The Application Study Of Transrectal Ultrasound In Assessment Preoperative Staging Of Rectal Cancer

ObjectiveTo evaluate the accuracy of transrectal ultrasound (TRUS)in preoperative staging ofrectal cancer，and to investigate the application value of endorectal elastography andcontrast enhanced ulrasonography (CEUS) in assessment preoperative staging of rectalcancer.MethodsL58patients with rectal cancer were chosen to perform TRUS before surgery topredict TN-staging.The tumor size and resistance index (RI) of arteries in rectal cancerswere detected. Mean color vessels density (MCVD) of rectal cancers were calcuated. Theresults were compared with the postoperative pathological examination.2.43patients with rectal cancer were selected for endorectal elastography andcontrast-enhanced uhrasonography (CEUS). Hardness scoring of rectal tumors wereanalyzed according to improved-5scoring system. Two-dimensional ultrasonography andcolor flow characteristics of rectal lesion were observed by conventional transrectalultrasound.The tumor area were measured separately in the gray scale sonography，elastographic image. Then the area ratio was calculated. The characteristics of contrast enhanced imaging of the rectal cancers were analyzed，including enhancement time，shape，intensity and the hemodynamic changes. The auto-analysis software was used forthe quantity of the tumors and the normal intestinal. Region of interest (ROI) were chosen.The perfusion time-intensity curves and fitting curves were characterized. The time topeak(TTP)，area under the curve (AUC)and other parameters were calculated.ResultsL The total accuracy rate of TRUS in T-staging of rectal cancer was84.5%. Theultrasound T-staging was highly consistent with the pathological T-staging(Kappa=0.767，P=0.000). The diagnostic sensitivity rates in T1?T4stage by TRUS were80.0%,66.7%,85.2%and94.1%. The diagnostic specificity rates in T1?T4stage byTRUS were98.1%、95.9%、90.3%and92.7%.The accuracy rate of TRUS in N-staging ofrectal cancer was69.0%. The ultrasound N-staging was not satisfied enough consistentwith the pathological N-staging (Kappa=0<.352，P0.05). The sensitivity rate of TRUS inN-staging of rectal cancer was60.9%,while the specificity rate of TRUS in N-staging ofrectal cancer was74.3%. The circumference of the intestinal wall of tumor invasion ofadvanced stage rectal cancer group (PT2~PT4) was greater than the circumference of theintestinal wall of tumor invasion of the early stage group(PTl). The difference of thecircumference of the intestinal wall of tumor invasion between the two groups isstatistically significant (P<0.05)The tumor vertical diameter and thickness of early stagerectal cancer group(PTl) were (1土.10.3)cm and (0土.60.2)cm，while the tumor verticaldiameter and thickness of advanced stage rectal cancer group(PT2~PT4) were (2土.90.6)cm and (1.7土0.5)crrL The difference of vertical diameter and thickness between the twogroups was statistically significant (P <0.05).The RI value of early stage rectal cancergroup (PTl) was0.72土0.05，while the RI value of advanced stage rectal cancer group(PT2~PT4)was0.65土0.07. The difference of the RI value between the two groups wasstatistically significant (P<0.05). The difference of the peak systolic velocity (PSV) valuebetween the two groups was not statistically significant (P〉0.05). The MCVD value ofearly stage rectal cancer group (PTl) was0土.160.03，while the MCVD value of advancedstage rectal cancer group (PT2~PT4)was0.25土0.04. The difference of the MCVD value between the two groups was statistically significant (P<0.05). The MCVD value of PNOstage rectal cancer group was0.22土0.03，while the MCVD value of>PN1stage rectalcancer group was0.29土0.03. The difference of the MCVD value between the two groupswas statistically significant (P<0.05).2. The area ratio value of the elastographic images and the gray scale sonographicimages in advanced stage rectal cancer group (PT2~PT4) was1.31土0.15while the arearatio value of the elastographic images and the gray scale sonographic images in earlystage rectal cancer group (PTl)was1.17土0.12.The area ratio value of the elastographicimages and the gray scale sonographic images in advanced stage rectal cancer group(PT2~PT4) was obviously greater than those in early stage rectal cancer group (PTl).Thedifference of the area ratio value between the two groups was statistically significant(P<0.05). The strain ratio value of advanced stage rectal cancer group (PT2~PT4) was10.9土5.1while the strain ratio value of early stage rectal cancer group (PTl)was6.3土4.9.The difference of the strain ratio value between the two groups was statistically significant(P<0.05). The difference of the vascular grading between advanced stage rectal cancergroup and early stage rectal cancer group was statistically significant (P<0.05). Contrastenhanced ultrasound imaging could show blood vessels and microvessels of rectal tumorwhich could not be showed by the conventional color Doppler ultrasound.Contrastenhanced uhrasonography could be helpful to identify the tumor and surrounding normaltissue. Compared with the normal intestinal，the area under curve (AUC)increased whilethe time to peak(TTP) in tumors decreased. The AUC of rectal cancer group (526.3土191.5dB.s) was more than the AUC of rectal wall group (223.2土79.6dB.s)，while the TIP ofrectal cancer group(16.7土4土.6s) was less than the TIP of rectal wall group(28.87.9s).Thedifferences of the AUC and TIP between the two groups was statistically significant(P<0.05). The AUC of advanced stage rectal cancer group (556.5土176.8dB.s) was morethan the AUC of early stage rectal cancer group (371.5土205.8dB.s), while the TIP ofadvanced stage rectal cancer group (16.6土4.3s) was less than the TIP of early stage rectalcancer group (21.2土2.5s).The differences of the AUC and TIP between the two groupswas statistically significant (P<0.05). ConclusionsL The measurement of rectal cancer invasion intestinal circumference, RI value andMCVD value could be helpful to improve the accuracy of preoperative staging. Considedas a preoperative assessment method of the quantitative index of rectal cancerangiogenesis indicators, MCVD is valuable for choice of treatment and evaluation ofclinical prognosis.lt has a promising potential and broad prospect of clinical application.2.Ultrasound elastography may be assistant method to the conventional transrectalultrasound for preoperative staging of rectal cancer.Ultrasound elastography combinedwith scoring system, the area ratio and strain rate ratio is helpful to improve the accuracyof preoperative staging of rectal cancer. Ultrasound elastography is an effectivesupplementary means for preoperative evaluation rectal cancer staging.3.CEUS can directly reflect perfusion status of rectal cancer,also can provide moreinformation for the evaluation of preoperative staging of rectal cancerJt is helpful toimprove the accuracy of preoperative staging, with a great application value and broadapplication prospects.4.TRUS is an effective examination means which can accurately assess the depth ofinvasion of rectal cancer and is a major examination method for preoperative assessmentof the depth of invasion of rectal cancer. It may provide reliable evidence for planningclinical treatment.5.However TRUS preoperative assessment of N-staging result sometimes was notsatisfied enough and combination of MRI，CT and other imaging technology may beneeded for comprehensive evaluation. The problem of application of ultrasonicelastography in a part of rectal cancers was difficult to obtain satisfactory elastic images,which may affect the accuracy of the evaluation of transrectal ultrasound elastography inrectal cancer.