Abstract: This study explored the correlation and clinical predictive value of the apparent diffusion coefficient (ADC) value of diffusion weighted imaging (DWI) with the type and degree of pathological differentiation of rectal cancer. Using a retrospective study, 105 patients with rectal cancer were selected as observation group, and 50 patients with benign rectal lesions were selected as the control group. Compared the difference of ADC value between the two groups, and then analyzed the differences of ADC values in rectal cancer patients with different clinicopathological and prognosis. The results showed that, the ADC value of lesions in the observation group was significantly lower than that in the control group (P<0.05). The ADC values of patients with low differentiation, Dukes stage C-D, extranodal tumor implantation and Ki-67 ≥ 14% were significantly lower than that of patients with medium and high differentiation, stage A-B, no extranodal tumor implantation and Ki-67<14% (P<0.05). The ADC value of rectal cancer lesions was negatively correlated with Ki-67 (r=-0.578, P<0.05). ADC value predicted the areas under ROC curve of poorly differentiated and Dukes stages C-D were 0.827 and 0.770, respectively (P<0.05). ADC value predicted the area under ROC curve with extranodal tumor implantation was 0.620 (P>0.05). The ADC value of lesions in deceased patients was lower than that of surviving patients (P<0.05). The area under ROC curve of ADC value predicting prognosis was 0.602 (P>0.05). The ADC value of rectal cancer has certain application value in predicting the degree of differentiation and Dukes stage.

Key words: magnetic resonance diffusion weighted imaging, apparent diffusion coefficient, rectal cancer, clinicopathological features, predictive value[HQ]