Role of diffusion-weighted MRI in the differential diagnosis of endometrioid and non-endometrioid cancer of the uterus.

Background Many publications have examined the relationship between apparent diffusion coefficient (ADC) values and tumor grade in endometrial cancer. Nevertheless, none were designed to evaluate according to the histopathological type of endometrioid and non-endometrioid tumors. Purpose To evaluate the role of diffusion-weighted imaging (DWI) in the differential diagnosis of endometrioid and non-endometrioid cancer of the uterus, by comparing them with contrast-enhanced magnetic resonance imaging (MRI) findings. Material and Methods Institutional review board approval and informed consent were obtained. The MRI findings of 63 patients with endometrial cancer were retrospectively evaluated and divided into four groups: Grades I, II, and III endometrioid tumors, and non-endometrioid tumors. ADC values, DWI quotients ( b = 1000 s/mm), and post-contrast signal intensities between lesions and the myometrium (b1000q-Cq values) were evaluated. The one-way-ANOVA, student's t-test, Kruskal-Wallis test, and receiver operating characteristic (ROC) analysis were used for statistical evaluation. Results Mean ADC values were 0.86 ± 0.14 in Grade I, 0.80 ± 0.7 in Grade II, 0.71 ± 0.14 in Grade III for endometrioid tumors, and 0.70 ± 0.12 in non-endometrioid tumors. There was a significant difference in ADC values between Grade I and Grade III ( P = 0.006), and non-endometrioid tumors ( P = 0.003). The difference was also significant between Grades I + II and Grade III ( P = 0.009), and non-endometrioid tumors ( P = 0.004). Besides, there was a significant difference between endometrioid and non-endometrioid tumors ( P = 0.022). However, when considering b1000q (F = 0.640, P = 0.593) and Cq (χ= 6.233; P = 0.101), no significant difference was detected among the groups. Conclusion The difference in ADC values between the endometrioid and non-endometrioid tumors was statistically significant. However, the difference in DWI and contrast-enhancement findings were not statistically significant. Furthermore, the mean ADC values had an inverse relationship with tumor grade in the endometrioid cancer group.