Application of endorectal elastography to evaluate local advanced rectal cancer after neoadjuvant radiochemotherapy: compared with pathology

Objective To evaluate the value of endorectal elastography with strain ratio to estimate local advanced rectal cancer after neoadjuvant radiochemotherapy. Methods In a retrospective study, endorectal ultrasound, endorectal elastography and enhanced rectal MRI were performed in 67 patients with local advanced rectal cancer after neoadjuvant radiochemotherapy. The imaging results were compared with postoperative pathological T stage and NCCN TRG. Results There was no significant difference in the diagnosis accuracy between T stage of ERUS (55.2%) and MRI (56.7%). Endorectal elastography results showed lesions confined to the rectal wall (T0-2 stage) were softer than lesions invaded the peripheral fat (T3) and the difference was statistically significant(P<0.05). When the cut-off point was set at SR<2.78, the sensitivity, specificity and accuracy of diagnosis of T0-2 were 64.7%, 87.5% and 70.1% respectively. The lesion tended to have a greater SR value when residual tumor components increased(a higher NCCN TRG). Conclusions Endorectal elastography is an useful and effective imaging method to evaluate local advanced rectal cancer after neoadjuvant radiochemotherapy. It can help ERUS and rectal MRI to evaluate the lesions. Key words: Endosonography; Elasticity Imaging Techniques; Rectal Neoplasms; Neoadjuvant Radiochemotherapy; NCCN Tumor Regression Grade