A Comparative Study On Diagnostic Value Of MSCT And Mri In Preoperative Local Staging For Rectal Cancer After Neoadjuvant Chemoradiotherapy

Objective: To investigate the diagnostic value of MSCT and MRI in preoperative local staging for advanced lower rectal cancer after standardized Neoadjuvant chemoradiotherapy.Methods: In 145 patients with locally advanced rectal cancer treated with preoperative CRT and surgery,two radiologists measured tumor volume on MSCT and MRI images before and after CRT.CT/MRI-based tumor volumetry and the modified response evaluation criteria in solid tumors(mRECISTs)were compared with T?N and CRM downstaging after CRT,and the tumor regression grade.Results: In MRI group,there were 4 cases of complete remission,23 cases of partial remission,8 cases of stabilization and 3 cases of progress after NACRT.The effective rate was 71.1%.On the MSCT,NACRT achieved complete remission in 16 cases,partial remission in 63 cases,stabilization in 17 cases and development in 11 cases;the effective rate was 73.8%.There was not any statistically significant difference between the two groups(?2 = 0.011,P> 0.05).There was a great agreement between preoperative T stage and CRM invasion(P <0.05).There was a fair agreement between preoperative T stage and postoperative pathological results(Kappa=0.546,0.685)The same as MRI,MSCT does well in CRM and T stage(Kappa = 0.503,0.650).The MSCT preoperative N staging and the postoperative pathologic findings showed a lower consistency(Kappa=0.299).(P> 0.05);(2)N staging: There was no significant difference between the two groups(P> 0.05);(2)There was no significant difference in the accuracy of the two groups(P> 0.05)?2= 0.154,P> 0.05).(3)There was not any statistical difference between the two groups(?2 = 0.344,P> 0.05).Conclusion: NACRT can effectively reduce the tumor size and tumor stage,but no significant improvement in CRM.MRI and MSCT can accurately judge the degree of tumor invasion,but the accuracy of lymph node metastasis is poor,and there is no significant difference between the two groups.Both of the two kind of imaging system can effectively evaluate the effect of neoadjuvant chemoradiotherapy.