS.The relevant parameters were compared before and after NET.Results1.(1)The accuracy of TRUS for T2,T3,T4 tumors was respectively 88.9%(8/9),78.3%(18/23)and 60.0%(6/10)and the overall accuracy of restaging TRUS for T-stage was 73.8%(32/42,Kappa=0.616,P=0.000).The accuracy of TRUS for N0,N+tumors was respectively 72.0%(18/25)and 58.8%(10/17)and the overall accuracy of restaging TRUS for N-stage was 66.7%(28/42,Kappa=0.308,P=0.046).(2)the overall accuracy of MRI for T-stage and N-stage was respectively 78.6%(33/42)、 64.3%(27/42).The difference in accuracy between restaging TRUS and MRI was no statistical significance.(3)Anteroposterior diameter of rectal tumors detected by TRUS was lower after NET and the difference was significant(t=-6.13,P<0.001).RI and PSV of rectal tumors were less statistically significant higher after NET compared with those before NET(t=1.32,P=0.257;t=1.53,P=0.200)2.The SR of rectal tumors in elastography ultrasonographic images was statistically significant lower after NET(t=-24.92,P<0.001).Hardness scoring of rectal tumors detected by TRUS was also lower after NET than that before NET but the difference was not significant(t=-1.714,P=0.121).PI and AUC were lower after NET and the differences were significant(t=-9.66,P=0.001;t=-13.58,P<0.001).However,the changes of AT and TTP were no statistical significance(t=-1.17,P=0.307;t=-1.26,P=0.275)Conclusions1.The accuracy of restaging TRUS and MRI for T-stage was high,but the accuracy of either of them in predicting N-stage was low without reaching clinical requirements and combination of TRUS,MRI and other imaging technology may be needed forcomprehensive evaluation.2.PSV and RI can provide more qualitative and quantitative information for efficacy evaluation of NET and they are valuable for choice of treatment.3.Ultrasound elastography conferred different pathological periods of rectal tumors according to the changes of SR between tumors and normal intestinal tissue before and after NET and it may be an assistant method to CEUS for efficacy evaluation of NET.4.CEUS can can reveal the vasoganglion and quantitatively reflect perfusion status of rectal cancer.CEUS has potential clinical application value in clinical treatment and dose adjustmen and it is valuable for evaluation of clinical prognosis.