Endometrial carcinoma: diffusion-weighted imaging diagnostic accuracy and correlation with Ki-67 expression

AIM: To evaluate the role of diffusion-weighted imaging (DWI) in the detection of endometrial carcinoma and to correlate the apparent diffusion coefficient (ADC) value with Ki-67 expression. MATERIALS AND METHODS: Fifty-two patients with invasive cancer who underwent pelvic MRI were prospectively evaluated using DWI with b-values of 0 and 1000 s/mm2.The ADC values from standard DWI were measured. The expression of Ki-67 in histological specimens was analysed using immunohistochemistry. The ADC values of endometrial carcinoma and normal endometrial parenchyma were compared. Relationships between ADC values and Ki-67 expression were determined using Wilcoxon's signed rank test and the Kruskal-Wallis test. RESULTS: Endometrial carcinoma was detected at DWI as a hyperintense area in 92.3% (48/52) of patients. There was a significant difference in the mean ADC values between endometrial carcinoma and normal endometrial parenchyma (1.39 +/- 0.27x10(-3) versus 0.93 +/- 0.21x10(-3) mm(2)/s, p<0.001). The mean ADC values of grade 1 patients were significantly higher than those of grade 3 patients (1.01 +/- 0.16x10(-3) versus 0.83 +/- 0.21x10(-3) mm(2)/s, p<0.05). The mean ADC values of stage IB patients were significantly lower than those of stage IA patients (0.86 +/- 0.16x10(-3) versus 1.04 +/- 0.21x10(-3) mm(2)/s, p<0.01). The mean ADC values of high Ki-67 expression patients were significantly lower than those of low Ki-67 expression patients (0.82 +/- 0.12x10(-3) versus 1.16 +/- 0.12x10(-3) mm(2)/s, p<0.001). There was a significant negative correlation between the mean ADC value and Ki-67 expression (r=-0.82, p<0.001). CONCLUSION: The ADC value was a helpful parameter for detecting the tumour grade, stage, and proliferation of endometrial carcinoma, and may further improve patient prognosis and contribute to the development of more effective treatment programmes. (C) 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.