Application of transrectal elastography and contrast-enhanced ultrasound in evaluation of the efficacy of neoadjuvant therapy for rectal cancer

Abstract

Objective To explore the value of transrectal elastography and contrast-enhanced ultrasound in evaluation of the efficacy of neoadjuvant therapy for rectal cancer. Methods Forty patients with final diagnosis of advanced(T≥3) rectal cancer were respectively examined with transrectal ultrasound (TRUS), endorectal elastography and contrast-enhanced ultrasound(CEUS) before and after neoadjuvant therapy(NET). The tumor size, strain ratio and quantitative parameters of contrast-enhanced ultrasound including arrival time(AT), time-to-peak (TTP), peak intensity(PI) and area under the curve(AUC) were recorded and compared before and after NET.In addition, the TRUS stages and postoperative pathological diagnosis were compared after NET. Results ①There were significant decreases in tumor size and strain ratio after the therapy compared with pre-therapy in all these patients(t=-6.13, P<0.001; t=-24.92, P<0.001). ②PI and AUC were lower after NET than those of pre-therapy 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 significances (t=-1.17, P=0.307; t=-1.26, P=0.275). ③The accuracys of preoperative TRUS for T stage and N stage of tumor evaluated according to pathology were respectively 75.0%(30/40, Kappa=0.593, P=0.000) and 72.5%(29/40, Kappa=0.396, P=0.009). Conclusions Transrectal elastography and contrast-enhanced ultrasound can reflect the pathological changes and perfusion characteristics of lesions in a certain extent and have high value in clinical therapy. Key words: Elasticity imaging techniques; Contrast-enhanced ultrasound; Rectal neoplasms; Neoadjuvant therapy