Abstract:Objective To evaluate the value of apparent diffusion coefficient (ADC), ratio of ADC (rADC) and coefficient variance (CV) of ADC value in differential diagnosis of stage Ia endometrial carcinomas and submucous myomas. Methods Sixty eight patients with stage Ia endometrial carcinoma and submucous myoma underwent MRI plain scan, dynamic contrast-enhanced scan and DWI. The ADC values of lesions and normal uterine myometrium, gluteus maximus and musculi obturator internus were measured respectively, and the corresponding rADC value and CVADC were calculated. The ADC value, rADC value and CVADC value of stage Ia endometrial carcinomas and submucosal myomas were compared. The efficiencies of ADC value and rADC value and CVADC value were assessed by independent sample t test and receiver operating characteristic (ROC) curve. Results The ADC value and rADC value in stage Ia endometrial carcinomas group were significantly lower than those in submucous myoms group (P?0.05), while the CVADC value was higher than that in submucous myomas group (P?0.05). The results of single index ROC curve analysis showed that the area under ADC value curve (0.933) and rADC value curve (0.878, 0.882, 0.913) were significantly larger than that under CVADC value curve (0.665). The results of combined index ROC curve analysis showed that the area under each combined index curve was larger than that under each single index. Conclusions ADC value and rADC value have high diagnostic value in differentiating stage Ia endometrial cancer from submucosal myoma, but the diagnostic efficiency of rADC value is not better than that of ADC value. CVADC value is less effective on differentiating stage Ia endometrial cancer from submucosal myoma. ADC value combined with rADC gluteal muscle value have higher value in identifying these two diseases.